Accretion patterns in Holocene tropical coral reefs: do massive coral reefs in deeper water with slowly growing corals accrete faster than shallower branched coral reefs with rapidly growing corals?

摘要

It is a widely held concept that tropical coral reefs in shallower water with branched acroporid corals should accrete faster than those in deeper water dominated by massive corals. Results from a study of Holocene development of the largest Atlantic reef system, including paleo-waterdepth data, challenge these concepts. In Belize barrier and atoll reefs, reef accretion-rates range from 0.46 to 7.50 m/kyr, and average 3.03 m/kyr, as measured along 33 dated reef sections. Interestingly, accretion-rates increase with increasing paleo-waterdepth, and sections dominated by massive corals accumulated even slightly faster than those with branched acroporids. Published data from some other reef locations reveal no significant trends when plotting reef accretion-rate versus paleo-waterdepth, also indicating that the above-mentioned concepts should be questioned. Massive corals apparently are more resistant and accrete in lower disturbance conditions in slightly deeper water (5-10 m) and higher accomodation (space available for sediment deposition) as compared to shallow water (0-5 m) branched acroporids, which repeatedly get broken and leveled out during tropical cyclones.