Changes in a coral population on reefs of the northern Florida Keys following a coral disease epizootic

摘要

Populations of the coral Dichocoenia stokesi were quantitatively monitored on reefs of the middle and northern Florida Keys during and after a 1995 epizootic of the coral disease white plague type Ⅱ. Three large-scale surveys were conducted in the falls of 1995, 1998, and 2002 at selected sites throughout the Florida Keys totaling 8478, 6280, and 8792 m~2 respectively. Between 1995 and 2002, the average number of D. stokesi colonies per 314 m~2 site decreased from 44.3 to 11.2, a decline of almost 75%. We found no evidence of coral recruitment in the 7 yr following the epizootic, and have found a continuing pattern of coral population decline. The colony size-frequency distribution pattern on these reefs changed over this time period as well, with the D. stokesi population exhibiting a trend to domination by large colonies, suggesting that the remaining population, while growing, is no longer reproducing. The shift in population to dominance by large colonies is typical of coral populations on degraded reefs. Here we report the results of a quantitative field study on the Florida reefs and compare these data with a similar study on reefs of Lee Stocking Island, Bahamas, that have not experienced a white plague type Ⅱ epizootic.