Ecological Functions of Nearshore Hardbottom Habitats in East Florida: A Literature Synthesis June 2009 Prepared for: Bureau of Beaches and Coastal Systems Florida Department of Environmental Protection 3900 Commonwealth Boulevard, M.S. 300 Tallahassee, Florida 32399 Prepared by: CSA International, Inc. 8502 SW Kansas Avenue Stuart, Florida 34997 Ecological Functions of Nearshore Hardbottom Habitats in East Florida: A Literature Synthesis June 2009 Authors: Kenyon C. Lindeman Department of Marine and Environmental Systems Florida Institute of Technology Melbourne, Florida Daniel A. McCarthy Department of Biology and Marine Science Jacksonville University Jacksonville, Florida Karen G. Holloway-Adkins East Coast Biologists, Inc. Indialantic, Florida David B. Snyder CSA International, Inc. Stuart, Florida Prepared for: Prepared by: Bureau of Beaches and Coastal Systems CSA International, Inc. Florida Department of Environmental Protection 8502 SW Kansas Avenue 3900 Commonwealth Boulevard, M.S. 300 Stuart, Florida 34997 Tallahassee, Florida 32399 Acknowledgments The genesis, funding, and review of this project were made possible by the Florida Legislature through the Florida Department of Environmental Protection Bureau of Beaches and Coastal Systems Beach Management Funding Assistance Program. The report was prepared under contract to PSBJ. We thank the project’s Technical Advisory Committee (TAC) for their assistance and editorial comments throughout the project. TAC members included Martin Seeling, Roxane Dow, and Vladimir Kosmynin (Bureau of Beaches and Coastal Systems), Cheryl Miller (Coastal Eco-Group Inc.), Don Deis (PBSJ), Jeff Beal and Dr. Robin Trindell (Florida Fish and Wildlife Conservation Commission), Terri Jordan (U.S. Army Corps of Engineers), and Jocelyn Karazsia (National Marine Fisheries Service). At CSA International, Inc. (CSA), we thank Melody Powell for proofreading and editing the entire document and Karen Stokesbury for coordinating document production. Keith VanGraafeiland and Chris Dean at CSA also assisted with aerial imagery and nearshore hardbottom acreage estimates. Staff from agencies and consulting companies, including Ken Banks (Broward County Department of Environmental Protection), Brian Flynn (Miami-Dade Department of Environmental Resources Management), Brian Walker (National Coral Reef Institute, Nova Southeastern University Oceanographic Center), Janet Phipps and Carmen Vare (Palm Beach County Department of Environmental Resources Management), and Quin Robertson (Coastal Planning and Engineering, Inc.), also provided estimates of hardbottom acreage. We gratefully acknowledge Julia Goodman (Jacksonville University) for the hours she spent compiling lists of invertebrates encountered in the various studies we reviewed. We thank Gerry Pinto (Jacksonville University) for developing the draft of the arthropod section within the invertebrate chapter. Jon Norenburg and Mary Rice of the Smithsonian Institute provided significant input on nemertines and sipunculans, respectively. We thank Bailey Estrada (East Coast Biologists, Inc.) for many hours helping develop the figures and tables in the algae and marine turtle chapters, Larry Wood (Palm Beach Zoo) for sharing his hawksbill turtle research findings, and Mark and Diane Littler (Smithsonian Institute) for permission to reference their functional form tables and concepts. We thank Scott Hurley (Harbor Branch Foundation) and Kirsten Jones (Gumbo Limbo Nature Center) for allowing use of their photographs to better illustrate some nearshore hardbottom habitats. We also thank Stacy Prekel and Jessica Craft of Coastal Planning and Engineering, Inc. for graciously provided data from their monitoring projects. Finally, we thank Lance Jordan (Nova Southeastern University Oceanographic Center) and Grant Gilmore (Estuarine, Coastal, and Ocean Science, Inc.) for reviews and comments on several chapters. Suggested Citation: CSA International, Inc. 2009. Ecological functions of nearshore hardbottom habitat in east Florida: A literature synthesis. Prepared for the Florida Department of Environmental Protection Bureau of Beaches and Coastal Systems, Tallahassee, FL. 186 pp + apps. Acknowledgments Executive Summary Given the complex policy questions involving hardbottom burial and mitigation, the consensus need for ecosystem-based management, and the large but unsynthesized literature base, this study responds to four issues: 1) What are specific ecological functions of nearshore hardbottom (NHB) (0 to 4 m depth)?, 2) What is happening to the coastal ecosystem (broader than NHB) when NHB is lost due to nourishment?, 3) Is offshore hardbottom (OHB) (>6 m depth) able to compensate for the loss of NHB?, and 4) If the NHB habitat has specific properties