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PB95-192191 Wwwzd= tz azw 4a.:,"Juza. INDICATOR DEVELOPMENT: SEAGRASS MONXTORING AND RESEARCH IN THE GULF OF MEXICO. REPORT OF A WORKSHOP. HELD IN SARASOTA, FLORIDA ON JANUARY 28-29, 1992 .(U.S.) NATIONAL BIOLOGICAL SURVEY, LAFAYETTE, LA DEC 94 .In% SH393 U55 153 1994 U.S. DEPARTMENT OF COMMERCE National Technical information Service TECHNICAL REPORT DATA (PL READ INSTRUCTIONS ON THE REVERSEREFOF 1. REPORT NO 2 3. P EPA620R94029 PE95-192191 4. TITLE AND SUBTITLE 5, REPORT DATE December 1994 indicator Development: Seagrass Monitoring and Resea-ch in the Gulf of Mexico 6. PERFORMING ORGANIZATION CODE 7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO Npckles. H. A. (ad.) 1994. National Biological Survey 9, PERFORMING ORGANIZATION NAME AND ADDRESS 10. PRO(3RAM ELEMENT NO. U.S. Environmental Protection Agency, Office of Research and Development. 11. CONTRACT/GFIANT NO. Environmental Research Laboratory. Gulf Breeze. FL 32561 DW 14936928-01-0 12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED U.S, ENVIRONMENTAL PROTECTION AGENCY ENVIRONMENTAL RESEARCH LABORATORY 14, SPONSORING AGENCY CODE OFFICE OF RESEARCH AND DEVELOPMENT GULF BREEZE. FLORIDA 32561 15. SUPPLEMENTARY NOTES This document is a final report of a workshop co-sponsored by U.S. EPA EMAP-Estuaries. The National Biological Survey and NOAA in 1992. 16. ABSTRACT. Seagrass habitats in the Gulf of Mexico have declined precipitously during the past 50 years. Most habitat losses can be attributed to effects of coastal population growth and accompanying municipal, industrial. and atjncuttural development. Although proximate causes of local declines can sometimes be identified, the majority of habitat loss has resulted from widespread deterioration of water quality. Restoration and preservation of these important habitats depend foremost on improving scientific understanding of the complex causal relationships between anthropogenic stress and seagrass ecosystem persistence. and on developing scientifically based management programs for seagrm conservation. On January 28-29. 92. approximately 60 researchers, State and Federal regulators. and environmental managers met at Mote Marine ,@l . Florida. to address monitoring strategies, research programs and mapping of submerged aquatic vegetation Laboratory in Sar resources in the If of Mexico. This report summarizes the results of the workshops, emphasizing the recommendations of participants in an attempt to guide del elopment of a comprehensive seagrass conservation program in the Gulf of Mexico. IT KEY WORDS AND DOCUMENT ANALYSIS A. DESCRIPTORS B. IDENTIFIEFIS/OPEN ENDED TERMS C. COSATI FIELDIGROUP 16. DISTRISUT!ON STATEMENT 19. SECURITY CLASS (THIS REPORT) 21. NO. OF PAGES UNCLASSIFIED 64 XX 59 RELEASE TO PUBLIC 20- SECURITY CLASS (THIS PAGE) 22. PRICE UNCLASSIFIED EPA Form 2220-1 (Rev. 4EJ Previous Edition is Obsolete PB95-192191 EPA/620/R-94/029 December 1994 Indicator Development: Seagrass Monitoring and Research in the Gulf of Mexico Report of a Workshop Held at Mote Marine Laboratory in Sarasota, FL January 28-29, 1992, Edited by Hilary A. Neckles National Biological Survey Southern Science Center Lafayette, LA Project Officer J. Kevin Summers US. Environmental Protection Agency Property of CSC Library EMAP-Estuaries Environmental Research Laboratory Office of Research and Development US Department of Commerce NOAA Coastal Service Center Library 2234 South Hobson Avenue Charleston, SC 29405-2413 U.S. Environmental Protection Agency Gulf Breeze, FL 32567 Printed on Recycled Paper DISCLAIMER This document has been reviewed in accordance with U.S. EnvironmenLil Protection Agency policy and approved for publication. Mention oftra(le names or cominercial prodUCLs dix@s not constitute endorsement or recommendation for uw. OF Seagrass Monitoring and Research - 1992 Page iii PREFACE This document is a final report of a workshop co-sponsored by U.S. EPA, EMAP-Estuaries. The National Biological Survey and NOAA in 1992. The appropriate citation for this report is: Neckles, H.A.(ed.) 1994. Indicator Development: Seagrass Monitoring and Research in the Gulf of Mexico. U.S. Environmental Protection Agency. Office of Research and Development, Environmental Research Laboratory, Gulf Breeze, FL. EPA/620/R-94/029. Seagrass Monitoring and Research-1992 Page iv ACKNOWLEDGMENTS This workshop was sponsored by the U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Service, and the National Oceanic and Atmospheric Administration. We thank the scientists and resource managers who participated in the workshop and whose ideas and discussions form the basis of this report. We are especially grateful to Mike Durako, Ken Haddad, and Chris Onuf for leading working groups on research, mapping, and monitoring: to Ernie Estevez, Mark Fonseca, Ken Moore, and Judy Stout for leading working groups on conservation objectives to Julie Morris for assisting with workshop organization and for facilitating all discussions: and to Bill Dennison for chairing the plenary sessions and finding the common threads among working group reports. Kumar Mahadevan and the staff of Mote Marine Laboratory graciously hosted the workshop and provided on-site support critical to workshop success, and Martha Griffis, Lois Haseltine, and Cam Wiik assisted in preparation of this report. Workshop Steering Committee: Hilary A. Neckles, National Biological Survey W. Judson Kenworth, National Marine Fisheries Service William L. Kruczynski, U.S. Environmental Protection Agency J. Kevin Summers, U.S. Environmental Agency Seagrass Monitoring and Research-1992 Page v WORKSHOP PARTICIPANTS Susan S. Bell, Ph.D.,University of South Florida, Tampa, Fl. Douglas A. Bulthuis, Ph.D.,Padilla Bay National Estuarine Research Reserve, Mt. Vernon, WA Otto S. Bundy, Horticulture Systems, Inc.,Parrish, FL JoAnn M. Burkholder, Ph.D.,North Carolina State University, Raleigh, NC Paul R. Carlson, Jr.,Ph.D.,Florida Department of Natural Resources, St. Petersburg, FL James K. Culter, Mote Marine Laboratory, Sarasota, FL Clinton J. Daws, Ph.D.,University of South Florida, Tampa,FL Robert Day, Indian River Lagoon National Estuary Program, Melbourne, FL William C. Dennison, Ph.D.,University of Queensland, St. Lucia, Qld.,Australia L. Kellie Dixon, Mote Marine Laboratory, Sarasota,Fl. Kenneth W. Dunton, Ph.D.,University of Texas at Austin, Marine Science Institute, Port Arkansas, TX Michael J. Durako, Ph.D.,Florida Department of Natural Resources, St. Petersburg,FL Lionel N. Eleuterius, Ph.D.,Gulf Coast Research Laboratory, Ocean Springs, MS Ernest D. Estevez, Ph.D.,Mote Marine Laboratory, Sarasota, FL Randolph L. Ferguson, Ph.D.,National Marine Fisheries Service Laboratory, Beaufort, NC David A. Flemer, Ph.D.,U.S. Environmental Protection Agency-Environmental Research Laboratory,Sabine Island, Gulf Breeze, FL Ruth Folit, New College Environmental Studies, Sarasota,FL Mark S. Fonseca, National Marine Fisheries Service Laboratory, Beaufort,NC Charles I. Gallegos, Ph.D.,Smithsoniar, Environmental Research Center, Edgewater, MD Holly S. Greening, Tampa Bay National Estuary Program, St. Petersburg, FL Ken D. Haddad, Florida Department of Natural Resources, St. Petersburg,Fl Margaret O. Hall, Ph.D.,Florida Department of Natural Resources, St. Petersburg, FL Lawrence R. Handley, National Biological Survey, Southern Science Center, Lafayette, LA M. Dennis Hanisak, Ph.D.,Harbor Branch Oceanographic Institute, Ft. Pierce, FL Kenneth I. Heck.,Jr.,Ph.D.,Dauphin Island Sea Laboratory, Dauphin Island,AL Jeff G. Holmquist, Ph.D.,University of Puerto Rico, Lajas PR Roger Johansson, City of Tampa, Tampa,FL James B. Johnson, Ph.D.,National Biological Survey, Southern Science Center, Lafayette, LA W. Judson Kenworthy, Ph.D., National Marine Fisheries Service Laboratory, Beaufort,NC William L. Kruczynski, Ph.D.,U.S. Environmental Protection Agency-Environmental Research Laboratory, Sabine Island, Gulf Breeze, FL Brian E. Lapointe, Ph.D.,Harbor Branch Oceanographic Institute, Big Pine Key, FL Lynn W. Lefebvre, Ph.D.,U.S. Fish and Wildlife Service, Gainesville, FL Jay Leverone, Mote Marine Laboratory, Sarasota, FL Helene Marsh, Ph.D.,James Cook University, Townville,Qld.,Australia Mike J. Marshall, Ph.D.,Mote Marine Laboratory, Sarasota, FL Peggy H. Mathews, Department of Environmental Regulation, Tallahassee,FL John M. Macauley, U.S. Environmental Protection Agency-Environmental Research Laboratory. Sabine Island, Gulf Breeze, FL Benjamime F. McPherson, Ph.D.,U.S. Geological Survey, Tampa,FL Seagrass Monitoring and Research-1992 Page vi Kenneth A. Moore. College of William and Mary. Virginia Institute (if N4arine Science. Gloucester Point, VA Julie Morris. New College Fnvironmental Studies. Sarasota. 11. Hilary A. Neckles, Ph.D.. National Biological Survey, Southern Science Center. Lafayette. LA Walter Nelson. Ph.D.. Florida Institute of Technology, Melhoume. 11. John C. Ogden. Ph.D.. Florida Institute of Oceanography, St. Petersburg. 11. Christopher P. Onuf, Ph.D.. National Biological Survey. Corpus Christi. TX Robert J. Orth, Ph.D., College of William and Mary, Virginia Institute of Marine Science. Gloucester Point, VA Ronald C. Phillips. Ph.D.. Battelle, Pacific Northwest Laboratories, Richland. WA Warren M. Pulich. Jr.. Ph.D., Texas Department of Parks and Wildlife. Austin.TX Thomas F. Ries. Southwest Florida Water Management District. Tampa. 1-1. Frederick T. Shon. Ph.D.. Univeisity of New Hampshire. Jackson Estuarine Laboratory. Durham. NH Kenneth N. Smith, Florida Department of Natural Resources, Tallahassee, 17L OF Judy P. Stout. Ph.D.. Dauphin Island Sea Laboratory. Dauphin Island. Al- Michael J. Sullivan, Ph.D.. Mississippi State University. Mississippi Stale. MS - J. Kevin Summers, Ph.D.. U.S. Environmental Protection Agency-Environmental Research LaNiratory. Sabine Island. Gulf Breeze. F-L John Thompson. Continental Shelf Associates, Jupiter. T-T. David A. Tomasko. Ph.D., Sarasota Bay National Estuary Program. Sarasota. FL Dean A. Ullock, U.S. Environmental Protection Agency. Coastal Programs Section, Atlanta. GA Robert W. Virnsein. Ph.D., St. Johns River Water Management District. Palatka. F1, Pichard L. Wetzel, Ph.D., College of William and Mary. Virginia Institute of Marine Science. Gloucester Point. VA Susan L. Williams, Ph.D., San Diego State University, San Diego, CA Joseph C. Zieman. Ph.D., University of Virgipia. Charlottesville. VA Richard C. Zimmerman, Ph.D.. University of California. Los Angeles. CA Seagrass Monitoring and Research - 1992 Page vii TABLE OF CONTENTS DISCLAIMER ........................................... I ................................ iii PREFACE ......................... ................................................. iv ACKNOWLEDGMENTS ....................................................................... . WORKSHOP PARTICIPANTS ......... V, INTRODUCTION ........................................................................... 9 RECOMMENDATIONS ........................................................................ 11 BACKGROUND FOR RECOMMENDATIONS: WORKSHOP PRESENTATIONS AND DELIBEICATIONS ........................................................................... 15 CONSERVATION AND RESTORATION OFTHE SEAGRASSES OFTHE GLI-F OFMEXICO THROUGH A BETTER UNDERSTANDING OF THEIR MINIMUM LIGHT REQUIR1.MENTS AND FACTORS CONTROLLING WATER TRANSPARENCY 17 W. Judson Kenworshy SUBMERGED AQUATIC VEGETATION MAPPING ............................................... 33 Lawrence R. Handley ECOLOGICAL INDICATORS ......................................................... ........ 43 Hilary A. Neckles SUBMERGED AQUATIC VEGETATION RESEARCH NEEDS ................ ............... St. %iffiam I- Krucqnski SEAGIUSS CONSERVATION IN THE GULF OF MEXICO: AN ACTION AGENDA .............. 59 'Hilary A. Neckles @ I . I - . I I. APPENDIX A .............................................. ............................ 63 Seagrass Monitoring and Research - 1992 Page viii INTRODUCTION Scagrass habitats in the Gulf ol'Mexico have IMAP-Estuaries is designed to characterize th,.: declined precipitously during ihe past 50 years. ecological conditior (if the nation's estuarine and Most habitat losses can he attributed to c flects of coastal resources over broad geographic regions coastal population growth and accompanying and long linic [wriods. The program is intended municipal. industrial. and agricultural to provide quantitative information on the extent development. Although proximate causes of and potential causes ofadverse environmental local declines can sometimes he idenlified. t'ie changes. In an effort to provide one indicator (if maJority of habitat loss has resulted from nearsh(ire environnicnial quality, I:NIAI'- widespread deleriorafion of water quality. Fstuaries is mapping the location and extent of Restoration and preservation (if these important SAV in Lhe coastal region of the Gulf (if Mexico. habitats depend foremost on improving scientific All maps are scheduled to he completed in 1995. understanding of the complex causal Baseline information on !be distribution and relationships between an1hropogenic stress and abundance of SAV will ,then he used to devc1op a seagrass ecosystem persistence, and on monitonng program to assess the status and developing scientifically based management trends of these hahitats. This assessment will he programs for seagrass conservation. based on measurement of defined parameters that serve as indicators of SAV hahitai quality. On January 28-29'. 