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SL 305

The Importance and Status of Florida Coral Reefs: Questions and Answers1

Cory J. Krediet, Kim Ritchie, and Max Teplitski2

Introduction A: Corals are invertebrate animals that live in marine environments. Most corals are colonial Coral reefs are some of the most productive and animals, with each colony consisting of myriads of diverse ecosystems in the world; however, they are individual polyps, all of the same origin (Figure 1). also some of the most threatened. Here we address a Like some of their relatives (jellyfish and sea number of the most common questions regarding anemones), most corals form mutually beneficial coral reef biology, coral reef health, and the relationships (symbioses) with single-celled ecological and economic benefits coral reefs dinoflagellates and bacteria. The symbiotic provide. dinoflagellates are commonly referred to as “zooxanthellae.” In this relationship, the polyp (an Q: What exactly is a coral? animal) provides a protective environment and nitrogen-containing nutrients to the zooxanthellae that live within the animal cells. In turn, the zooxanthellae fix dissolved CO through 2 photosynthesis to produce carbohydrates that the coral animal can use. Corals assimilate carbohydrates for their own nutritional needs and then excrete the excess onto the coral surface in the form of mucus. Coral mucus mostly consists of carbohydrates and Figure 1. A) An elkhorn coral colony, Acropora palmata. proteins. Mucus can protect the coral from damage Each colony contains thousands of individual polyps caused by ultraviolet (UV) irradiation, drying at low similar to those in (B). Photograph by Cory Krediet (South tides, and harmful bacterial colonization. Corals also Water Caye, Belize); B) An individual polyp of Aiptasia pallida, a model organism for coral studies. The brown use mucus to help remove sediment from their upper color is due to pigments in the zooxanthellae. Photograph surfaces. In addition to carbohydrates that can be by A. Alagely (UF). transferred to the coral by the zooxanthellae, coral

1. This document is SL 305, one of a series of the Soil and Water Science Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date August 2009. Revised May 2010. Visit the EDIS Web Site at http://edis.ifas.ufl.edu. 2. Cory J. Krediet, graduate fellow, Department of Soil and Water Science; Kim Ritchie, staff scientist, Mote Marine Laboratory, courtesy faculty, Department of Soil and Water Science; Max Teplitski, assistant professor, Department of Soil and Water Science; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

The Importance and Status of Florida Coral Reefs: Questions and Answers 2 polyps are capable of capturing food using their many types of fish and lobsters. Mucous slime tentacles (suspension feeding). secreted by corals is high in polysaccharides and proteins. The slime is an important food source for The roles of bacteria in this symbiosis are much some plankton consumed by commercially harvested less clear. They are hypothesized to fix atmospheric fish species. Florida coral reefs provide habitat for nitrogen for their polyp and zooxanthellae partners, more than 6,000 species of marine life and support but they may also produce various antibiotic commercial and recreational fishing industries that compounds that function to protect against infection. generate approximately $60 million annually (NOAA 1995; Bhat 2003). Q: What are coral reefs? In addition to providing food and habitat for A: Corals are found in many parts of the planet, other species, corals—especially soft corals—are but their distribution is limited by environmental being explored for their medicinal properties. conditions (especially light and temperature). Coral Chemicals purified from corals have promising reefs are typically found in shallow waters between anticancer and antibacterial properties. The estimated 30¡north and 30¡south latitudes. However, there value of the planet's coral reef resources is $375 are some non-reef-forming coral species that live in billion a year (Costanza et al. 1997). deep water, and some, like those belonging to the genus Lophelia, thrive in the deep ocean as far north Florida reefs are a major tourist attraction. as Norway. Visitors spend an estimated $460Ð$1,087 on each individual trip to a reef (Park et al. 2002). In Corals can be divided into those that produce southeast Florida, coral reefs contribute at least $4.4 calcium carbonate skeletons ("hard corals") and those billion annually to local economies (based on that build a protein-based skeleton ("soft corals"). expenditures by residents and visitors of Palm Beach, The former group includes the reef-building corals Broward, Miami-Dade and Monroe counties) and and is the type discussed in this publication. The latter directly provide employment for 98,000 people group contains sea fans, sea rods and sea whips. (Johns et al. 2001). Coral reefs are calcium carbonate structures that The “use value,” or maximum amount of are built by some species of hard corals and grow money that reef users are willing to pay to maintain over time. The coral polyps remove dissolved carbon the reefs in their existing condition and to add more dioxide and calcium from the ocean water and artificial reefs to the system in the aforementioned combine the substances to form limestone (calcium Florida counties (from June 2000 to May 2001), was carbonate) that is laid under each polyp to form a estimated to be $8.5 billion (Johns et al. 2001). solid structure. A living, hard coral consists of a thin layer of connected polyps on top of a limestone coral Q: What factors have led to coral reef skeleton. Typically the growth rate of this skeleton is decline worldwide? rather slow (0.5Ð2 cm per year), but favorable conditions can lead to more rapid growth (Edmunds A: Extensive coral mortality can be caused by 2007). catastrophic natural events (storms, hurricanes, volcanic eruptions). Ship groundings, boat anchor Q: Why are coral reefs important to damage, poaching, and damage to corals from economies? recreational diving can have a significant, negative impact on coral reef ecosystems, especially in densely A: According to the United Nations Atlas of the populated coastal areas like Florida (Bellwood et al. Oceans, reefs support the economies of at least 100 2004). Loss of seaweed-eating fish and sea urchins countries by helping to provide food for more than from overharvest and/or disease has resulted in one billion people (UN 2010). While corals are not overgrowth of some reefs by macroalgae (seaweeds). edible themselves, coral reefs provide habitat for The macroalgae can cause coral death by many commercially important species, including overgrowing, shading out or increasing sediment load Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

