Recovery probabilities of coral reef communities after Acanthaster planci infestation: a case study at Shabror umm gam'ar, Hurghada, Red Sea, Egypt.

Abstract

Recovery patterns of coral reef benthic communities were estimated by linear extrapolation after Acanthaster planci outbreak of 1998 at Shabror Umm Gam'ar, Hurghada of the Egyptian Red Sea. The significance of using linear extrapolation was tested in a range of ten sites by comparison with the actual average yearly recovery rates. A total of 15 permanent transects, each is 10m long, were monitored at 10m and 12m depths in both Shabror Umm Gam’ar and the ten selected sites. The recovery rate estimated by linear extrapolation did not significantly differ from the recovery rate of stony corals in the ten selected sites. Moreover, an error of +7.69% to +17.5% increase in the extrapolated recovery rate exists and should be considered while handling the extrapolated recovery patterns of coral reef benthic communities. Stony corals were characterized by having an extrapolated slow recovery time of 64.9 years in spite of the fast recovery rate (0.67 % over/year) and this is virtually due to the large cover required for restoration as a result of the large devastation by Acanthaster planci. In contrast, soft corals were characterized by having both fast recovery time (RT) and recovery rate (RR) as they are not preferred preys by the COTs. The correlation coefficient is negative between recovery time (RT) and recovery rate (RR), strong between RT and cover required for complete recovery CR, and weak between CR and RR. Diversity had an estimated fast recovery time (RT) of 4.3 years indicating that, the space cleared by Acanthaster planci improves the diversity faster than improving the percent cover.