1992, approximately 60 The workshop developed recommendations for researchers. State and Federal regulators, and SAV mapping. classification. and monitoring in environmental managers met at Mote Marine the Gulf of Mexico. and identified a set of Laboratory in Sarasota. Flotida, to discuss ecological indicators for accurate assessment of strategies for monitoring the environmental SAV habitat condition. status of seagrass hahitats and to determine the research needed it) increase our knowledge of The FTA Wetlands Research Program included wagrass responses to anthropogenic stress. The funding in 1992 for the initiation (if coastal workshop was sponsored by the U.S. wetlands research. The EPA Science Advisory F.rivironmental protection Agency 0:11A). the Board recommended that initial research he U.S. Fish and Wildlife Service. and the National conducted on the effects (if cumulative impacts Oceanic and Atmospheric Administration. The within watersheds on coastal SAV communities. goals of the workshop were to provide technical The workshop identified and prioritized research guidance (in monitoring requirements to the needs to develop a pilot project and a future F.PA F.PA's Environmental Monitoring and Coastal Wetlands Research Initiative on a Assessment Program- F.stuaries and it) assist in national %Late. As a result of this workshop a the development of a coastal wetlands research study of seagrass responses to long-temi light program at the EPA's Environmental Research limitation was initiated at three field sites in the Laboratory-Gulf Breeze. In addition. the Gulf of Mexico. workshop provided a forum for coordinating research and monitoring activities among Following introductory presentations (in FMAP. government agencies. universifies. and private the Wetlands Research Program, and the state of organizations with interest and mandates in the current knowledge of seagra-s-s environmental protection (if submerged aquatic vegetation requirements. workshop participants divided into (SAV) resources in the Gulf of Mexico. three working groups to address Lhe workshop Seagrass Monitoring and Research - 1992 Page 9- objectives: seagrass mapping, ecological indicators. and research needs. At the@end of the workshop, participants reorganized into four working groups. each charged with developing a list of the highest priority actions Ifor preservation and restoration of seagrass systems. The working groups reconvened periodically in plenary sessions to report conclusions. solicit input from other workshop participarts, and to integrate and synthesize recommendations. This report summarizes results of the workshop. emphasizing the recommendations of ,participants in an attempt to guide development ,)f a comprehensive seagrass conservation program in the Gulf of Mexico.' Seagrass Monitoring and Research - I M Page 10 RECOMMENDATIONS Knowledge of seagrass systems and our ability within geomorphic sirata a second tier of to preserve and restore these important habitats sampling stratillication should be introduced. will he advanced most effectively through the based (in bed size, water depth. and sufficial integration of mapping, monitoring. and research sediment type. across a range of spatial and temporal scales (Fig. 1). Specific recommendations within each Mapping of the Louisianan Province should twe of these components., of a comprehensive repeated every four years to assist other SAV seagrass conservation program are listed below. monitoring. to ensure the repeatability of sample locations, and to establish long-term trends in SAV disLributi(,.n and abundaice. MAPPING ECOLOGICAL INDICATORS All maps should be produced at a scale of 1:24,000 to conform to the standard of U.S. Various parameters reflecting SAV responses to Geological Survey topographic quadrangles. environmental stressors can he mc-Mured to quantify the ecological condition (if the habitat. Maps should be developed from aerial Response indicators fall into three classes. photographs combined with extensive concurrent according to their readiness for incorporation field ground-truthing. A minimum list of ground into a long-term monitoring program: data to verify photointerpretafion includes submerged aquatic vegetation (SAV) species 0 Parameters that are ready for implementation present, confirmation of the signature macrop6yte depth lim't, shoot density. identification, nonvegetated features, and aboveground and belowground biomass. location. Other data that can be collected during species composition of SAV and macroalgae. ground truthing yet are not critical to map verification may either assist in 0 Parameters for which field evaluations are photointcrpretation or make the map more necessary to define temporal and spatial useful. These data include SAV density, water variability and to furtkr characterize depth, presence or abundance of epiphytes and relationships to multiple environmental macroalgae, evidence of prop scars, sediment stressors - algal biomass. leaf -width. plant type, turbidity, and salinity. constituents, stress proteins, grazer densities; Global Positioning System technology should be 0 Parameters dependent on newly available technologies that with. significant additional used whenever possible during routine collection of SAV field data to provide true locations for developmem. might be important future correlation with historical, present. and future ecological response indicators - leaf area maps. index measured with an aulomatic meter and genetic diversity using DNA fingerprinting. SAV beds should be stratified for Environmental Monitoring and Assessment Program (EMAP) sampling based on gcomorphic type: hypersaline lagoons, estuaries, open coastal, and deltaic formations. To ensure equal representation 'S..@-agrass Monitorini and Research - 1992 Page 11 Centimeters 40 SPACE No. Kilom .e Days oN TIME Do- D e c a d e Molecule.s v4 COMPLEXITY -o-Ecosyst A(- 3 None of the proposed response indicators have been tested at the regional and decadal scales used by EMAP. Seagrass beds are dynamic, comples systems, and many of the parameters used to characterize habitat condition, therefore, exhibit considerable, temporal and spatial variability. We recommend strongly that the EMAP network be supplemented with increased sample density at selected sites. The ability to detect change from widely spaced samples taken annually must be validated before meaningful statistical confidence can be placed in the use of the proposed indicators to assess regional longterm trends in seagrass ecosystem health. The most important parameters to measure as indicators of the extent of pollutant exposure or habitat degradation present in Gulf of Mexico seagrass systems are water column light attenuation, turbidity, chlorophyll concentrations, dissolved nutrient concentrations, and diet fluctuation in dissolved oxygen concentrations. All of these exposure indicator sexhibit extremee temporal variability, so that single, annual samples would yield no useful information. To provide the needed data, exposure indicators must be evaluated either from frequent sampling or from continuous monitoring at permanent stations. Although the proposed indicators exhibit general relationships with habitat quality, threshold values separating desirable conditions from undesirable ones cannot be indentifgied for any of the variables. Research is needed to better define and validate criteria for interpreting specific values of candidate response and exposure indicators in terms of ecosystem health. RESEARCH NEEDS Research is needed to determine the species specific minimum light requirements for long term persistence and restoration of subtropical seagrasses. Assessment of the responses of seagrass communities to environmental stresses (e.g.. light quantity and quality, nutrients, sediment loading, salinity, temperature) is needed to betterh project the effects of environmental management strategies. This area of research should examine potential changes in seagrass species, productivity, genetic diversity, and reproductive success in response to these parameters. The roles of macroalgae and epiphytes in these changes and the potential complicating effects of plant-animal interactions should be evaluated. Available mapls should be used as a research tool rather than simply as an assessment method. Information on seagrwsss distribution and abundance should be used in correlative and other analyses to generate specific hypotheses on interrelationships among seagrass condition, depth, and other key forcing variables. Very little is known about the environmental requirements of deepwater Halophila spp, communities. This seagrass community requires significant general research to understand its role and importance in marine ecosystems. CONSERVATION OBJECTIVES No permitted losses of existing seagrass communities should be tolerated. This is particularly important in the case of Thalassia beds, for which few examples of successful replacement have been documented. Restoration of seagrasses to historical levels in the Gulf of Mexico will require widespread water quality improvements. This required foremost that anthropogenic nutrient and sediment loading be reduced. Legislative initiatives to protect and restore Gulf of Mexico seagrass communities depend ultimately on strong public support. Public education programs should be developed to increase awareness of, and appreciation for, the Seagrass Monitoring and Research-1992 Page 13 L ecological and econon-tic values of scagrass habitats. A seagrass working group including research. scientists, Federal. State. and local resource managers. and representatives of user groups should he formed to coordinate seagrass conservation efforts in Lhe Gulf of Mexico. Seagrass Monitoring and Research - 1992 Page 14 BACKGROUND FOR RECOMMENDATIONS: Workshop Presentations and Deliberatiou SejWrass MonilorLng and Research - 19L2 Pare 15 CONSERVATION AND RESTORATION Of THE SEAGRASSES OF THE GULF OF MEXICO THROUGH A BETTER UNDERSTANDING OF THEIR MINIMUM LIGHT REQUIREMENTS AND FACTORS CONTROLLING WATER TRANSPARENCY by W. Judson Kenworthy Beaufort Laboratory National Oceanic and Atmospheric Administration National Marine Fisheries Service Southeast Fisheries Science Center Beaufort, NC 28516 Seaems Monitoring and Research - 1992 Page 17 INTRODUCTION .Spanning nearly 5 degrees of latitude and 15 Halophila engelmanni (Fig. 2). Almost always degrees of longitude, the Gulf of Mexico is the found growing completely submerged. ninth largest tiody ol'water in the world. The seagrasses stabilize unconsolidated sediments shallow coastal waters of the gulf consist of an and recycle nutrients while providing food, assortment of physicochemical environment% shelter, and substrate for hundreds of species of including extensive harrier island lagoons, 33 flora and fauna (Durako et al. 1987. Zieman and major river systems. and 207 estuaries. These Zierrian 1999). Despite the low diversity of range from the clear subtropical carbonate species, seagrasses occupy a wide variety of sediment-based systems of the Florida Keys to habitats including, but not restricted to. sand the temperate hypcrsaline Laguna Madre -.n shoals. shallow muddy and sheltered lagoons. Texas, The physical and chemical diversity high-energy tidal channels, and relatively deep provided by these environments supports open-water continental shelves (Continental extensive and highly productive plant Shelf Associates Inc. and Martel Laboratories communities that are valuahlebabitats for Inc., 1985. Iverson and Bittaker 1986. Durako et resident and migratory species of fish and, al. 1987. Zieman et al. 1989, Zieman and Zieman wildlife. The Gulf of Mexico has the largest and 1989). Their ability to grow in these very most valuable shrimp fishery in the United States different environments results from their as well as numerous other important commercial phenotypic plasticity and the wide diversity of and recreational fisheries. many of which depend morphology and life history strategies provided on the shallow vegetated ecosystems fringing the by a remarkably few species. Size alone gulf. illustrates the heterogeneity fumished by the limited species pool. Fully mature seagrass The Gulf of Mexico is experiencing the second communities in the Gulf of Mexico span two fastesi rate of growth of the five coastal regions orders of magnitude in canopy height and of the Uni'@d States. Most growth and belowground structure and three orders of development are occuffirig within a few miles of magnitude in weight. from the small low-relief the shoreline or along the watersheds draining meadows of Halophila decoiens and Halophila into the gulf. Two-thirds of the land area of the engelmanni up to the robust and dense beds of T contiguous United States eventually drains into testudinum (Zieman and Wetzel 1980). In the Gulf of Mexico. delivering organic matter, between these extremes are two conspicuous inorganic nutrients. and fresh water. Unless plants. Halodule wrightii and S. fififorme, which growth and water quality are properly managed, are intermediate in size and reproduce the consequences are a predictable vegetatively at a moderately high rate (Eleuterius environmental degradation and a serious threat 1987, Fonseca et al. 1987). to the health and well-being of the coastal living marine resources. Our understanding of the role seagrasses have in supporting the living marine resources Seagrasses are an important component of the of the Gulf of Mexico. and our ability to predict coastal plant communities in the Gulf of Mexico what the effects of altered water quality will have (Durako et al. 1987. Zieman and Zieman 1989). on these functions, depend on a comprehensive Four genera, including rive of the six tropical understanding of the mechanisms controlling western hemisphere species. grow in the gulf their distribution and abundance. Li ht, , V-1 Thalassia testu&num. Syringodiumfififorme. sqbsLrate, nutrients, and water Halodule wrighdi, Halophila decipiens. and motion constitute _Lhe - m_a__ jor e-n-v-irorunental Sea,arass Monitoring and Research - 1992 Page 18 A- A., Halophila decipie'ns ,H,Vwsd,- wrighdi llalophiw engeL.Mm ,pi UsAmfinson F%ore 2. Mustration of Uw Bve specks of sub-frop" and troocal sengrams towW growbig In tbe Gulf of Mexico (hvm Fonseca, 1"3@ Horlzontml ban I an scalt. Seajerms Monitoring and Researrh - 1992 Page 19 factors controlling seagrass growth. Of these five parameters, light is the most important. The quality and quantity of available photosynthetically active radiation (PAR: 400-700 nm) drive the photosynthetic processes to fix darbon and produce oxygen, two metabolic processes critical for the survival and growth of seagrasses. Ultimately, the amount of light reaching seagrasses depends on water transparency, which is a function of the water quality parameters that influence light alltenuation in the water column and on the surfaces of the leaves (Neckles 1991, Morris and Tomasko 1993). In general, it is difficult to assign overall dominance or abundance to any one of the five species in the Gulf of Mexico. A real distribution is patchy and, depending on the location, relative abundance of species will shift within a few meters. In spite of this variability, consistent patterns of depth distribution provide evidence for the interrelationships between seagrasses and water quality, particularly water transparency (Iverson and Bittaker 1986, Dennison 1987, Durako et al. 1987. Zieman and Zieman 1989, Duarte 1991, Kenworthy and Haunert 1991, Morris and Tomasko 1993). The observed patterns suggest tha tthe five species can be collapsed into three groups with different minimum light requirements...In descending order from highest to lowest-light-requirements they are 1) T. testudinum, 2) Halodule wrightii/S. filiforme, and 3) Halophila decipiens/Halophila englemanni. SEAGRASS MINIMUM LIGHT REQUIREMENTS Two by products of photosynthesis, carbohydrates and oxygen, form the basis of two working hypotheses seeking to explain the mechanisms controlling the distribution of seagrasses (Dennison and Alberte 1986, Marsh et al. 1986, Dennison 1987, Smith et al. 1988. Zimmerman et al. 1989. Zimmerman et al. 1991. Morris and Tomasko 1993). Carbon fixed in photosynthesis i sused to build nonstructural carbohydrates, which support maintenance respiration, and structural carbohydrates, which support new growth (carbon balance: Zimmerman et al. 1989). Oxygen produced in photosynthesis is critical to the metabolic needs of the roots and rhizomes of seagrasses, which often grow in chronically anoxic sediments and are exposed to the potentially toxic effects of reduced sulfur compounds (Penhale and Wetzel 1983, Smith et al. 1984, Smith et al, 1988). Carbon balance and oxygen production are not necessarily competing hypotheses, yet they may operate to different degrees in affecting seagrass distribution, depending on the available species pool and the prevailing submarine light regime. Recent studies have indicated that the minimum light requirements of seagrasses growing in the Gulf of Mexico are much higher than originally suggested by physiological studies of leaf photosynthesis