Editing Biscayne National Park (section)

===Coral reef and offshore waters===
[[File:Green Sea Turtle Biscayne.jpg|thumb|alt=Sea turtle coming ashore|Green sea turtle]]
Beyond the keys in the Atlantic Ocean the seafloor slopes gradually down before rising in an almost continuous coral reef. The reef, composed of living [[coral]]s, is inhabited by more than 200 species of fish, as well as molluscs, crustaceans and worms.<ref name=npsbisc20/> Every coral species in park waters is considered protected by either federal or state regulations.<ref name=npca15>NPCA, p. 15</ref> Coral reefs are estimated to cover about half the area of the park, with about 4000 individual patch reefs and areas of bank-barrier reef.<ref name=npca18>NPCA, p. 18</ref> Hundreds of species of hard and soft corals, [[sea anemone]]s and [[sponge]]s are found in bay and offshore waters.<ref name=npsbisc203>{{cite web|title=Other Invertebrates (corals, sponges, worms, etc.)|url=http://www.nps.gov/bisc/naturescience/otherinvertebrates.htm|work=Biscayne National Park|publisher=National Park Service|access-date=14 March 2013}}</ref> The coral reefs may themselves be subdivided into the outer reef on the edge of the Florida carbonate platform, the patch reefs between the outer reef and the keys, and the reefs in the shoals on either side of the keys. The offshore reefs are dominated by [[elkhorn coral]] to {{convert|10|m|ft|adj=on|sp=us}} water depth, and [[staghorn coral]] below 10 meters. The landward patch reefs are principally composed of [[Montastraea annularis|boulder star coral]] and [[Diploria strigosa|symmetrical brain coral]]. The island shoal reefs mainly consist of [[Siderastrea radians|lesser starlet coral]] and ''[[Porites]]'' finger corals.<ref>Harris, Tuttle, Tuttle, pp. 272–273</ref>

Reef environments in Biscayne National Park have seen declines in species richness and diversity across all fish species from 1977 to 1981 to 2006–2007.<ref name=kellison1>{{cite journal|last=Kellison|first=G.T.|author2=McDonough, V.|author3=Harper, D.E.|author4=Tilmant, J.T.|title=Coral Reef Fish Assemblage Shifts and Declines in Biscayne National Park, Florida, USA|journal=Bulletin of Marine Science|date=January 2012|volume=88|issue=1|page=1|doi=10.5343/bms.2011.1027}}</ref> A sampling program showed declines at all sampling sites. A correlation has been posited between the observed decline in coral reef coverage throughout the Florida Reef tract and the decline in fish species. Declines in populations were noted in both gamefish and in fish species not exposed to fishing pressure. [[algae|Algal]] cover has increased as coral has declined, so coral-dwelling species have decreased while herbivorous fish have increased. Increased overall salinity and changing salinity gradients in Biscayne Bay may also play a role, while [[polychlorinated biphenyl]] and mercury contamination have been noted in fish samples.<ref name=kellison2>Kellison ''et al.'', pp. 19–21</ref>

The park's eastern boundary lies just beyond the rise of the offshore reef at ten-fathom ({{convert|60|ft|m|adj=on|disp=semicolon}}) sea depth. Areas farther offshore are protected within the Florida Keys National Marine Sanctuary, which extends eastward to a boundary corresponding to a depth of {{convert|300|fathom|ft m}}.<ref name=fknms1>{{cite web|title=Florida Keys National Marine Sanctuary and Protection Act|url=http://floridakeys.noaa.gov/about/fknmsp_act.html|publisher=Florida Keys National Marine Sanctuary|access-date=13 February 2013}}</ref> The offshore waters harbor brown pelicans, [[magnificent frigatebird]]s, [[brown booby|brown boobies]], particularly around the offshore lights, and pelagic birds such as [[shearwater]]s and [[petrel]]s.<ref name=npsbisc28/> [[Whale]]s in offshore waters are rare, but can include [[North Atlantic right whale|right whales]], [[humpback whale]]s, [[sperm whale]]s, [[fin whale]]s and [[sei whale]]s, all of them endangered.<ref name=npsbisc22/> The [[smalltooth sawfish]] is similarly rare in park waters and endangered.<ref name=npsbisc31/> Threatened coral species include elkhorn and staghorn corals, as well as [[pillar coral]], listed as endangered in Florida.<ref name=npsbisc22/>