Flower Garden Banks National Marine Sanctuary

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Chapter 3. SITE DESCRIPTION

Flora

Brief description of the main plant assemblages significant or particular in the area:


All plant species at the Flower Garden Banks are marine. More than 100 species of green, brown and red algae have been identified at the Flower Garden Banks.


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These include many of the typical tropical marine species found on coral reefs in the Caribbean that form a complex of erect and turf growth forms. Algae growth and species distribution is ecologically linked to the amount of nonliving-coral hard substrate, nutrient inputs (low at the Flower Garden Banks) and grazing intensity. In addition, corals themselves are a consortium of plant and animal life. Coral growth and nutrition is closely dependent on their internal symbiotic algae. In deeper areas of the sanctuary (45 - 85 m), coralline algae is important in benthic habitat formation and builds nodules up to 25 cm in diameter, pavements and crusts.

List of plant species within the site that are in SPAW Annex I

List of species in SPAW annex I Estimate of population size Comments if any

List of plant species within the site that are in SPAW Annex III

List of species in SPAW annex III Estimate of population size Comments if any

List of plant species within the site that are in the IUCN Red List. UICN red list : http://www.iucnredlist.org/apps/redlist/search You will specify the IUCN Status (CR:critically endangered; EN:endangered; VU:vulnerable).

List of species in IUCN red list that are present in your site IUCN Status Estimate of population size Comments if any

List of plant species within the site that are in the national list of protected species

List of species in the national list of protected species that are present in your site Estimate of population size Comments if any

Fauna

Brief descript° of the main fauna populations and/or those of particular importance present (resident or migratory) in the area:


The habitats of the Flower Garden Banks have been classified into depth related zones that contain distinctive communities of fauna and associated flora.

Coral Reef Zone
The coral reef zone is the shallowest zone at the Flower Garden Banks, occurring at depths of between approximately 17 to 44 meters. Large, closely spaced star and brain coral heads, many greater than 3 meters in diameter and height dominate the zone. Reef topography is relatively rough, with many vertical and inclined surfaces and crevices. Between groups of coral heads, there are numerous sand patches and channels. This zone is characterized by a high diversity coral assemblage dominated by Montastraea spp., Diploria strigosa, Colpophyllia natans and Porites astreoides. Coralline algae, and filamentous and leafy algae also occur on reef substrates, but are not dominant members of the benthic assemblage. Madracis mirabilis forms large monotypic stands in deeper portions of the coral reef community. Sponges and Agaricia spp. are common in crevices and cavities of the reef.

Coral Community Zone
The coral community zone is comprised of areas that, while not considered to be “true” coral reefs, do contain hermatypic (reef-building) coral species at low densities, or are characterized by other coral reef associated organisms, such as the hydrozoan Millepora spp. (fire coral), sponges and macroalgae. Coral communities are found in depth ranges similar to those that contain coral reefs (17 to 50 meters), where other environmental factors do not allow full development of coral reefs. This community type is predominant at Stetson Bank. The coral community at the Flower Garden Banks is characterized by the blushing star coral, (Stephanocoenia intersepta), the great star coral, (Montastraea cavernosa), and the large grooved brain coral, (Colpophyllia natans), and occurs between depths of 40 to 55 meters. Lettuce corals (Agaricia spp.) and brain coral (Diploria strigosa) are also an important part of the community. Crustose coralline algae are found on dead coral rock, along with leafy algae and numerous sponges. The dominance of hard corals declines with depth, and few coral colonies occur between 45 to 50 meters at East and West Flower Garden Banks. Coral communities at Stetson Bank are dominated by a Millepora-sponge assemblage, along with areas of Madracis decactis and individual colonies of Diploria strigosa and several other coral species.