alone (Vincente and Rivera 1982, Onuf 1991, Furquerean 1991, Fourquerear and Zieman 1991, Kenworthy and Haunert 1991, Kenworthy 1992, Morris and tomasko 1993). The traditional definition of the light compensation point (I0, which historically has been 1-5% of the surface incident light, may be appropirate for phytoplanktom, marcroalgae, and charophytes, but it underestimates the requirements of many seagrasses, including those residing in the Gulf of Mexico (Dennison 1987, 1991, Duarte 1991, Kenworthy and Haunert, 1991). Whole plant minimum light requirements, rather than the requirement of leaves alone, define an ecological light compensation point (sensu Goldsborough and Kemp 1988) estimated to be approximately 15-20% of the average annual surface incident light for Halodule wrightii and S. filiforme (Onuf 1991, Kenworthy et al. 1991, Morris and Tomasko 1993). Because of the extensive belowground storage mass of T. testudinum (Dawes 1987, Fourquerean and Seagrass Monitoring and Research-1992 Page 20 heman 199 1), this species may be capable of 199 1. Kenworthy 1992). Thereforc. Halodule withstanding periods of reduced light (Hall et al.. wrightii can sustain growth al lower light levels 199 1). During periods of low light. carbohydrate for longer periods (if time than can T testudinurn reserves may be diverted from the rhizomes to and will survive in deeper water as well as water support whole plant carbon balance (Tomaiko with lower overall transparency fa lower and Dawes 1989). The ability to utilize . reserves minimum light requirement). may depend on the previous light history of the plant. During periods of light stress, carbon This comparison. and the emerging general reserves may become depletcd more rapidly in understanding of the minimum light species like Halodule wrighiii and S. filiforme requirements of seagrasses. suggest that we may that have less belowground storage capability be able to predict what species should be than does T testu&num. Thalassia testudinum growing under different conditions of water may be better adapted to avoid short-term transparency as well as the maximum depth and deficiencies in carbon balance, however, overall areal coverage we should expect in a observations of depth distribution suggest that particular water body. This predictive capability its long-term ligti@ requirements are as high or would be a powerful tool for resource managers perhaps even higher than those of Halodule to use in water management programs designed wrightii and S. filiforime (Vincente and Rivera for the protection and restoration of seagrasses 1982. Phillips and Lewis 1983, Iverson and (Kenworthy and Hauncrt 1991, Zimmerman et al. Bittaker 1986, Kenworthy and Haunen 1991). 199 1, Morris and Tomasko 1993). The adequacy Reported patterns of depth distribution almost of this prediction will depend (in the assumptions always indicate that Halodule wrighrii and S. that an average annual attenuation coefficient or fififoryne grow deeper than T testudinum, some other relevant variable is a reliable reinforcing the hypothesis that factors other than predictor of seagrass condition and that the carbon balance alone are important in factors responsible for light attenuation can he determining light requirements and depth isolated for management attention. Currently. distribution (Zimmerman et al. 195@t). these are two areas of active research interest and should draw the attention of scientists and The larger reservoir of belowground tissues in T managers during development of the US, testudinum meadows may be vulnerable to the Environmental Protection Agency's Coastal phytotoxic effects of reduced sulfur compounds Submerged Aquatic Vegetation Initiative (see, al the lower light levels in relativelydeeper for example, Morris, and Toniasko 1993). water, or during temporary and seasonal periods of poor water transparency. The primary mechanism controlling T. testudinum light requirements may be phytotoxicity rather than carbon balance. whereas Halodule wrighiii is better adapted to minimize both problems. Halodule wrightii can avoid phytotoxicity and maximize carbon balance by having greater oxygen production at low light levels (high alpha). a higher maximum photosynthetic rate (high P., Williams and McRoy 1982. Fourqurean 199 1. Kenworthy 1992), a shallower rooting depth, and lower root-rhizome to shoot ratios (Fourqurean and Zieman 199 1. Fourqurean Seajerass Monitoring and Research - 1992 Paze 21 HOBE SOUND MONTHLY Kd VALUES 0. no - -0.25- -0.50 z < -0.75. LLJ -1.00 -i.25 -1.50 JAN FES MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTH FlgureX Seasonsi eyde ofdWbw PAR 1k*1 atteasadon (K* PAR) In a shadow dM bgooa, H&e Soa"4 he the Softhtm Indian transparencies that are detectable along spatial UNDERSTANDING AND and temporal gradients and directly controlled by PREDICTING SEAGRASS three commonly monitored water quality variables: 1) total suspended solids MS. DISTRIBUTION frequently measured as turbidity by nephelometric turbidity units), 2) chlorophyll (CHL), and 3,1 dissolved organic matter (DOM. Because of the wide diversity of watersheds and usually measured as color. Kirk 1988. Gallegos coastal geomorphology in the Gulf of Mexico. et al. 1990. Gal le gos et al. 199 1. Moore 199 1. there are a variety of nearshore ecosystems and Kenworthy and Haunert 199 1, Morris and water qualities. The result is a range of water Tomasko 1993). Also important are the indirect S@affass Monitoring and Research - 1992 Pa" 22 controls on water transparency operating thro ugh paradigm frequently assigned to 'his pecie., for CHL and DOM. These are dissolved inorganic several reasons. The small, low-density. low- nutrients. mainly inorganic nitrogen and relief canopy minimizes self-shading and allows phosphorous, which stimulate phytoplankton more light to enter. while a shallow rooting and macroalgal blooms as well as the growth of depth avoids the pi)tenfially phytotoxic effects in epiphytes on the leaves of seagrasses. Both the the deeper, more reduced sed i men ts. direct and indirect controls of light attenuation Additionally. Halophila dtcipiens has a have very strong seasonal signatures (Moore simplified anatomy including thin cell walls and 199 1. Kenworthy et al. 199 1. Neckles 199 1. densely packed chl,)roplasts. which maximize Kenworthy 1992. Morris and Tomasko 1993) the amount of light reaching the chlorophyll which suggest that mechanisms controlling molecules (Josselyn ct al. 1986). The individual short-term light limitation may be masked by leaves grow rapidly and turnover is fast enough estimating the minimum light requirements of to minimize the establishment of epiphytes that seagrasses through a simple correlation between could further attenuate light on the surfaces of an average annual light attenuatior coefficient the leaves (Josselyn et al. 1986, Kenworthy et al. and the maximum depth of growth (Dennison 1989). Based on these physiological and 1987, Duarte 1991, Kenworthy and Haunert morphological attributes, Halophila decipiens 199 1. Zimmerman et al. 199 1). should have a lower minimum light requirement than the larger species (Josselyn et al. 1986). yet The problem with inferring light limitation by a they grow only in summer during maximum correlation between maxinturn depth of growth photoperiod and intensity. and ft average annual attenuation coefficient was illustrated by an intensive study of the There is another plausible explanation for the submarine light regime and seagrass distribution observed seagrass depth distribution that is in the southern Indian River (Kenworthy et al. based on the life history of these species rather 199 1, Kenworthy 1992). Weekly sampling of than just their physiological anI anatomical the light attenuation coefficients in two coastal characteristics. Althoughsexual reproduction lagoons showed significant effects related to occurs with all the species growing in the Gulf of time and distance from an inlet. During four Mexico (McMillan 1985, Moffler and Durako years of sampling, a repeatable cycle of summer 11987). Halophila decipiens is by far the most maximum and winter minimum transparencies fecund. In the southern Indian River was detected (Fig. 3). Based on the average (Kenworthy 1992). and even in the tropical annual light attenuation coefficient, Halodute environment of the Salt River Canyon in St. wrightii and S. filiforme grew to a maximum Croix (Josselyn et al. 1986. Williams 1988. depth corresponding to light levels of 15 and Kenworthy et al. 1989). ephemeral populations 37% of the incident light. Even though light of Halophila decipiens are reestablished levels exceeded this average value in deeper annually by seed. During the winter periods of water during the summer months (May-August). low light and low temperatures in the Indian these two species could not establish permanent River, populations of Halophila decipiens populations there. Yet. healthy populations of a disappear except in the immediate vicinity of smaller species, Halophila decipiens. grew in the inlets, where relatively warmer and clearer water deeper water between May and October prevails throughout the winter. In other (Kenworthy 1992). If observations on seagrass subtropical and tropical locations fall and -winter distribution were obtained only during the clear storms contribute to the erosion and burial of suriuner period the depth transects would have existing Halophila decipiens beds. leading to a suggested that Halophila decipiens was the seasonal decline in abundance and cover; this species adapted to the lowest light levels, a occurs even in tropical deepwater beds of the SeagMs Monitoring and Research - 1992 Paw 23 Virgin Islands (Williams 1988). In the Big Bend physiology. anatomy, or temporally static depth region of the eastern Gulf of Mexico there are transecLs alone. Seagrass light requirements vast areas of deep water (depth > 10 m) on the depend in part or. the life history patterns of the continental shelf that are vegetated by Halophila individual species, reinforcing the argument Lhat decipiens and Halophila engelnianni . an average annual attenuation coefficient may (Continental Shelf Associates Inc. and Martel not adequately predict the distribution of some Laboratories Inc. 1985, Confintal Shelf seagrasses (Zimmerman et al. 1991). The Associates Inc. 1989). Although there are no survival. growth. and year-to-year persistence (if detailed seasonal studies of these deepwater Halophila deripiens in die lidian River beds. an evaluation of Hurricane Elena's impact ce i.,imunities may depend largely on the water in 1985 revealed that Halophila meadows were quality in summer, when actively growing completely destroyed, yet they recovered during population 's are forming seed stocks that will be the following growing season (Continental Shelf the basis for the next year's population. If Aisociates Inc. 1987). This indicates that these growth and fruiting slow or cease during cooler populations are based on an annual life history months (October-Aprfl). the light attenuation strategy. values obtained in winw will have no bearing at all on predicting the success of populations in The storm-impacted beds in the Gulf of Mexico subsequent years. and St. Croix, and the seasonally ephemeral Halophila decipiens beds of the southern Indian This same argument probably applies to the three River, are reestablished by seed. In the Indian larger species as well, but for different reasons. River seedlings emerge in early spring (March- During the active growing periods of spring. May) and continue to germinate throughout the summer. and early fall. good water transparency summer, forming patchily disuibuted meadows may ensure an adequate production of ' in deeper water but never in the canopy of the belowground storage carbohydrates that can be larger specieg that grow in relatively shallower mobiliLed to short shoots during periods of algal water. Seed germination, seedling growth. and overgrowth or low light in winter, or for bed development coincide with ihe highest levels regrowth the following spring (Dawes 1987, of PAR observed during the year (Kenworthy Tomasko and Dawes 1989). Equally or perhaps 1992). Because Halodule wrightii. S. filifomie. more important. for the larger species that and T. testudinum reproduce mainly by produce considerable belowground biomass. is vegetative branching (Tomlinson 1974). they the immediate production of oxygen and carbon have limited dispersal potential. These larger skeletons. These end products of photosynthesis species cannot utilize the available light in detoxify reduced sulfur compounds and nitrogen deeper water because the time window is too (nitrate), whereas the production of alternate end short.for vegetative propagation and dispersal to products (carbon compounds) minimizes the take advantage of the resource. Volunteer phytotoxic effects of ethanol during nighttime fragments, consisting of a few short shoots. and during daytime periods of low light rhizomes. and roots of these three larger species, (Pregnall et al. 1984. Smith et al. 1988). recruit to the deeper areas in summer but they do Because the ftee larger species are perennial. not survive the reduced light periods of winter growing and metabolizing all year. winter ligbi (Kenworthy 1992). attenuation will have a greater effect on them than it would on a species like Halophila These observations indicate that the depth decipiens, which overwinters in a seed bank. An zonation patterns and the inferred minimum light average annual light attenuation coefficient may requirements of seagrasses in the Gulf of Mexico be a better predictor of depth distribution for the are more complex than can be described by larger species in the more southerly latitudes of Sea-gragg itfonitoring and Research - 1992 Page 21 the Gulf of Mexico. however, we should SEAGRASS CONSERVATION AND continue to examine the concept of a critical time RESTORATION period in order to develop a more sensitive predictor for each of the species, regardless of size (Moore 199 1). For example. in more Our efforts to protect and maintain the diversity northerly regions of the gulf the annual growth and product-ivity of seagrass communities in the period of Halodule wrightii may be shortened by Gulf of Mexico will dep-end tin our ability it) St' low winter temperatures, this argues for a stain good water quality. In order to do this we must develop comprehensive water smaller time window in which light attenuation should impact seagrass growth. management plans that include functional and reliable optical water quality models that enable Even within the genus Halophila the two species resource managers to identify the parameters appear to have different requirements for growth having the greatest influence (in transparency (Dawes et al. 1986, Dawes et al. 1989). (Ki,-k 1999, Gallegos et al. 1990. 