The Importance and Status of Florida Coral Reefs: Questions and Answers 3 on corals. In many developing nations, sediment Q: What are coral diseases and runoff from land-clearing activities has negatively where do they come from? impacted coral reef health (Mumby and Steneck 2008). A: Beginning in the early 1980s, the proportion of corals within the Florida Keys National Marine Ocean acidification tends to lead to the Sanctuary affected by coral diseases increased dissolution of the calcium carbonate skeleton (which dramatically (Causey 2008). In 1996, 11 species of is not unlike the effects of carbonated beverages on corals were affected; by 1998, 35 species (85% of all our teeth). Since the Industrial Revolution, ocean species) were affected by some type of disease. acidification has increased as evidence by the decreasing pH of the oceans (Fung et al. 2005). This Many organisms that cause coral diseases are not is a concern for reef scientists as coral skeletons are dedicated pathogens but are opportunistic. made from limestone that dissolves when pH is Opportunistic pathogens normally are found in the lowered. Studies are underway to investigate the environment and are generally benign (Rosenberg et effect of changes in pH on corals and coral reefs. al. 2007). Opportunistic pathogens invade their hosts only when the host defense system is compromised. Coral bleaching and coral diseases (discussed Coral diseases caused by opportunistic pathogens are further below) can have devastating impacts on now widespread. corals. Coral diseases—such as black band disease, Q: What is Coral Bleaching? white band disease, and white plague—have resulted in mass mortalities of some coral species, especially A: Coral bleaching is the loss of color resulting in the western Atlantic Ocean. Black band disease from the loss or expulsion of symbiotic zooxanthellae was first reported on brain corals in Bermuda in the or the degradation of the single-celled organisms' early 1970s but became rampant in other species in photosynthetic pigments (Hoegh-Guldberg 1999; the Florida Keys, and elsewhere, in 1985. A group of Dunn et al. 2007). Left without their symbiotic microbial species, including cyanobacteria, causes dinoflagellates, bleached corals appear white (the black band disease. It affects many massive corals color of the calcium carbonate skeleton). Corals will and sea fans; however, it does not seem to affect the feed more with their tentacles when bleached to branching elkhorn and staghorn corals. The cause of compensate for the loss of the photosynthetically white band disease is unknown, but it seems to only driven carbon food source. Coral bleaching generally affect elkhorn and staghorn corals. White plague is a occurs in times of stress, often caused by warm sea bacterial disease that affects massive and plating surface temperature or UV radiation from the sun. corals and now affects about half of the reef-building When environmental conditions become favorable corals in the Caribbean. White plague can kill corals later, the corals may reacquire zooxanthellae and may within days or weeks. White pox, a disease that killed recover. However, many bleached coral colonies will many elkhorn corals in the Florida Keys in the 1990s, not recover and will die. Coral bleaching also can be is caused by a bacterium, Serratia marcescens, which caused by pathogens that produce toxins that can is a common, opportunistic pathogen of animals and either stress or poison photosynthetic pigments in humans. zooxanthellae. First reports of massive coral bleaching associated with elevated sea surface The discovery of Serratia marcescens, which is temperatures in the Florida Keys were in the 1980s, sometimes found in human waste, prompted research although earlier marine perturbations (cold water on the role of human activities in coral reef health. stress, brief periods of warming, reduced light While this observation is important, conclusive penetration) have been recorded for the region evidence that wastewater is reaching and adversely (Causey 2008). affecting coral reef environments along the Florida Keys is limited. However, a recent study demonstrated that S. marcescens isolates from Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