Coralline Algae Zone
Found in depths between 45 to 90 m, the coralline algae zone is made up of algal nodule fields, pavements and coralline algal reefs. Coralline algae occurs within the photic zone above approximately 85 meters. This zone is rich in sponges, algae, gorgonians, and black coral, and harbors healthy populations of deep reef fish including rough tongue bass (Pronotogrammus martinicensis), scamp (Mycteroperca phenax), and marbled grouper (Dermatolepis inermis). Crustose coralline algae forms large beds of algal nodules (also called “rhodoliths”), or massive reef structures composed of large plates and ridges. A variety of sponge species are abundant in this zone, along with numerous antipatharians (black corals) and octocorals (sea whips). Few reef-building corals occur at these depths, and are primarily limited to small isolated colonies.

Deep Coral Zone
Found in depths typically below 90 meters, the deep coral zone is dominated by eroded reef outcroppings, azooxanthellate (non-reef building) solitary hard corals, antipatharian and gorgonian corals, deep reef fish, sponges, bryozoans, and crinoids (feather stars). Rock surfaces are often highly eroded, and lack coralline algal growth. The deep coral zone is sometimes characterized by turbid water conditions, and reef outcrops may often be covered with a thin layer of silt (particularly at Stetson Bank).

Soft Bottom Community Zone
Large expanses of mud, sand, and silt substrates, which typify the soft bottom community zone, are found in the deepest parts of the banks and surrounding the banks. Features of the soft bottom community include pits, burrows, Cirrhipathes (Stichopathes) fields, stalked anemones, and echinoderms. Squat lobster (Munida sp.) are often observed in this zone. Deeper areas of the sanctuary are characterized by a soft, level bottom composed of both terrigenous sediments originating from coastal rivers and carbonate sediments resulting from calcareous planktonic remains and erosion of adjacent rocky outcrops and coral reefs. Soft bottom communities are often characterized by sand waves, burrows and mounds.
Transitional zones between soft bottom communities and hard bottom features are characterized by exposed rubble, isolated patch reefs or exposed hard bottom. Areas with buried or exposed carbonate rubble are often colonized by antipatharians, octocorals, or solitary hard corals. These soft bottom communities are important feeding areas for fishes.

Fish
At least 280 species of fish have been documented within the sanctuary, including parrotfish, wrasse, angelfish, boxfish, smooth trunkfish and squirrelfish. Large schools of barracuda (Sphyraena barracuda) and pelagic jacks (Caranx spp.) also occur. Winter brings enormous schools of mackerel (Scomberomorus sp.). The conspicuous deeper water fish in the sanctuary include rough tongue bass, threadnose bass, vermillion snapper, red snapper, scamp, and marbled grouper. Commercially targeted species include snapper, grouper, jacks, and mackerel. Smooth trunkfish (Lactophrys triqueter) are common throughout the Caribbean, but the golden morph of the species is very rare and was first described at the Flower Garden Banks, and has since been rumored to occur in just one other place in the Caribbean.

Sea Turtles
Loggerhead and hawksbill sea turtles reside at all three banks of the sanctuary throughout the year. Loggerheads (Caretta caretta) are most often seen at night or in the late afternoon resting underneath ledges or coral heads. In the early morning they often leave the reef to feed in deeper areas of the sanctuary. The most frequently observed loggerheads are juveniles approaching maturity, perhaps suggesting that the sanctuary reefs serve as a temporary residence for these animals while they prepare to move on to adult feeding areas. Adult female loggerheads have also been sighted on several occasions. Because hawksbill sea turtles (Eretmochelys imbricata) are primarily sponge-eaters, Stetson Bank offers an abundant food source and is likely an excellent habitat for these turtles. A young hawksbill sea turtle has been a resident of Stetson Bank since 1999. A small number of transient hawksbills have also been reported at both the Flower Garden Banks and Stetson Bank.