6allegos et al. Halophila decipiens will grow right up to the 199 1, Kenworthy 1992, Morris and Tomasko edge of a meadow but is rarely found growing 1993). Within a comprehensive plan, regional within the canopy of the larger species. and local resource agencies would establish Halophila engelmanni grows in the understory desirable goals for seagrass species and coverage of the larger species or in mixed beds with based on existirg and/or historical seagrass Halophila decipiens (McMillan 1985, distribution and abundance data. These goals Continental Shelf Associates Inc. and Martel would be matched with the species pool. curTent Laboratories Inc. 1985, Onuf 1991, Kenworthy, water quality conditions, and the hathyrnetry of personal observations in the Banana River. the watershed. lagoon, or estuary in order to Florida). Both species are often the deepest e,,aluate the goals with respect to the cost of dwelling but Halophila engelmanni behaves achieving such goals. An essential feature to this more like a perennial than an annual plant. plan Is a scientifically based water quality monitoring prograin that identifies a functional Based on the above discussion, w Iater quality, variable (e.g., the attenuation coefficient) for particularly water transparency, is expected to predicting seagrass species and their distribution. have a major influence on determining the In addition. the monitoring program must be species composition and abundance of capable of identifying the water quality factors seagrasses in the Gulf of Mexico. The five that control the functional variable (e.g.. DOM. seagrass species. with their diverse anatomy, TSS. C14L. and dissolved inorganic nitrogen). varying structural complexity, and widely When properly calibrated. optical water quality ranging habitat requirements. provide different models can be used to quantitatively compare the functions and values for the flora and fauna of relative contributions of the individual factors. the gulf. Presumably, seagrasses can act as a For example, a dependent variable such as the mediary in transmitting the detrimental effects of light attenuation coefficient or the percent (if surface iff adiance can he evaluated as 9 function degraded water quality to secondary production of one or several independent variables on-a and the health and well-being of fish and wildlife contour plot to estimate their relative (Kenworthy and Haunert 199 1). contributions to PAR attenuation (McPhet son and Miller 1987. Vant 1990, Gallegos et al. 1991, Deronsion et al. 1993, Gallegos and Kenworthy 1993, Gallegos In Press). This type of comprehensive. analysis provides a means for deterridning the target parameter for Seajerass Monilorin2 and Research - 1992 Pa-ve 25 management efforts needed to improve water transparency. 1rhis approach avoids the inadequacies of traditional water quality criteria and standards where single numeriLal values or vague narratives are assigned as targets for which water quality parameter values cannot be exceeded. Given the diverFay of environments and seagr&qs habitat requiT--ments known to exist in the Gulf of Mexico, a n ore flexible approach is needed. Any effort to ii ripose the same standard for water transpar !ncy in the Florida Keys, the barrier island lag(,,)ns of Mississippi. and the Laguna Madre will p.-obably fail because the species pools and factors c(,,itrciling water transparency in these coastal ecosystems are likely to be very different. Future efforts to conserve4nd restore the valuable seagrass resources of the Gulf of Mexico depend on a scientifically based understanding of the light requirements of the individual species and the environmental and anthropogenic factors affecting the submarine light regime. Research efforts should continue to ft-cus on developing scientifically based water measure water quality but also analyze and quality monitoring programs that not only interpret the parameters so that factors influencing water transparency can be evaluated for the protection of seagrasses, Searrass Moniforinz and Research - 1992 Page 26 REFERENCES Continental Shelf Associates. Inc. 1987. Assessment of hurricane damage in the Florida Big Bend seagiass beds. Final report for the F,nviron mental Studies Group. Gulf (if Mexico Regional Off ice. Minerals Management Service. New (Jr1cans, La. Contract No. 14-12-0001-30198. 38pp. + Appendices. Continental Shelf Associates, Inc. 1989. 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Seagrass depth limits. Aquatic Botany 40:363-377. Durako. M.J.. R.C. Phillips, and R.R. Uwis. 1987. Pr(xeedings of the symposium on subtropical -tropical seagrasses of the southeastern United States. Florida Marine Research Publications 42. 209 pp. Searrass Monitoring and Researth - 1992 Page 27 EIeuterius, I-N. 1987. Sea grass ecology along the coasts of Alabama. Louisiana. and Mississippi. Florida Marine Research Publications 42:11-24. Fonseca. M.S. 1993. A guide to planting seagrasses in the Gulf of Mexico. Texas A&M University Sea Grant College Program TAMU-SG-94-601. 25 pp. Fonseca. M.S.. G.W. Thayer. and W. J. Kenworthy. 1987. The use of ecological data in the implementation and management (if seagrass resioralions. Florida Marine Research Pubjications 42:175-188. Fourqurean. J.W. 1991. The roles of resource availability and resource competition in structuring scagrass communities (if Florida Bay. Ph.D. Dissenation. University of Virginia. Charlottesville. 280 pp- Fourquirean. 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The light requirements of seagrasses: proceedings of a workshop to examine the capability tit' water quality criteria. standards and monitoring programs to protect seagrasses. NOAA Technical Memorandum NMFS-SEFC-287. Kenworthy, W.J. and D.E. Haunert. 199 1. The light requirements of seagrasses: proceedings of a workshop to examine the capability of water quality criteria. standards and monitoring programs to protect seagrasses. NOAA Technical Memorandum NMYS-SEFC-287. 181 pp. Kirk. J.T.O. 1988. Optical water quality-what does it mean and how should we measure it? Journal of the Water Pollution Control Federation 60:194-198. Marsh..I.A. Jr.. W.C. Dennison. and R.S. Alberte. 1986. Effects of temperature on photosynthesis and respiration in eelgrass (Zostera marina L.). Journal of Experimental Marine Bio!ogy and Ecology 10): 257-267. McMillan. C. 1985. The seed reserve for Halodule wrighrii, S'vringodiumfilifonne and Ruppia maririnia in Laguna Madre. Texas. Contributions in Marine Science 28:141-149. McPherson, B.F. and R.L. Miller. 1987. The vertica! attenuation of light in Charlotte Harbor. a shallow, subtropical estuary in southwestern Florida. Estuarine Coastal and Shelf Science 25:721-737. Moffler. M.D. and M.J. Durako.' 1987. Reproductive biology of the tropical -subtropical seagrasses of the southeastern United States. Florida Marine Research Publications 42:77-88. Moore, K.A. 1991. Field studies of the effects of variable water quality on temperate seagrass growth and survival. Pages 42-58 in W.I. Kenworthy and D.E. Haunerl (eds), The light requirements ollscagrasses: proceedings of a workshop to examine the capability of water quality criteria. standards and monitoring programs to protect seagrasses. NOAA Technical Memorandum NMFS-SEFC-287. Morris, L.J. and D.A. Tomasko, (eds). 1993. Proceedings and conclus:o!n,317 workshops on: subincrged aquatic vegetation and photosynthetically active radiation. Special Polication SJ93-SP 13. Vilatka. Fla.: St. Ichns River Water Management District. 244 pp.+ Appendices. Neckles. H.A. 1991. Complex interactions among light-reducing variables in seagrass systems: simulation model predictions for long-term community stability. Pages 127-132. in W.J. Kenworthy, and D.E. Haunert (eds), The light requirements of seagrasses: proceedings of a workshop to examine Seaerass Monitorinje and Research - 1992 Page 29 the capability of water quality criteria, standards and monitoring programs to protect seagrasses. NOAA Technical Memorandum NMF-S-SEFC-287. Onuf. C.P. 199 1. Light requirements of Halodule vs-rightfi. S 'vringodiuntfiliforme.md Halophila engelmanni in a heterogeneous anj variable environment inferred from long-term monitoring. Pages 95-105 in W.I. Kenworthy and D.F. Haunerl (eds). The light requirements of seagrasses: proceedings of a workshop to examine the capability of water quality criteria. standards and monitoting programs (o protect seagrasses. NOAA Technical Memorandum NMFS-SF.FC-287. Penhale,. P.A. and R.G. Wetzel, 1983. Structural and functional adaptations (if ecigrass (Zostera marina L.) to the anaerobic sediment environment. Canadian Journal (if Botany 61:1421-1428. Phillips. R.C. and R. R. Lewis. 1983. Influence of environmental gradients on variations in leaf widths and transplant success in North American scagrasses. Marine Technology Society Journal 17:59-68. Pregnall, A.M.. R.D. Smith. T.A. Kursar, and R.S. Alberte. 1984. Metabolic adaptation of Zostera marina (eelgrass) to diurnal periods of root anoxia. Marine Biology 83:141-147. Smith, R.D.. W.C. Dennison. and R.S. Alberte. 1984. Role of seagrass photosynthesis in root aerobic processes. Plant Physiology 74:1055-1058. Smith. R.D.'A.M. Pregnall, and R.S. Alberte. 1998. Effects of anacrobiosis on root metabolism of the seagrass' Zostera marina L. (eelgrass). Marine Biology 98:131-14 1. Tomasku. D.A. and C.J. Dawes. 1989. 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Seagrass Monitering and Research - 1992 Page 31 SUBMERGED AQUATIC VEGFTATION MAPPING WORKING GROUP REPORT by Lawrence R. Handley National Biological Survey Southern Science Center 700 Cajundome Blvd. Lafayette, LA 70506 -Seagrass Monitoring and Research - 1992 Page 33 primary goal of this working group was to Gulf of Mexico from aerial photography review, discuss, and recommend criteria for acquired in 1983. and their wetland and upland mapping the location and extent nf submerged maps developed for each (if the coastal states aquatic vegetation (SAV) in the coastal region of include SAV. Inconsistent identification (if SAV the Gulf of Mexico as an indicator of nearshore limits the utility of these. historical weetland and environmental quality. The area under upland maps. Seagrass trend maps at a scale of consideration for this discussion is the 1: 100,000 have been developed for the Laguna Louisianan Province of Environmental Madre of Texas using 1989 field mapping and Monitoring and Assessment Program -Estuaries, master's theses for two dates. Seagrass maps which includes the coastline of the Gulf of have been developed for trends analysis for the Mexico from Brownsville, Texas. to Anclote Chandcleur Islands of Louisiana for nine time Key, Florida. This includes the coastlines of the periods, for Perdido Bay, Horida-Alahama, for states of Texas, Louisiana, Mississippi. and four dme periods. and for the NPS Gulf Islands Alabama. and the northwestern coast of Horida. Nabonal Seashore, Mississippi -Alabania-Flofida. The area of concern includes bays, sounds. and for three time periods. Seagrass mapping for estitaries from their offshore limi! to the inland four fime periods for St. Andrew's Bay, Florida. lind of asLronomical tidal influence. is in progress. Although NOAA has developed a major seagrass EXISTING MAPPING PROjECTS mapping program for the North Carolina coast. they have not mapped any areas in the Gulf of Mexico. They have been the principal instigator What maps, data, or information are available and planned by Federal and State agencies and coordinator in the development of a seagrass wPhin the Gulf of Mexico area? What is the mupping protocol. The Minerals Management areal coverage of the projects? What kind of Service funded the development of seagrass cooperation exists among agencies for each atlases for the Florida Big Bend area in 1985 and project? EMAP-Estuaries has begun a mapping the Florida Day area in 1985-1987. These atlases project of SAV within the Louisianan Province. are being done at a scale of 1: 100.000. This project will acquire 1:24,000 scale natural The NPS has funded the U.S. Fish and Wildlife color aerial photography of the Gulf Coast over Service (USFWS) to map the Gulf Islands four years. The photography will be interpreted, Nati.onal Seashore for three time periods and is mapped as overlays to U.S. Geological Survey currently developing a contract for field (USGS) 1:24,000 scale quadrangles, and inventory of seagrasses present. If funding is digitized to provide SAV acreages. The National available they will fund the USFWS to develop Biological Survey's (NBS) Southern Science seagrass maps for tht; Gulf Islands for the early Center is the project leader and is responsible for 1940's. completing the photointerpretation and mapping. Other project participants include the National The states around the Gulf of Mexico coast have Oceanic and Atmospheric Administration varied in program development related to (NOAA) for seagrass mapping protocols, and the seagrass inventory and mapping. Texas and National Park Service (NPS) and the states of Florida have active mapping programs. and Florida. Alabama, Mississippi, Louisiana. and Alabama mapped the seagrasses of MobJe and Texas for review and ground-truthing. Perdido bays in the late 1970's. but Louisiana The NBS is responsible for most of the seagrass and Mississippi have never inventoried or mapping in the Louisianan Province completed mapped their SAV (although the Louisiana to date. They prepared seagrass adases for the Department of Natural Resources Coastal Seagrass Monitoring and Research 1992 Page 34 Management Division was very active in the 0 Matches other programs (e.g., National rcview and ground-truthing of the aquatic beds Wetlands Inventory). in the 1988 USFWS wetlands habitat maps for coastal Louisiana). 0 App;ieable to county- and parish-level planning. The University of Texas Bureau of Economic Geology has mapped the entire coast of Texas 0 Used for screening permits and regulatory for SAV for the late 1950's and for 1979-1980. monitoring. Ile Texas Department of Parks and Wildlife has inventoried and mapped Galveston Bay, San 0 Widely available. Antonio Day, and Nueces Bay. They also have an ongoing project for Corpus Christi Bay. 0 Allow visualization in the field. The Florida Department of Natural Resources 0 USGS has an active updating program. has completed trends analysis for St. Andrews Day and has ongoing projects to redo the 1983 DISADVANTAGES: USFWS seagrass photographic atlases an d to establish trends for Tampa Bay. 0 Too coarse for small impacts (e.g.. prop scars. boat docks). BASE MAPS 0 Minimum of 114 acre mapping. Do we have adequate base maps? Base maps are 0 For some quadrangles only orthopho(os have a common map depiction of the coastline in a ; I been produced. common coordinate system at some level of map 0 Digital data for quadrangles lacking for many accuracy standards. such as USGS 1:24.000 areas. topographic quadrangles or 1:40,000 National Ocean Survey (NOS) nautical charts. It will be 0 Lack or submerged information (e.g.. difficult to complete historical mapping or to bathymetry). match mapping projects from one state or region to another without the application of a common 0 Many maps are outdated for changing base map series. coastlines. The 1:24,000 USGS topographic quadrangles are There are alternatives to the USGS topographic the most available and widely used base maps quadrangles as base maps. The NOS -shoreline and should be considered the minimum base manuscript maps are at scales of 1:20.000 or map, in terms of formal and scale, to be used for 1: 10,000. However, they are limited in their scagrass mapping. availability, they are not available in a digital There are advantages and disadvantages to form, and other coastal features (e.g.. marsh. working with the USGS 1:24,000 maps: cultural features, and roads) are lacVing. Other projects are dcveloring their own base maps ADVANTAGES: because the scope of the projects demands maps at scales of 1:20,000, 1:12,000. or 1:6.000. 