The Importance and Status of Florida Coral Reefs: Questions and Answers 4 diseased coral colonies were identical to isolates from Nutrient enrichment (for example, from the human sewage effulent (Sutherland et al. 2010). runoff of fertilizers used in agriculture, sport turfs, or on private lawns) also directly influences the Q: How do human influences affect dynamics of the coralÐzooxanthellae symbiosis. the health of Florida's coral reefs? Zooxanthellae density increases in response to high concentrations of dissolved inorganic nutrients (e.g., A: Human activities and their direct and indirect nitrogen and phosphorus). Under these conditions, outcomes can impact coral reef ecosystems. Although coral skeleton growth often decreases, but the these ecosystems may recover from natural disasters, mechanism causing this decrease has yet to be their ability to recover from human impacts is less identified. Increased particulate organic matter (e.g., certain. Unlike natural disturbances, such as clay and organic particles suspended in the water) hurricanes, the effects of human activities are often also indirectly influences corals by reducing light sustained, cumulative (Szmant 2002; Lapointe et al. penetration to the zooxanthellae. If prolonged, this 2004), or occur so frequently (e.g. overfishing) that may lead to lower carbon gain by the coral from there is little time for reefs to recover. Frequent and zooxanthellae photosynthesis, slower calcification constant removal of important herbivorous and rates, and thinner coral tissue. Also, as particles settle predatory fish from the reef ecosystem alters the on the coral surface, the coral must put more energy dynamics of the reef. For example, herbivorous fish into mucus production to slough off the sediment. are required to control the growth of macroalgae (which can outcompete corals for space), and Q: What can Floridians do to help predatory fish keep populations of coral-feeding fish maintain health of coral reef at sustainable levels. ecosystems? Global climate change is regarded as one of the ¥ Educate yourself about coral reefs. Learn about major threats to the future of coral reefs because coral reef research carried out by the Florida temperature increases of only a few degrees induce Department of Environmental Protection global-scale coral bleaching episodes and mortality. (http://www.dep.state.fl.us/coastal/habitats/ Warming water is the leading cause of coral reef coral.htm), Florida universities, and decline, and it may increase outbreaks of marine not-for-profit research organizations disease. If trends continue, atmospheric carbon (http://www.mote.org, dioxide concentration will continue to increase, and http://www.flaquarium.org, and the pH of ocean waters will continue to decrease. http://floridakeys.noaa.gov/eco_discovery.html). These changes will increase stress to corals and increase their susceptibility to bleaching and ¥ When diving, snorkeling, and boating around disease. coral reefs, it is important not to damage the corals by touching them, standing on them, or Through human activities, corals are exposed to using them for anchoring. increasing nutrient, sediment, and pollutant loads discharged from the land that alter the dynamics of ¥ Do not participate in illegal trade or harvest of the reef ecosystem. Seaweed and cyanobacterial corals. blooms result from nutrient enrichment of otherwise nutrient-poor waters. These blooms outgrow ¥ Help reduce nutrient runoff: Contact your local seagrasses and adult corals and inhibit recruitment of Extension office (locations at juvenile corals. Corals may also be outcompeted by www.solutionsforyourlife.com) to learn other filter feeders (e.g., sponges, bivalves, ascidians, Florida-Friendly Landscaping principles. bryozoans, and barnacles) that are more efficient at utilizing particulate organic matter. ¥ These simple steps can help us contribute to the preservation of our unique coral reef ecosystems. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

The Importance and Status of Florida Coral Reefs: Questions and Answers 5

Acknowledgements Mar Freshwater Res 50:839-866.