Sharks & Rays
Approximately 20 species of sharks and rays have been documented at the Flower Garden and Stetson Banks, some seasonal, others year-round. During the winter months, schooling scalloped hammerhead sharks (Sphyrna lewini) and spotted eagle rays (Aetobatus narinari) are visitors to all three banks. The reason for the seasonality of their visits is unclear, but the occurrence is quite predictable. Other winter visitors include occasional sandbar (Carcharhinus plumbeus) and tiger sharks (Galeocerdo cuvier), as well as spinner sharks (Carcharhinus brevipinna), which are often seen leaping out of the water. Summer months usually bring whale sharks (Rhincodon typus) to the area. Nurse sharks are sometimes seen resting under ledges or in crevices in the coral, while large schools of silky sharks (Carcharhinus falciformis) are known to aggregate around oil and gas platforms in the vicinity of the sanctuary during the winter months. Silky sharks have recently been observed
in large schools, exhibiting mating behavior at Stetson Bank. Manta rays (Manta birostris) and the very similar-looking mobula rays (Mobula spp.) are regular visitors to the sanctuary (Figure 11). At least 58 different individuals have been documented and identified by distinctive markings on their undersides. Acoustic tracking of the manta rays has revealed that the mantas are moving between at least the three banks of the sanctuary.

List of animal species within the site that are in SPAW Annex II

List of species in SPAW annex II Estimate of population size Comments if any
Reptiles: Caretta caretta not given
Reptiles: Eretmochelys imbricata not given
Birds: Falco peregrinus not given
Mammals: Mesoplodon europeaus not given
Mammals: Mesoplodon densirostris not given
Mammals: Mesoplodon mirus not given
Mammals: Mesoplodon bidens not given
Mammals: Stenella attenuata not given
Mammals: Stenella frontalis not given
Mammals: Tursiops truncatus not given

List of animal species within the site that are in SPAW Annex III

List of species in SPAW annex III Estimate of population size Comments if any
Hydrozoa: Milleporidae not given Millepora alcicornis
Anthozoa : Antipatharia not given Acanthopathes thyoides Antipathes atlantica Antipathes furcata Antipathes sp. Aphanipathes pedata Elatopathes abietina Phanopathes expansa Plumapathes pennacea Stichopathes sp. Tanacetipathes sp. Plus 11 unidentified species
Anthozoa : Gorgonacea not given Many present. List not compiled.
Anthozoa : Scleractinia not given elkhorn coral Acropora palmata lettuce coral Agaricia agaricites fragile saucer coral Agaricia fragilis ornate cup coral Coenocyathus sp. Colpophyllia amaranthus boulder brain coral Colpophyllia natans knobby brain coral Diploria clivosa symmetrical brain coral Diploria strigosa Eusmilia sp. hat or sunray lettuce coral Helioseris cucullata pointed pencil coral Madracis asperula ten-ray star coral Madracis decactis eight-ray finger coral Madracis cf. formosa yellow pencil coral Madracis auretenra (mirabilis) Madrepora carolina lobed star coral Montastraea annularis great star coral Montastraea cavernosa boulder star coral Montastraea franksi mountainous star coral Montastraea faveolata spiny flower coral Mussa angulosa diffuse ivory coral Oculina diffusa delicate ivory bush coral Oculina tenella Oxysmilia sp. papillose cup coral Paracyathus pulchellus Polycyathus senegalensis mustard hill coral Porites astreoides finger coral Porites furcata finger coral Porites porites speckled cup coral Rhizosmilia maculata artichoke coral Scolymia cubensis Siderastrea bournoni massive starlet coral Siderastrea siderea Stephanocoenia michelini blushing star coral Stephanocoenia intersepta orange cup coral (invasive) Tubastraea coccinea
Molluscs: Strombus gigas not given
Crustaceans: Panulirus argus not given

List of animal species within the site that are in the IUCN Red List. IUCN Red List : http://www.iucnredlist.org/apps/redlist/search You will specify the IUCN Status (CR:critically endangered; EN:endangered; VU:vulnerable).

List of species in IUCN red list that are present in your site IUCN Status Estimate of population size Comments if any
Manta : birostris Unknown not given
Mobula : tarapacana Unknown not given
Mobula : hypostoma Unknown not given
Rhincodon : typus Unknown not given
Mesoplodon : sp. Unknown not given
Stenella : frontalis Unknown not given
Tursiops : truncatus Unknown not given
Caretta : caretta Unknown not given
Eretmochelys : imbricata Unknown not given

List of animal species within the site that are in the national list of protected species

List of species in the national list of protected species that are present in your site Estimate of population size Comments if any