0 USGS is the national standard. Other mapping efforts may use 1: 100,000 scale USGS base maps that cover large offshore areas Seagras@ Monitoring and Research - 1992 Page 35 iz and/or areas where detailed data are not available during photo interpretation and even slight nor deemed necessary. amounts of turbidity destroy the signature. Signature Identification: Tile photointerpreter GROUND DATA TO COLLECT IN (PI) gains confidence with repeated signature THE MAPPING EFFORT identification. That identification includes pholointerpretation and the collection (if data in What she-specific data should be collected in the the field. Although study has shown interpretation can he done without PI field field as indicators for photointerpretation? participation, it is generally recommended that Ground-truthing for SAV mapping should Ibe the PI be involved in the field effort. The PI has done by the photointerpreter. The ground- to know how the signatures correspond to SAV in the water. In addition. a PI lacking field truthing focuses on the identification of the SAV experience may no( know all the pertinent photo signature. Point-specific locations of information to ask the field worker. thus 1. questionable interpretation" are primary field affecting the accuracy of the final product. check sites, and other areas of "confidently interpreted" SAV are covered by a grid system. Nonvegmted Feature : When at a site, the field transects, or random point field check sites. person should be aware of objeas that could he There is a difference between ground data to be confused with SAV on the aerial photographs acquired as aids to photointerpretation and that (e.g., eroding peat banks, geologic formations. used as verification of the mapping completed. etc.). EMAP requires that if a monitoring location is placed in an area where seagrasses are mapped I ocation: The correlation of afield collection on the 1:24,000 quadrangles. seagrasses'must be site, transect. or plot with a location on the aerial present. Therefore. mapped seagrass beds must photographs is essential to photointerprelation be verified as present or absent through field and verification of signatures. This is even more review. The key elements in tying ground data important when looking at vegetation density to the pholointerpretation are species present, and species composition. signature identification conflirmation, . nonvegetated features, and location. Other field Density: Estimating density requires extensive data that may be collected as part of the mapping field sampling and is potentially a major effort but are not critical as aids to the resource expenditure that can limit the number of photeinterpreter in SAV delineation include sampling stations. There are two types of vegetation density, water depth. presence or density that can be estimated: 1) the ground abundance. of epiphytes, evidence of prop scars, cover approach estimates the density of SAV sediment type, light attenuation, salinity, and within a patch or bed. i.e. the percent of surface presence or abundance of macroa:gae. covered by blades and stems, and 2) the patch density approach estimates the density of patches Sp"ies Present: In most instances, species of SAV across the area. i.e.. the number. size. cannot be distinguished in a photo (although and distribution of patches compared to the there are a few exceptions). Although aerial amount of bare ground across the surface. The photographic signatures for Halophila sp. have ground cover approach is certainly the most been identified through fieldwork in water desired, but it requires considerable control in depths greater than 15 m, aerial photography is terms of scale. emulsion. water clarity. water no, practical for mapping in deep water because depth, and field work. Accurate estimation of the water often obscures detection of grass beds ground cover through pholointerpretation is not Seagrass Monitoring and Research - 1992 Page 36 always achievable because water clarity and samples may include redox readings. dry weight depth can lighten submerged vegetation, making organic content, statistics on sediment grain size. it appear less dense. Also the relation between or the percent sand. silt. and clay. Although data photographic signature and density can vary on sediment types are important in the between species and even within a species comparison of sediment type and organic content depending on blade lengLii, width, pigmentation. to submerged vegetation density and species degree of epiphytization and aspect (lying over comrx)sition. the sediment type data have little versus standing upright). To achieve an estimate application in the pholointerpretation pr(wess. of ground cover with a stated degree of accuracy requires considerable fieldwork. As a result, it is I i&ht Attenuation: Turbidity plumes in the time-consuming and expensive. Estimating water column caused by suspended sediment or patch density is more economical and feasible algae can obscure the signature of SAV. Data on through photointerpretation. thus providing light attenuation can he gathered by use of light accurate descriptions of SAV distribution. meters lowered within the water column. Such data are important in understanding the growth, Water Dep : Although not essential in the structure. and composition ofSAV. Turbidity is photointerpretation process, data on water depths easily i'dentified in aerial photographs. but, (soundings. pole measurements. bathymetric attenuation data are not essential in the maps. etc.) can aid the PI by identifying the areas identification of SAV signatures. within the optimal range for SAV growth, or by ident"fyLng dark signatures in the water as Sidinity: Although salinity can cause resulting from deep water rather than from SAV. considerable variation in SAV species Water depth at the time the aerial photography is composition. density, and growth. salinity data acquired can affect the signature of the SAV are not necessary in the identification of SAV present. The vegetation will apptar darker if the signatures. water level is low and the blades are lying over than if the water level is high and the blades are Mamalga Macmalgae take' two forms: drift more upright. algae moving with bottom currents. and attached macroalgae. generally found in shallow low- Epiphytes: The amount and type of epiphytes energy water. Although m&Toalgae are present are important field data to be collected to generally found in shallow water they may determine the health and condition of SAV, but appear darker than other SAV and often have they are very seasonal in occurrence and it is not circular patterns within the signature. More possible to photointerpret them. In addition. often the signature of macroalgae is sampling epiphytes is extremely time consuming indistinguishable from that of other forms of and would therefore require a large commiltment SAV. and field determinations are necessary. of resources. 5=: Prop scars are easily identified on low- level (e.g.. 1:6,000 scale) aerial photography. They may be mapped and their revegetation followed for subsequent time periods. They help in establishing locations on the aerial photography. Sediment L= Sinficial sediments are easily collected at field sites. Data derived from Seagrass'Monitoring and Research - 1992 Pagi 37' NEW TECHNOLOGY IN 0 GPS can reduce the amount of time needed to SEAGRASS MAPPING physically locate the bcds appearing in aerial photographs during post-flight ground surveys, The most impcrtant questions surrounding new 0 To allow for statistical accuracy. more pre- technology associated with image acquisition flight field time is required for putting out are: targets that can be seen on the photo (unless permanent visible features are already present). What remotely sensed imagery exists that we could successfully use? 9 GPS provides horizontal control of aerial 0 Ist .he remotely sensed imagery effecfive at photography and maps. identifying SAW 0 GPS solves digitization problems with * Should programs be looking at these new rectification and geopositioning because it advances in the long term? incorporates GPS digital data into the pr(wess. The working group expressed the opinion that 0 GPS-ccntrolled photography costs four-to- eventually SAV mapping should get away from five times as much as standard photography. the use of aerial photos because of the increasing. 0 Certain photos require a target present in costs and complexity of flight mission planning order to he triangulated with other photos, which and coordination. The general consensus of the increases cost and time for cm)rdina6on. working group was that, at the present time. remotely sensed imagery, i.e.. satellite and 'Me working group strongly recommended that airborne scanner data. cannot provide accurate anyone collecting point data in SAV fieldwork and consistent SAV identification. However.. the use GPS technology and perform differential group believes that future technological correction on the GPS data acquired. advances will bring scanner data on S,^ V within the realm of consideration. Therefore we should fhe use of the analytical stereoplotter is another stay current with all new technology even though ttchnological advance that can potentially he (if we may not be able to use it at this time. importance in SAV mapping because it will Use of Global Positioning System (GPS) is reduce the time required for mapping and the considered to be the most important , . . f cost,of mapping in the long term. The analytical technological advancement in the mapping of stereoplotier incorporates the use of GPS field SAV. Points to consider in using GPS include: data to rectify the aerial photography and allows 0 Aircraft navig Iation technology is advan . cing for photo interpretation and digitization in a one- rapidly and positioning using airborne GPS step process. technology allows precise location of the plane at the moment the photo was taken. CLASSI.FICATION 0 GPS provides real-time display of location and coverage of the photography collected to The primary question formulated by the working ensure acquisition of the areal coverage group was: What has been tradificinally specified. classified when seagrasses are mappcd? 0 GPS technology is advancing very rapidly. Seagrass Monitoring and Research - 1992 Pahe 38- Most historic mapping projects have simply be further classified by a range of densities of delineated the presence versus absence of patches within an area. A density classification seagrasses. because of the scale of the mapping sys(cm is presented as pan of the implementation effort. the limited funding often available, a plan for NOAA's Coastwatch -Change Analysis demanding schedule. lack of fieldwork. and lack Project (C-car@ I)ohson et al. 1994). of PI expertise in recognizing seagrass signatures. Also, the simple presence versus The I.,ouisianan Province SAV mapping absence of seagrasses allows easier replication of classification for EMAP includes a gradient of effort to determine trends of seagrass change. SAV patch densities (from continuous coverage Macroalgal presence is also identified as a through four density classes), and the presence separate category in some projects. of macroalgae beds. The working group agreed that it is better to have fewer classifications. The simpler the STRATIFICATION OF SAMPLING classification. the fewer "gray" areas for interpretation. The interpretation of seagrass Once the baseline mapping for SAV present in density has been attempted in several projects in the Louisianan Province is completed. EMAP the past, are each with inconsistent results. intends to develop a monitoring program to Generally, theintent in seagrass mapping is to assess status and trends of these habitats. describe the morphology of the be d as a whole. Because SAV beds vary widely in size. shape. not the density of seagrasses within the bed. In a and ecological charvteristics. some form of a USFWS study. prefiminary data indicated the priori stratification is necessary to ensure accuracy of interpretation of seagrass densities adequate and representative sampling. over 70% and under 30% was nearly 70%, whereas interpretation of the moderate of Sampling may be stratified by several criteiia: w4ium density range (30-70%) was approximately 50%. The classification of 0 Geographic location (distance from shore, seagrasses by species, or the separation of estuaries, river mouths. islands. behind freshwater species from seagrasses, has also been barriers. open Gulf). attempted, but it cannot be consistently interpreted from aerial photography and requires 0 Salinity (may not be repeatable from year to extensive fieldwork and ground-truthing. year as salinity can change radically). Interpretation of species composition and density is affected by the lack of homogeneity (although 0 Substrate type. turtlegrass may be interpreted with some consistency as a darker signature, other seagrass e Anthropogenic stresses (dredging. boating speci,.s are not as easily discerned and the access,, contamin&its). "species composition of mixed beds is impossible to determine from serial photography) and System size. changing water depths (as water depth increases the water signature gets darker). 