Preparation of this publication was supported by Johns, G. M., V. R. Leeworthy, F. W. Bell, M. A. grants to the coauthors from the Mote Marine Bonn, F. S. U. a. N. in association with Hazen and Laboratory Protect Our Reefs Grants Program, which Sawyer Environmental Engineers and Scientists, and is funded by proceeds from the sale of the Protect Our G. P. Yang. 2001. Socioeconomic study of reefs in Reefs specialty license plate southeast Florida. Page 348 in P. B. C. Broward (http://www.mote.org/4reef). County, Miami-Dade County, Monroe County, Florida Fish and Wildlife Conservation Commission, References and Suggested Further National Oceanic and Atmospheric Administration, Reading editor. Hazen and Sawyer, PC.

Bellwood, D. R., T. P. Hughes, C. Folke, and M. Krediet, C. J., K. B. Ritchie, M. Cohen, E. K. Lipp, Nystrom. 2004. Confronting the coral reef crisis. K. P. Sutherland, and M. Teplitski. 2009. Utilization Nature 429:827-833. of mucus from the coral Acropora palmata by the pathogen Serratia marcescens and by environmental Bhat, M. G. 2003. Application of non-market and coral commensal bacteria. Appl Environ valuation to the Florida Keys marine reserve Microbiol 75:3851-3858. management. J Environ Management 67:315-325. Lapointe, B. E., P. J. Barile, and W. R. Matzie. 2004. Causey, B. D. 2008. Coral Reefs of the U.S. Anthropogenic nutrient enrichment of seagrass and Caribbean. Pages 61-72 in C. Wilkinson and D. coral reef communities in the Lower Florida Keys: Souter, editors. Status of Caribbean coral reefs after discrimination of local versus regional nitrogen bleaching and hurricanes in 2005. Global Coral Reef sources. J Exp Mar Biol Ecol 308:23-58. Monitoring Network, and Reef and Rainforest Research Centre, Townsville. Mumby, P. J. and R. S. Steneck. 2008. Coral reef management and conservation in light of rapidly Costanza, R., R. dArge, R. deGroot, S. Farber, M. evolving ecological paradigms. Trends Ecol Evol Grasso, B. Hannon, K. Limburg, S. Naeem, R. V. 23:555-563. ONeill, J. Paruelo, R. G. Raskin, P. Sutton, and M. vandenBelt. 1997. The value of the world's NOAA. 1995. Florida Keys National Marine ecosystem services and natural capital. Nature Sanctuary Draft management plan/environmental 387:253-260. impact statement.

Dunn, S. R., C. E. Schnitzler, and V. M. Weis. 2007. Park, T., J. M. Bowker, and V. R. Leeworthy. 2002. Apoptosis and autophagy as mechanisms of Valuing snorkeling visits to the Florida Keys with dinoflagellate symbiont release during cnidarian stated and revealed preference models. J Environ bleaching: every which way you lose. P Roy Soc Management 65:301-312. B-Biol Sci 274:3079-3085. Rosenberg, E., O. Koren, L. Reshef, R. Efrony, and I. Edmunds, P. J. 2007. Evidence for a decadal-scale Zilber-Rosenberg. 2007. The role of microorganisms decline in the growth rates of juvenile scleractinian in coral health, disease and evolution. Nat Rev corals. Mar Ecol-Prog Ser 341:1-13. Microbiol 5:355-362.

Fung, I. Y., S. C. Doney, K. Lindsay, and J. John. Sutherland, K. P., J. W. Porter, J. W. Turner, B. J. 2005. Evolution of carbon sinks in a changing Thomas, E. E. Looney, T. P. Luna, M. K. Meyers, J. climate. Proc Natl Acad Sci U S A C. Futch, and E. K. Lipp. 2010. Human sewage 102:11201-11206. identified as likely source of white pox disease of the threatened Caribbean elkhorn coral, Acropora Hoegh-Guldberg, O. 1999. Climate change, coral palmata. Environ Microbiol 12:1121-1131. bleaching and the future of the world's coral reefs. Archival copy: for current recommendations see http://edis.ifas.ufl.edu or your local extension office.

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Szmant, A. 2002. Nutrient enrichment on coral reefs: Is it a major cause of coral reef decline? Estuar Coast 25:743-766.

Teplitski, M. and K. Ritchie. 2009. How feasible is the biological control of coral diseases? Trends Ecol Evol 24:378-385.

UN. 2010. UN Atlas of the Oceans. http://www.oceansatlas.org/index.jsp.