Discovery Bay, Jamaica

Abstract

Mesophotic coral ecosystems occur on fore-reef slopes (~25 to 55 m) and near-vertical deep fore reefs (~55 to ~122 m) off the north Jamaican coast. In the 1960s, T.F. Goreau and colleagues found corals and calcareous green algae (Halimeda) thriving to depths of ~70 m and coralline sponges even deeper. Boring sponges and calcar-eous algae produced prodigious quantities of carbonate muds and sands, some becoming lithified into reef rock and the remainder draining into deeper water. Low-light flattening of corals facilitated sediment shedding and stabilized dislodged colonies. Huge pinnacle reefs with frame work-building Orbicella dominated the upper fore-reef slope (~25 to 45 m) at Discovery Bay. Foliaceous agarici-ids monopolized some lower slopes and the upper deep fore-reef. Submersible-based explorations of the deep fore-reef cliff in 1972 confirmed active framework construction by corals at ~55 to 70 m and by coralline sponges and crustose coralline algae at ~70 to 105 m. Species of deep reef fishes occurred below ~60 to 90 m. The base of the cliff at ~91 to 145 m consisted of lithified sediments and debris. Non-coralline sponges and algae were the dominant benthos from 53 to 120 m in a 1984 submersible study. Fore-reef slope corals have declined greatly since the 1980s, and their skeletons are largely overgrown with algae. Contributing factors include enhanced herbivore losses from overharvesting (fish) or disease (Diadema), repeated bleaching-mortality events, increased trapping of sediments, degraded water quality, hurricanes, and coral diseases. Apart from identified sponges collected with open circuit trimix scuba in the 1990s, the post-1984 condition of the deep fore reef is unknown. Keywords Mesophotic coral ecosystems · Discovery Bay · Jamaica · Fore-reef slope · Deep fore reef 6.