0 Areal extent of SAV beds. Morphologic classification can be accomplished 0 Water depth. from aerial photography. Past projects have identified "continuous" beds (large areas of 0 Relationship to physical stress (fetch). seagrasses) and "patchy" beds (small scattered units of seagrasses). "Patchy" seagrass beds can Seagrass Monitoringr and Research - 1992 Page 39 0 Special management/jurisdiction.. Polygon shape - probably not f@asihle because of wide variation of shapes within each geographic 0 A tiered approach is suggested for the location to be sampled. stratification of sampling. Depth - ranges of depths should be sampled. FIRST TIER Sediment type - sand, silt. organic mucks. The first tier of sampling strata is based on geographic location and system size. This will MONITORING provide adequate distribution of sampling throughout all ecological systems ovailable The mapping working group suggested that the within the Louisianan Province,. Y*."MAP monitoring of SAV should: Lagoons - sounds or bays, protected by barrier Tie in with existing mapping and monitoring islands without large freshwater inflow. programs of NOAA. the NBS, state agencies. the U.S. Environmental Protection Agency Gulf of Estuaries - includes large and small systems (for Mexico Program -habitat degradation committee. sampling purposes include all systems on an and regional and county mapping programs. equal basis rather than weighting systems by areal extent). Repeat the mapping for the Louisianan Province every four years to assist monitoring. ensure Big Bend Area, Florida - unique area (open repeatabil Iity of sampling locations-and establish coastal). trends felated to 6e ecological health of the province's SAV. River deltas - freshwater to brackish SAV. Rely on the protocols developed from the 1990 SECOND TIER NOAA-sponsored seagrass workshop and the C- CAP program (Dobson et al. 1494). The second tier of sampling strata is based on seagrass bed morphology and ensures representation regardless of size, coverage, water depth, or sediment type. This tier is based, primarily, on the ability to delineate seagrasses and map them. The polygon delineates the boundary of SAV beds or patches on a map. Potential stratification variables include: Polygon clam - continuous or patchy, density of patches over area. Polygon size - ranges of polygon sizes should be formulated. Seagrays Monitoring and Research - 1992' Page 40- REFERENCES Dobson, J.E., E.A. Bright, R.L. Ferguson, D.M. Field, L.L. Wood, K.D. Haddad, H. Iredale III, J.R. Jensen, V.V. Klemas, R.J. Orth, and J.P. Thomas, 1994. N0AA coastwatch change analysis project-guidance for regional implementation. U.S. Department of Commerce. NOAA/Coastal Ocean Prograrm/Coastwatch: Change Analysis Project. NOAA/NMFS, Beaufort Laboratory, Beaufort. NC. 121 pp + 19 figures. Page 41 Seagrass Monitoring and Research-1992 ECOLOGICAL INDICATORS WORKING GROUP REPORT by Hilary A. Neckles National Biological Survey Southern Scienct Center 700 Cajundome Blvd. Lafayette, LA 70506 Seagrass Monitoring and Research - 1992 Page 43 The charge to this working group was to identify RESP ONSE INDICATORS a suite of indicators of the ecological condition of submerged aquatic vegetation (SAV) beds appropriate for long-term monitoring. Ideally, Many plant processes can he expected to respond indicators would function on a regional scale to changes in cnvironmental conditions. over a period of decades. Indicators must be. Consequently. a wide range of plant applicable across a range of SAV habitat types. characteristics should reflect environmental related to ecological condition in a way that can change. The working group generated an be quantified and interpreted, quantifiable in a exhaustive list of candidate response indicators standardized manner with a high degree of and then combined them into general categoiries repeatability. and appropriate within the for discussion. The categories in Table I were .constraints (financial, logistical) imposed bythe selected from the more extensive list by spatial wd temporal scale of a regional. long- consensus as the best indicators of habitat term monitoring program: i.e., the long-term and condition. regional variability of an indicator must not be masked by short-term or local variability. The None of the proposed indicators has been tested Environmental Monitoring and Assessment ai the regional and dccadal scales inherent in Program (EMAP) attempts to limit broad scale EMAP sampling. Seagrass beds are dynamic. data collection for indicators of envifonmental complex systems, and many of the parameters quality to a single index period per year. when used to characterize habitat condition exhibit r.esponses to anthropogenic and climatic stresses considerable temporal and spatial variability. are anticipated to De most severe (see Summers The working group agreed overwhelmingly that et al. 199 1). The overriding concern expressed to accurately assess seagrass, ecosystem by this working group during discussions of condition the EMAP sampling network should candidate indicators was the potential to yield include frequent sampling at selected permanent meaningful information if sampled only once stations. The proposed indicators would yield during the year at sites separated by kilometers. the most information on seagrass habitat status and trends if sampled along permanent transects Working group members were asked to consider established perpendicular to the depth gradient. parameters that could be measured to quantify integrated responses of SAV to individual or multiple stressors ("response indicators"), and ABUNDANtE parameters that could be measured to quantify pollutant exposure or habitat degradation Measures of plant abundance are among the most ("exposure ipdicators"). Participants were asked important indicators of habitat condition. also to recommend the optimal timing and Working group members* identi fled various methods for measurement and to suggest morphometric and population parameters that whether threshold values separating desirable tend to respond to environmental change and from undesirable habitat conditions exist for then prioritized these measures for inclusion in a candidate indicators. It became clear during long-term monitoring program. All candidate discussions that, in many areas. further research indicators are estimable from quadrat-based is necessary to improve our ability to sampling. Prioritization was based on ease of characterize SAV habitat condition over broad measurement, predictability of response to spatial and temporal scales. environmental stress. and degree of temporal and spatial variability (Table 1). Abundance measures should be added to a monitoring Seagrqvs Monftoring and Research - 1992 Page 44 program in order of priority as resources permit. Shoot density: Density decreases predictably with declining availability of light and sediment nutrients and is less subject to variability caused by grazing than are other measures of abundance. Shoot density has historically been one of the most frequently measured parameters of seagrass populations. Thus. a long-term data base for seagrass density under varying environmental conditions exist- in the literature from which thresholds of responses could probably be generated. Because seagrass species RESPONSE INDICATORS differ in their susceptibility to environmental stress and competitive interactions, a record of Abundance Shoot density by species densities of individual species would yield more SAV biomass information than would a record of total Algae biomass macrophyte density. For example. among Leaf width tropical seagrasses, Thalassia is the most Leaf area index sensitive to certain environmental stressors and Plant consituents is the strongest competitor for nutrients. An Soluble carbohydrate concentration increase in density of other seagrasses could thus Ratio of C:N:P signal a decline in environmental condition if Species composition coupled with a decrease in eensity of Thalassia. Seagrass Macroalgae SAV Biomass: Although susceptible to the Filamentous algae confounding effect of grazer leaf removal, Depth limit of bed biomass integrates leaf length and width and Genetic diversity therefore may be more responsive to Stress proteins environmental stress than leaf morphometry. Animals Productivity The allocation of resources between aboveground and belowground biomass can also yield insight into environmental stressors. EXPOSURE INDICATORS Light Algal Biomass: Algal growth is frequently Nutrients correlated with nutrient enrichment. such that Total nitrogen, total phosphorus high biomass of either epiphytes or unattached Ammonuium, nitrate, soluble reactive phosphate macroalgae may signal declining water quality. Dissolved oxygen Algal biomass is a result of interactions among Physical conditions many abiotic and biotic controls. however, and Physical energy regimie Sediment characterstics ordinarily exhibits extreme temporal and spatial variability. Therefore, environmental condition cannot be interpreted definitively from algal biomass alone. To improve the utility of algal Table 1. Ecological indicators proposed for inclusion in the EMAP biomass as an indicator of SAV condition. sampling network research is particularly needed to elucidate the complex interrelationships among light availability, nutrient concentrations, grazing intensity, and algal response. Seagrass Monitoring and Research - 1992 Page 45 Leaf MoWhomcU3t: Leaf width can be used to environmental conditions, insufficient data exist diagnose environmental changes within to assign critical levels for any seagrass species. 77ialassia populations; in general, declining leaf Research is needed to determine thresholds of widths suggest environmental stress. constituent concentrations indicative of Information does not exist, however, to Werpret environmental stress. differences in leaf width among populations. Therefore. leaf width should be considered as a Constituent concentrations in SAV tissue will be local response indicator for Thalassia when the most useful for evaluating environmental monitored at permanent stations orly. Since leaf conditions. There may be some benefit in width varies with shoot age as well as with sampling C:N:P ratios of macroalgae also. as an environmental conditions, trends in other index of recent water-column nutrient response and exposure indicators should be availability. Despite the ephemeral nature of considered to help interpret any temporal macroalgal growth, repeated sampling over changes in leaf width. Before leaf width is broad geographic areas might be useful to detect considered as a geographic indicator. further patterns of nitrogen and phosphorus loading. research is needed to quantify the spatial van ability of this parameter its relationship to environmental gradients. SPECIES COMPOSITION Leaf Area Index: LAI integrates leaf size and The physical and chemical requirements of SAV density and thus may be more responsive to species differ, making SAV species composition stressors than leaf width alone. The effort a good indicator of environmental conditions. required to determine LAI manually, however, The species composition of existing macro- and reduces the utility of this measure for large-scale filamentous algal communities can also yield manual sampling. A meter that measures LAI by information on habitat quality. The presence of light obstruction is currently used in terrestrial Enteromorpha. for example, may indicate systems and is adaptable for underwater nutrient-enriched waters. Little is known about applications. Research is needed to determine the species response of epiphytic microalgae. whether such a meter can be calibrated reliably primarily diatoms. to specific conditions. aquatic systems. Instrument-automated LAI measures may thus be available in the future. DEPTH LIMIT Declines in cover of submerged macrophytes PLANT CONSTITUENTS associated with degrading water quality usually occur first at the deepest edge of the beds. The Concentrations of soluble carbohydrates and depth limit of a grass bed is thus a reliable ratios of C:N:P in plant tissue generally reflect indicator of environmental quality; shoreward environmental conditions. For example. migration of the edge of the bed over time carbohydrate concentrations in 7halassia have indicates a decrease in the availability of light at been shown to decline with light limitation. depth. Scuba diving is most often used to locate Because concentrations of chemical constituents the outer lirnit of a grass bed. Most of the also show considerable seasonal variation, seagrass communities in the Gulf of Mexico samples for comparative purposes must be exist in water shallow enough to use scuba for restricted to similar times of year, plant growth bed delineation. Alternatively. an underwater phases, and tissue types. Although a long-term video camera can be mounted on a sled and change in soluble carbohydrate concentrations or pulled behind a boat. Use of remote sensing C:N:P ratios at a site would indicate a change in technology is the only practical technique for Seagrass Monitoring and Research - 1992 'Page 46 locating the edge of deeper grass beds such'as STRESS PROTEINS those in Florida's Big Bend region. Side scan sonar may offer a second remote sensing Stress proteins are a group of compounds that are technique for determining the presence of highly conserved evolutionarily and that form in vegetation in deeper waters. The potential to response to sublethal stresses. The use of stress map distributions of seagrasses on the U.S. west proteins &-, condition indicators stems primarily coast has been investigated using this technique. from crop research. where high levels have been Further research is necessary to determine the correlated with such stresses as anoxia and applicability of side scan sonar to the Gulf of repeated metal toxicity. The applicability of Mexico. The mixed species composition of stress proteins for monitoring seagrass condition seagrass communities may limit the utility of is unknown. Research is needed to determine the this technique in Gulf waters. as it is unlikely environnien!al factors and duration of exposure that side scan images would allow species eliciting stress protein expression in seagrasses, determinations. as wel I as the thresholds of response indicating degraded habitat conditions. GENETIC DIVERSITY ANIMALS Ile magnitude of genetic variability within plant populations is a function of en,,ironmental, Animals exert strong direct and indirect demographic, and genetic v;ents. Genetic influences on many of the macrophyte diversity is necessary for long-term persistence parameters proposed as ecological indicators. of populations and a6srstadon to changing For example. urchin grazing can directly reduce environmental comitions. A decline in genetic leaf height and biomass. Alternatively, by diver;ity may signal reduced resistance to controlling accrual of epiphyte biomass, environmentai stresses and disease. Gel mesograzers can indirectly regulate macrophyte electrophoresis surveys of specific loci have biomass, growth. and long-term survival The been performed for seagrass beds. Although importance of higher order interactions in the hiomolecular techniques for extraction and control of macrophyte dynamics argues for the fingerprinting of scagrass DNA are currently in inclusion of meso- and macrograzers in any research and development stages, rapid advances monitoring program; without information on in forensic technology and applications suggest, animal population densities it will he difficult to that routine genetic processing of biological ascribe changes in macrophyte and epiphyte material will soon be commercially available. characteristics unequivocally to habitat ne incorporation of genetic diversity into a conditions. Grazers exhibit such extreme seagrass monitoring program is dependent on the temporal and spatial variability that availability of technology to process large incorporation into a monitoring program using numbers of samples for genetic composition. widely spaced, infrequent samples would yield However,,starch gel electrophoresis of isozymes little information. However, monitoring grazers is well-established for Zostera marina and at concurrent with epiphyte and macrophyte least 1000 samples a week can be processed parameters regularly (e.g.. monthly) at easily. permanent stations representative of larger geographic areas would, contribute substantially to the understanding of local and regional habitat trends. Seagrass MonftonLnj and Research - 1992 Page 47 r PRODUCTIVITY elucidation of the complex interrelationships among light availability, nutrient concentrations, Leaf productivity responds rapidly to changes in epiphyte biomass and composition. macro- and environmental condit.ions, and it is mesograzer activity, and macrophyte response. straightforward, albeit labor-intcnsive, to measure using leaf-marking tectmiques. Because of seasonal variability in productivity, annual LIGHT sampling is insufficient to detect regional or long-term trends. If sampled at the appropriate The most important indicator of seagrass habitat time scale, however, this parameter may be one quality is the availability of photosynthetically of the most diagnostic early indicators of active iadialion (PAR) at depth. PAR should he environmental change. Monthly productivity monitored continuously at permanent stations. measurements at representative permanent The sampling array for each station consists of a stations would provide an excellent assessment data logger connected to two spherical sensors of local conditions. offset vertically and separated h, '- 0.25 - 0.5 m. depending on water clarity (see also Morris and Tomasko 1993). The sensors will have to be EXPOSURE MICATORS cleaned regularly. The frequency of maintenance visits required will be site specific-, the maximum interval between cleanings will Most of the parameters that stress seagrass probably be two weeks or less. Light is already populations exhibit extreme temporal variability, monitored intensively at several sites in the Gulf so that single, annual samples would yield no of Mexico as part of ongoing research efforts. information on the extent of pollutant exposure EMAP should attempt to collaborate with these or habitat degradation present. Working group existing programs.