Publisher :
Place of publication :
Publication year : 2009
Thematic : Coral Reef
Language : English
Note
Reports of coral diseases are increasing and may result from human land use and climate
change conditions such as increased water temperature, coral bleaching, runoff from
land, and changes in the ecology of heavily fished reefs. We examined a stable coral
syndrome or a growth anomaly [Porite growth anomaly (PGA)] (skeletal tissue anomaly,
hyperplasia, or ‘tumor’) that was present in 0–15% of massive Porites colonies in 12
Kenyan reef lagoons. At the level of the calice morphology, this growth anomaly showed
larger calices with less distance between calices and some calices with higher than
normal numbers of septa, which indicate the influence of microboring organisms.
Scanning electron micrographs of affected corals revealed a high abundance of fungal
hyphae, a potential microboring pathogenic agent. To test the hypothesis that the PGA
covaries with environmental variables, we evaluated its prevalence in relationship to 16
parameters of water quality, temperature, intensity of bleaching, benthic composition,
and management at the end of the 2005 warm season. Stepwise regression models found
eight environmental variables significantly associated with the frequency of the PGA,
and the site’s bleaching intensity was the most strongly associated variable. When
bleaching intensity was removed from the dataset, the concentration of phosphorus
was the one significant and positively associated variable, which suggest that the other
significant environmental variables were associated with bleaching and not the growth
anomalies. Our hypothetical model of causation is that the patchy loss of symbionts,
often associated with bleaching, reduces calcification, increases susceptibility to pathogens,
and allows endolithic fungi to perforate the skeleton creating a porous and
anomalous growth of the skeleton. Consequently, we suggest that the frequency of
skeletal growth anomalies is expected to increase with the frequency of coral bleaching.
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Keywords : Gatekeepers
Encoded by : Pauline Carmel Joy Eje
