HR: 16:30h
AN: OS52J-09    [PDF]
TI: Distribution and Biozonation of Anthozoa Along the Southwestern Margin of Little Bahama Bank.
AU: * Messing, C G
EM: messingc@nova.edu
AF: National Coral Reef Institute Nova Southeastern University Oceanographic Center, 8000 N. Ocean Drive, Dania Beach, FL 33004 United States
AU: Moyer, R P
EM: moyerr@nova.edu
AF: National Coral Reef Institute Nova Southeastern University Oceanographic Center, 8000 N. Ocean Drive, Dania Beach, FL 33004 United States
AU: Walker, B K
AF: National Coral Reef Institute Nova Southeastern University Oceanographic Center, 8000 N. Ocean Drive, Dania Beach, FL 33004 United States
AU: Dodge, R E
EM: dodge@nova.edu
AF: National Coral Reef Institute Nova Southeastern University Oceanographic Center, 8000 N. Ocean Drive, Dania Beach, FL 33004 United States
AB: Little Bahama Bank (LBB) is the northernmost of a series of tectonically stable carbonate platforms that lies along the subsiding continental margin of southeastern North America. Data derive from seven parallel, downslope video transects taken via ROV and spanning 2000 m just west of the channel entrance to Freeport Harbor, Grand Bahama I., on the southwestern bank margin. These were supplemented by four cross-slope quantitative photo transects. Below a narrow bank-margin reef in $\sim52-69 m$, the deep forereef consists of an irregular, low-relief, sediment-veneered hardbottom slope of usually $40-60\deg$, with locally steeper scarps, rocky outcrops, ledges, apparently loose talus ranging from small rubble to large rocks, and rare larger reentrant caves roofed by overhanging ledges. Slope angle generally decreases with increasing depth, and sediment deposition (both {\it Halimeda} sand and finer grains) increases correspondingly. With the exception of $\sim2-3$ species of green macroalgae above 115 m, octocorals and antipatharians are the most abundant attached macrofaunal organisms at all depths (although sponges account for a greater percentage of bottom cover at one quantitative site). Octocorals are chiefly ellisellids and, especially below 100 m, paramuriceids. Antipatharians are usually the most abundant macroinvertebrates on hard substrates below 120 m. Of these, {\it Stichopathes luekteni} dominates in most areas and may form dense forests in $\sim130-150$ m. The deep forereef ends in 164-190 m, often accompanied by substantial talus. Large solitary corals ({\it Desmophyllum dianthus}) occur uniquely at the deep end of the line where hard substrates penetrate to 190 m. The gentler slope below consists chiefly of unconsolidated sediment. Scattered rubble or outcrops support occasional {\it S. luetkeni}, which may also protrude through the sediment from buried hard substrates. Cnidarians account for 0.82 to 4.55\% of bottom cover at the four quantitative sites (98-146 m). Submersible surveys in deeper water to the northwest reveal large mounds in 325-430 m topped with numerous flabellate scleractinians ({\it Madrepora carolina}), octocorals and crinoids. Elongated lithoherms in 580-700 m may support extensive thickets of {\it Lophelia pertusa}.
DE: 3045 Seafloor morphology and bottom photography
DE: 4804 Benthic processes/benthos
DE: 4815 Ecosystems, structure and dynamics
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting