DEEPEST DISTRIBUTION OF ATLANTIC HERMATYPIC CORALS DISCOVERED IN THE BAHAMAS.

Authors

John K. Reed, Florida Atlantic University

Author Type

Faculty

Document Type

Article

Abstract

Hermatypic corals were collected in deep water with the JOHNSON-SEA -LINK submersibles on the western and southern margins of the Little Bahama Bank (LBB), northern Grand Bahama Bank (GBB), and San Salvador Island, Bahamas. The deepest distribution of hermatypic corals known in the Atlantic Ocean was found at San Salvador. Agaricia grahamae was collected from a firm attachment on the wall at 115m (observed to 119m), and Montastrea cavernosa from 11 3m. When compared with the other collection sites, maximum depth of coral growths was shallowest off western LBB (A. grahamae - 76m, M. cavernosa - 61m, Madracis decactis -75m) and northern GBB (Agaricia sp. - 76m) and was intermediate off southern LBB (M. decactis - 98m, M. cavernosa - 93m, A. grahamae -91m).

The variations in maximum depth distribution of the corals at these sites is probably due to geomorphology of the bank margins, sediment flux, and light penetration. The base of the vertical wall at the shelf edge is approximately 120, 100, 90 and 90m at San Salvador, southern and western LBB, and northern GBB sites, respectively. Below the wall at San Salvador is a steep (60-70*) limestone slope with little sediment accumulation. At the other sites, a rubble slope generally abuts the wall base, preventing deeper coral growth. Flux of shelf sediment onto the deeper reefs at San Salvador, which is a small island with narrow shelf, may be relatively low compared to GBB and LBB sites. Deepest coral growth at San Salvador was greatest on the eastern and southern margins where incident light would be greatest. Maximun photosynthetically active radiation (400 -700 rm) near the maximum depth of coral growth was 2.55 µΕ/m²/s (0.15 % of surface irradiance). Ranges of temperature (22.6-30.0 ' C) and conductivity (51.1 -57 µmho/cm²) were similar at all sites and probably not factors in variations of coral distribution.

Publication Date

1985

Comments

Florida Atlantic University. Harbor Branch Oceanographic Institute contribution 448.

Recommended Citation

This manuscript is an author version with the final publication available and may be cited as: Reed, J. K. (1985). Deepest distribution of Atlantic hermatypic corals discovered in the Bahamas. In C. Gabrie & M. Harmelin (Eds.), Proceedings of the Fifth International Coral Reef Congress. Tahiti, 27 May -1 June 1985. Vol. 6 (pp. 249-254). Moorea, French Polynesia: Antenne Museum-Ephe.