- members agreed that the only way to quantify habitat quality in terms of many of the most Technology is also available for continuous important stress variables is by frequent monitoring of chlorophyll concentration and sampling or continuous monitoring at permanent turbidity. These measurements should be stations. The number of permanent stations coupled with light monitoring as funds permit, established would be dictated by funding. Station location should be stratified by degree of anthropogenic impacts. Sites close to urban NUTPUENTS areas are the most suscepdble to change, and sites away from urban areas can provide baseline Nutrient enrichment enhances growth of data forIcomparison. phytoplankton and epiphytic algae, and therefore can indirectly lirnit the amount of light reaching Although it is possible to list exposure variables leaf surfaces. Dissolved nutrient concentrations that are correlated with seagrass health and are subject to considerable temporal variability, therefore should form part of a monitoring data are most meaningful if derived from program (Table 1), scientific understanding of frequent samples, Ideally, water quality should the causal relationships between multiple be measured at the same permanent stations used environmental stressors and macrophyte for,continuous light monitoring. ne need to response is limited. The need for further visit sites regularly for light sensor maintenance research to validate the proposed variables as provides at least biweekly opportunities to take exposure indicators cannot be overemphasized: water samples. Samples should be analyzed for the evolution of seagrass management requires Seagrass Monitoring and Research - 1992 Page 48 total nitrogen. total phosphorus, nitrate, may be assisted by classifying sampling sites ammonium, and soluble reactive phosphate. according to energy regime and sediment characterisfics. Valuable data for such To provide a spatial assessment of nutrient postsampling stratification include wave energy concentrations and the potential sources of density. physical exposure index. effective fetch. nutrient enrichment, frequent water quality tidal current velocity, sediment depth. sediment sampling at a small number of sites should he grain size distribution. and sediment carbonate coupled with annual or semiannual sampling at and organic contents. all of the sites forming the EMAP network. All nutrient sampling should be restricted to a 6-8 week window. The precise timing of nutrient sampling should be determined from existing records to minimize confounding effects of temporal variability. Ideally, periods of maximum and minimum runoff should both be included for each site in order to identify potential extremes of nutrient concentration, Samples should be analyzed for chlorophyll in addition to those nutrients identified for frequent sampling. DISSOLVED OXYGEN The diel fluctuation in dissolved oxygen concentration is an index of ecosystem health. Hypoxia limits secondary producers directly, and effects may also cascade to seagrasses by limiting grazers and consequently enhancing epiphyte growth. Dissolved oxygen should be measured continuously at each sampling site long enough to characterize the magnitude of diel variation and the duration of hypoxic conditions. Pilot tests of up to a week of continuous measurement should be undertaken at a limited number of sites to determine an appropriate monitoring interval for use in regional sampling. Continuous PAR monitoring at the same sites as oxygen measurement could assist in interpreting temporal and spatial patterns of oxygen concentration. PHYSICAL CONDITIONS Most of the seagrass parameters considered as response indicators are affected by physical conditions. Interpretation of response variables Seagmss Monitoring and Research - 1992 Page 49 REFERENCES Morris, L. J. and D. A. Tomasko (eds.). 1993. Proceedings and conclusions (if workshops on: submerged aquatic vegetation and photosynthetically active radiation. Special Publication SJ93-SPI3. Palatka, IFL: St. Johns River Water Management District. 244 pp. + Appendices. Summers, J. K., J. M. Macauley, and P. T. Heitmuller. 1991. Implementation plan for monitoring the estuarine waters of the Louisianian Province - 1991 demonstration. EPA/600/5-91/228. U.S. Environmental Protection Agency. Office of Research and Development. Environmental Research Laboratory, Gulf Breeze, FL. 160 pp. Seagrass Monitoring and Research - 1992 Page 50 SUBMERGED AQUATIC VEGETATION RESEARCHNEEDS WORKING GROUP REPORT by William L. Kruczynski and David A. Flemer U.S. Environmental Protection Agency Environmental Research Laboratory Sabine Island Gulf Breeze, FL 32561 Seagrass Monitoring and Research - 1992 Page 51 The purpose of this portion of the workshop was may he proportional to nutrient concentr.at ions. to identify and prioritize research requirements Thus. although there is agreement that light is for submerged aquatic vegetation (SAV) the principal controlling mechanism. it is ecosystems and give some direction to the U.S. necessary it) quanfify the relationship hetween Environmental Protection Agency concerning light, nutrients. phytoplankton standing crop and which research issue could be addressed with species composition. suspended sediments. 1992 fiscal year funds. This working group also color. macroalgae and epiphyte standing crop discussed problems associated with designing, and specie-, composition. and grazers for each implementing. and interpreting an assessment SAV community in different geographic areas, program (Environmental Monitoring and Assessment Program; EMAP) for SAV Research to establish the minimal ecological communities.. requirements must be multifaceted and should proceed in two directions to determine: ESTABLISHMENT OF 0 Ile causes and mechanisms of light ECOLOGICAL LIMITS reduction; and. 0 How plants and their community respond to There was general agreement among the changes in the quality and quantity of light and members of the working group that the quality other ecological stressors. and quantity of light are the principal ecological factors that control the presence and growth of Information is needed on the effects of stressors SAV and that light requirements for subtropical on plant morphology and carbon balance. Also, SAV species have not been adequately the association between nutrients and light determined. Also, the minimal ecological availability must be quantified. requirements for establishment and growth of SAV species are species-specific and may vary Research must @be 'performed in the field and in geographically within the range of a species. the laboratory (mi-rocosms and mesocosms) Data on northern species (e.g.. Zostera in through manipulation of environmental Chesapeake Bay) are not directly transferable to variables. Results must be modeled and their predictive models for southem, subtropical predictability tested. Research is required on systems (e.g., Vialassia in Florida Bay). Many development of culture methods for subtropical more species of SAV exist in warmer waters, species of seagrasses before mesocosms can he which compounds the problem of establishing used to establish and test limits to growth. ecological limits for SAV communities. Further, species found in coastal waters stained by organic acids probably have different ecological RESTORATION requirements than do different species or the same species growing in spring-fed waters. Restoration and creation of Thalassia and other Light requirements cannot be considered alone. SAV communities was discussed at length and it because the availability and quality of light are was concluded that there are no documented controlled by other environmental factors. examples of successful replacement of a Absorption of incident light can occ-ir as a result 71lialassia community. Once Thalassia tef water column attenuation and macroalgae- disappears from an area, it will take a long time epiphyte attenuation. The amount of light- for that area to recover. The reasons for poor absorbing phytoplankton and epiphytic growth recovery. whether the area is planted or not. are Seagrass, Monitoring and Research- - 1992 Page,52 many and complex. Resuspension of sediments The second research pToject discussed concerned in unvegetated are&s and changes in sediment establishment of the absolute maximum depth chemistry are primary factors that inhibit for each SAV species throughout its geographic colonization by Thalassia. The working group range. Physical wid chemical measurements concluded that all existing 77talassia meadows taken over the depth distribution could he used must he preserved and that no losses of "climax" to establish minimurn ecological requirement.,; SAV species caused by development should he for each species, tolerated. General concern was expressed over Hatodule is a pioneer species of seagrass that extrapolation of measurements @wd observations may recolonize a site within several growing determined on tine scale to other scaics. It was seasons. Once a bed (if Halodisle is established. agreed that scaling experiments must he so:diments become stabilized and the area may he performed before generating predictive models invaded by Thalassia. Species. population. and based upon site-specific observations or community responses during declire may not he mesocosm manipulations. the same as those observed during recovery of an SAV community. Research is required to define The following is a list of the highest priority optimum conditions for revegetalion by SAV SAV research given by each member of the species and determine plant. population, and working group. Although specific research community parameters indicative of declining topics were later consolidated into broader areas. and recovering systems. there is a N-nefit in reproducing the complete list here to identify the range of specific topics that were identified. Also, although many topics SPECIFIC RESEARCH TOPICS listed appear nearly,duplicative. there is a benefit inlisting the slightly different emphasis that differew scientists gave to areas of similar The working group identified 'specific research concern. projects for consideration for future funding, two of which were discussed in some detail. First, it was suggested that a detailed mapping and monitoring program could be used to identify Priority Research Topics research priorities. If SAV communities are 1. Quantify minimum and optimum mapped on a regular basis. areas of decline. may physical and chemical requirements for he detectable before vegetation completely all SAV species. disappears. Research could then be initiated to assess ecological conditions and identify 2. Quantify the link between nutrient input indicators of stress at various levels of ecological and light regime in different near-coastal organization. It was noted that there appears to systems. be a strong empirical correlation between presence of fringing emergent wetland 3. Establish the "lethal dose" that results in communities and presence of SAV communities. a declining SAV community. Regional mapping efforts are required to substantiate this observation and, if documented. research must be performed to establish the 4. Identify the suite of environmental mechanisms controlling this phenomenon. variables that best predicts the @ abundance and survival of SAV species. Seagrass Monitoring and Research - 1992 Page 53 5. Identify and quantify combinations and flowering. Is increased flowering an interactions of environmental parameters indicator ofstrcss'? that control SAV distribution and abundance. 15. Niap distribution of SAV species over the entire region and overlay with 6. Identify the interaction of suhlethal and regioral maps of depth. currents. lethal effects on SAV communities that nutrient loadings. sediment plumes. and are associated with water and sediment other siressors. Use mapping exercise a-,; quality. a hypothesis-gencrating tool and determine multivariate response surface 7. Investigate mechanisms of recovery of for each species. seagrass ecosystems including comparison of the relative importance of 16. Analy7c all existing information and sexual and asexual propagation and make best estimate on indicators of community succession. stress and thresholds. 8. Determine whether remotely sensed sea 17'.. Investigate the potential impact of turtle distribution can be used as an changes in sea levels to stagrass approximation of distribution of distribution. seagrasses. 18. Determine the framework for 9. Assess the usefulness of carbon balance extrapolation of measurements made on of plants in detecting stress caused by one scale to other scales. subtle changes in water or sediment chemistry that may otherwise be 19. Investigate the biology and ecology of undetectable. Halophila spp. Species of Halophila have not received much research 10. Monitor genetic differences within a attention and maj be important to plant species, because they may result in sediment stability. food chain regional differences in tolerance of productivity. and ecosystem dynamics. physical and chemical parameters. Research topics were grouped into rive main 11. Investigate the intensity of plant areas and summary statements were made to reponses to alterations of light quantity consolidate individual areas of concern. Major for SAV species. areas of required research were summarized in a model that identifies important stressors to SAV .12. Quantify response of entire seagrass ecosystems (Fig. 4). Research efforts are community, including fisheries required to identify and quantify responses at productivity, to nutrient loading. various levels of ecological organization to environmental stresses. including determination 13. Quantify the effects of epiphytes. of thresholds. epiphyte grazers, and macroalgae on seagrass survival and growth. 1. Physiological responses of plants to ecological factors. 14. Determine the impact of stressors on the balance of vegetative multiplication and a. Determine the physiological responses of SAV species to Seagrass Afoniloring and Research - 1992 P@ge 54' various levels of stresses. Does over? plant sensitivity change 0 Does Halophila enhance seasonally? hiodiversity and abundance? * Is it a good indicator of b. Identify a suite of plant-level ecological conditions! responses.to evaluate sublethal stresses so that environmental C. Investigate the effects of controls can he implemented macroalgae in light attenuation. before thresholds of population decline and change in d. Determine the relationship community structure are between nutrient levels and reached, community structure. C. Investigate the interaction 4. Mapping exercises. hetween light intensity and light quality. a. Develop regional maps of SAV distribution and physical and d. Determine the response surface chemical parameters to generate of SAV to temperature, salinity, hypotheses and predications and 'light. concerning the effects of stressors. 2. Responses at population level. 5. Overriding factors. a.. Quantify the species-specific, water quality and light a. Research is required to requirements and their distinguish between natural and interaction on long-term anthropogenic changes in maintenance and establishment seagrass distribution and of SAV species. community structure. Natural cycles and ir pacts of episodic b. Determine the mechanisms of,. events must be considered. recruitment. Analysis of long cores may be useful in detecting changes in 3. Responses at community level. community structure and correlating with historical a. Determine the interaction of events. Does succession or do epiphytes. epiphyte grazing. episodic events control species, and nutrient loading on growth dominance? What is the and survival of SAV species. temporal scale of responsc? b. Investigate ecological variables b. The management policy should and functions of communities he no net loss of climax SAV dominated by Halophila spp. species because conditions required for their recruitment are 9 Does Hatophila stabilize difficult or impossible to sediments? replicate. 0 How rapidly does it turn Seagrass Monitoring and Resiarch 1992 Page 55 Geographic CoveraL:e/D;s:r,bu1iyn M a pp ing Exercise j -0(-"hot spots" /V N'tinimum and OPI-MLIM Watershed Light Requirnnerr, Impacts Color4) Macroalgae Phytoplankton 'Spec es - Epiphytes Specific .@hanges Total 'Suspende Solids e. g., Halol)hild sp. Facrors@ Dissolved oxygen V --Er);Ph,. !es Carbon dioxide 414'f Produ Temperature Ca(hor,- 5'.1611V Nutrients Toxins L o s s Figare 4. Summary of areas nf research emphasis for SAV communlUeq. All areas must considerscale. time. and space components. Seagrass Monitoring and Research - 1992 Page 56 c. It is necessary to determine the. environmental assessment program must be effects of watershed sensitive to the fact that it is extremely difficult management and nutrient and it) distinguish changes that result from salinity effects on light regimes andiropogenic causes. natural successional in estuaries and near coastal processt--s. or long- or short-jern) variations in waters. climatic conditions. In many cases, there is not enough information on (he response of SAV d. Scaling considerations are species to various stressors to determine the necessary.to allow confidence in causalio of SAV decline. For example-allhough predictive models. disease (e.g.. caused by LabYrinthula sp.) is known to play an important role in the demise of e. The effects of meadow celgrass (Zosiera) (in the North Atlantic coast -ase organisms fragmentation on ecosystem and Europe, it is no( clear if dise function must be deteimined. play a similar role for subtropical seagrass, What is the minimum patch species. Further. the association between other size? Do many smV patches environmental stresses and incidence of disease funcdon as wel! as a continuous must be determined and quanfified. meadow? A monitoring and assessment program must also f. New and emerging technologies. be sensitive to the fact that SAV species may such as DNA fingerprinting. respond to stressors slowly and (hat should be applied to seagrass environmental conditions observed when the communities., decline is observed may not represent the same conditions that initiated the decline. Because of g. Genetic diversity of-SAV this time lag. natural SAV communifies may not species must be maintained in be goood indicators of current environmental transplant efforts. perturbations. However. they are excellent integrafive indicators of long-term ecological conditions. ENVIRONMENTAL ASSESSMENT Environmental assessment programs (e.g..' EMAP) must be carefully designed so that they have the sensitivity required to detect changes (deterioration or improvement) in environmental conditions. Careful consideration must be given to the selection of ecological indicators to assess the status of the "health" of SAV ecosystems. 'Me nature of environmental problems and their indicators may change with regions and Vmies. IMus, preparing a plan to assess the status of seagrasses; in a large geographical area is not a simple mauff. Once a problem has been identified, the next Step is to determine the causes of the problem. An Seagrass Monitoring and Research - 1992 Page 57- r SEAGRASS CONSERVATION IN THE GULF OF MEXICO: AN ACTION AGENDA SUMMARY OF WORKING GROUP REPORTS by Hilary A. Neckles National Biological Survey Southern Science Center 700 Cajundome Blvd. Lafayette, LA 70506 Seagrass Monitoring and Research - 1992 Page 59 Following a day and a half spent summarizing Works hop participants reconvened in a plenary knowledge of mapping. monitoring, and research session to consolidate the four groups of on seagrass habitats, workshop participants conservation objectives into a single aclion reorganized to translate this information into agenda. The following actions were concluded specific actions necessary to reduce habitat to represent the four highest priority ol@jectivcs degradation. Four working groups met to for conservation of Gull'of Mexico scagrass address the question, "What can our agencies and systems. institutions do together to begin, to reverse the trend of seagrass loss in the Gulf of Mexico?" Each group was asked to develop, by consensus, ESTABLISH A POLICY OF NO a list of the four highest priority actions for SEAGRASS LOSS seagrass conservation. Proposed actions were to adhere to the following four criteria: 1) actions The National Wetlands Policy Forum must lead to significant habitat improvements; - 2) it must be possible to verify or measure recommended that United States adopt a policy whether actions have been accomplished. 3) of "no net loss" of wetlands. to be achieved responsible parties must be willing and able to through compensatory mitigation for all undertake the proposed "ctions. and 4) any permitted habitat conversions. This poijzy necessary financial resources must be available. implies a 1: 1 replacement for all permitted losses Yorking groups were given 1.5 hours to produce so that the net wedand acreage remains constan!. their lists. The short time frame serveJ to focus It is exceedingly difficult, however. to working group attention on the most urgent successfully establisli seagrass beds, so that conservation needs. compensatory mitigation has not yet been effective for this habitat. The best way to ensure no ne! !oss of seagrass systems is thus to avoid As a springboard for discussion, each working group developed a fairly exhaustive list of impacts altogether. Written policy must allow potential conservation actions. Individual no loss of existing seagrass communities suggestions fell into the categories of water through any permitting programs. This is quality improvement, public education, habitat particularly important in the case of Thalassia restoration, regulation. enforcement, research, beds. which are the most difficult to establish coordination, monitoring, and seagrass through planting. 71alassia population growth sanctuaries. Various approaches were used and coverage rates are very slow, so that it takes within working groups to reach a consensus on many years for transplants to coalesce. The the top priorities, including combining like potential for physical disturbance, biolurbation. statements into inclusive conservation objectives and depletion of fauna in the interim further and ranking proposed actions by democratic reduces the likelihood of establishing a vote. The final lists from each working group functional Thalassia meadow through are presented in Appendix 1. transplanting. Therefore, permitted conversions of Thalassia beds invariably result in a net loss As evidenced by the high degree of overlap of seagrass. To date, no examples of successful among the lists generated independently by each replacement of 7halassia habitat have been work group. seagrass expens generally agree on documented. The only way to avoid reductions the immediate courses of action necessary to in total Thalassia acreage through the permit reverse habitat losses in the Gulf of Mexico. process is to stop all permitted losses. Seagrass Monitoring and Research - 1902 Page 60 designed not only to disseminate informition, IMPROVE WATER QUALITY but also to encourage public participation in seagrass conservation. For example. regional The primary cause ot&clines in seagrass habitat and local programs should he developed to is deterioration of water quality. Restoration of includu citizens in monitoring and re-,;toration seagrasses to historical levels in the Gulf of activities. The words (if a vocal seagrass Mexico will require widespread water quality constituency can translate into legislative improvements, which in (um will require support for necessary conservation measures. reduction of anthropogenic nutrient and sediment loading. Nblic and legislative support for necessary changes in watershed management FORM A SEAGRASS WORKING could be gained through the development of GROUP TO DEVELOP POLICY demonstration projects linking specific AND IMPLEMENT DECISIONS reductions in nutrient discharge or sediment inputs with seagrass recovery. Research is Effective seagrass conservation requires the needed to define the minimum water quality cooperative efforts of Federal, State. and local requirements of subtropical seagrass species and the sources of water quality degradation. thereby agencies, research institutions. and various user providing targets for management efforts. groups. A coordinated approach to Gulf (if Minimum water quality requirements can be Mexico scagrass habitat conservation should be formalized through establishment of a working derived from empirical relationships between group representing all interests. A lead water quality gradients and seagrass distribution. coordinating agency must be selected to as has been done in the Chesapeake Bay (Dennison et al. 1993), and the factors facilitate interaction among representatives and contributing to water column light attenuation to act as a clearinghouse for information: The can be determined from models relating optical SAV Working Group of the Chesapeake Bay properties of the water to specific water quality Program serves as a model for coordinated parameters (Gallegos eta]. 199 1). Experimental efforts of scientists, resource managers, research should be promoted to elucidate the politiciansi and the public. collaboration among causal relationships between environmental the interest groups resulted in the development variables and seagrasses at various temporal and of baywide ard regional submerged aquatic spatial scales. vegetation water quality requirements and distribution restoration targets (Batiuk et al. 1992). DEVELOP PUBLIC EDUCATION PROGRAMS Ugislative initiatives to protect and restore Gulf of Mexico seagrass communities depeLA ultimately on strong public support. Education programs must be developed to increase public awareness of and appreciation for the ecological and economic values of seagrass habitats. Public appreciation for natural resources is enhanced by involvement. Programs should therefore be Seagrass Monitoring and Research - 1992 Page 61 REFERENCES Batiuk.R.A..R.J.Orth.K.A.M(x)rc,W.C.IXnnison.J.C.Steveilslwr.l..W.Siztvcr.V.(,arier.N.B.Rybicki. R.E. Hickman, S. Kollar, S. Bieber. P. Heasly. 1992. Chesapeake Bay submerged aquatic vegetalion habitat requirements and restoration targets: A technical synthesis. U.S. Unvironmental Proleclion Agency, Chesapeake Bay Program, CBP/TRS 83192. Dennison. W.C., R.J. Ch1h. K.A. Moore, J.C. Stevenson. V. Carter. S. Kollar, P.W. Bergstrom. and R.A. Batiuk. 1993. Assessing water quality with submersed aquatic vegetation. Bioscience 43:96-94. Gallegos, C.L., D.L. Correll, and I Pierce. 1991. Modeling spectral light available to submerged aquatic. vegetation, Pages 114-126 jjU W.J. Kenworthy and D.E. H-3unerl (eds.). The light requirements of seagrasses: proceedings of & workshop to examine the capability of water quality criteria. standards and monitoring programs to protect seagrasses. NOAA Technical Memorandum NMYS-SE-FC-287. Seagrass Monitoring and Research - 1992 Page 62 APPENDIX A Highest priority actions for seagrass conservation in the Gulf of Mexico. as determined by individuaI working groups. Group I � Develop, fund, and implement cost-effective sewage and storm water treatment Systems. � Establish a written seagrass policy and an implementation plan including research. agency. and public interests. � Develop a baseline of information on seagrass distribution and abu ndance for the Gulf of Mexico. 0, Develop and coordinate a system of citizen advisory, public education, and monitoring groups across the Gulf of Mexico. Group 2 0 Demonstrate the linkage between improvements in point source discharges and seagrass community response at specific sites.. 0 Reduce point source and non-point source nutrient and sediment loading to attain defensible. historical values of light attenuation for individual estuaries. 0 Develop legislative and public support for seagrass systems through education. 0 Require that local comprehensive plans include potential impacts to seagrass ecosystems. Group 3 0 Actively support the preservation and restoration of seagrass habitats. 0 Establish a seagrass management working group with scientific. management, regulatory, and user group representatives to devel - p policy and a strategic management plan for the Gulf of Mexico grassbeds. 0 Build a seagrass constituency by increasing public and user group appreciation of the importance of Seagrasse.s. 0 Improve the water quality of seagrass habitats. Seagrass Monitoring and Researeh 1992 Page 63 (Appendix A, continued) Group 4 0 Change no net loss to no lois of seagrassLs because miligation and enforcement are not effective. * Promote experimental research and mapping at various scales to determine causes of habila, loss. 0 Revise and enforce water quality criteria to protect submerged aquatic vegetation. * Encourage enforcement of existing laws. policies, and rules through public education. Seagrass Monitoring and Research - 1992 Page 64 (;0% ER%%tt,%T rRr%TING OFFICE: 1"S 6W(W%!(M'40 DATE: END FILPAE I L5 10 95 NTIS Reproduced by NTIS National Technical Information Service U.S. Department of Commerce Springfield, VA 22161 This report was printed specifically for your order from our collection of more than 2 million technical reports. For economy and efficiency, NTIS does not maintain stock of its vast 0 U 4-j > collection of technical reports. Rather, most documents are printed for OP4 a' each order. 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