and functions that cannot be compensated for by existing OHB habitat, what are the best mitigation alternatives for the loss of natural NHB? Very little depth-specific data exist for a majority of taxa throughout the region, which currently limits some of our ability to summarize core functional differences between NHB and OHB. However, a good deal of new information has been assembled and examined on shallow hardbottom structure and distributions (Section 1); the algal, invertebrate, fish, and turtle assemblages associated with shallow hardbottom (Section 2); and primary ecological functions of shallow hardbottom with a focus on latitudinal and depth variations, and implications for improved mitigation planning and implementation (Section 3). ALGAE, INVERTEBRATE, FISH, AND TURTLE ASSEMBLAGES Shallow hardbottom of southeast and east central Florida supports a sometimes diverse reef assemblage consisting of algae, invertebrates, fishes, and sea turtles. The fish and sea turtle components of the assemblage tend to be dominated by juvenile life stages. Patches of NHB exist in portions of Broward, Palm Beach, Martin, St. Lucie, Indian River, and Brevard Counties. Although these areas typically are separated by kilometers of sand, there are some areas where there is a semi-continuous hardbottom gradient from the beach into depths exceeding 6 m. Offshore, many mid-shelf areas are also dominated by expanses of sand, despite the variable occurrence of several mid-shelf reefs. Therefore, in many shallow areas, there are no natural habitats in the same or adjacent nearshore areas that can support equivalent abundances of early life stages of fishes and the invertebrates on which they largely feed. Absences of nursery structure can result in increased predation and lowered growth. In newly settled and juvenile stages, such conditions could foster demographic bottlenecks that ultimately result in lowered local population sizes (Jones, 1991). Algae The total number of recorded algal taxa, both identified and unidentified, is approximately 340, including 277 known species. Potentially dominant genera are Ceramium, Dictyota, Hypnea, Laurencia, Gelidium, Caulerpa, Jania, and Ulva, depending on subregions and other factors. Sunlight converted into macroalgal tissue is directly eaten by as many as 20 genera of invertebrates, at least 14 genera of fishes, and the juvenile stage of the endangered green turtle, Chelonia mydas. Algae are a dominant driver of the food web and also contribute to shelter used by hundreds of species of invertebrates and fishes. All algal species contribute to oxygen and nutrient production. In terms of functional form groups, jointed-calcareous algae are most responsible for sediment enrichment and sand building. The abundance and diversity of macroalgae on NHB vary substantially with changes in latitude from Cape Canaveral to Miami Beach. Invertebrates Over 533 species of invertebrates have been identified along the east Florida coast, and there are likely to be more. The diversity of sessile species is greatest for cnidarians (~21%), bryozoans (~29%), and sponges (~19%). Some sessile groups may not be represented with such high diversity but can occur in very high biomass. A primary example is the sabellariid polychaete Phragmatopoma lapidosa, which can Executive Summary ES-1 be very abundant along the mid- to north sections of the project area and is a habitat engineer that creates structure supporting high diversities of many other invertebrates. The most diverse and generally abundant motile invertebrates are arthropods and polychaetes, which represent 47% and 28%, respectively, of the total number of motile invertebrate species. Over 100 species of crustaceans are extremely abundant, especially on worm reef-dominated hardbottoms. These include crabs, stomatopods, shrimp, isopods, and amphipods. There are over 87 reported polychaete species that are likely to be very abundant, although more research is needed to confirm this. There are also fairly high numbers of gastropods, flat worms, ribbon worms, and echinoderms on these habitats. Primary ecological functional roles of invertebrates along the east Florida coast include 1) shelter-enhancing organisms that increase local diversity of fishes and invertebrates, and 2) predators or prey in local food webs. Generally, the highest community biomasses along the mainland east Florida coast occur in hardbottom areas with higher abundances of sessile invertebrate species (some may be considered foundational or keystone contributors to the community) that enhance local shelter. Along the Florida coast, important shelter-enhancing taxonomic groups are hard and soft corals, sponges, tunicates, molluscs, barnacles, and polychaetes (i.e., P. lapidosa). However,