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Indirect effects of algae on coral: algae‐mediated, microbe‐induced coral mortality
Author(s) -
Smith Jennifer E.,
Shaw Morrigan,
Edwards Rob A.,
Obura David,
Pantos Olga,
Sala Enric,
Sandin Stuart A.,
Smriga Steven,
Hatay Mark,
Rohwer Forest L.
Publication year - 2006
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/j.1461-0248.2006.00937.x
Subject(s) - coral , algae , biology , coral reef , reef , ecology , coral bleaching , aquaculture of coral
Declines in coral cover are generally associated with increases in the abundance of fleshy algae. In many cases, it remains unclear whether algae are responsible, directly or indirectly, for coral death or whether they simply settle on dead coral surfaces. Here, we show that algae can indirectly cause coral mortality by enhancing microbial activity via the release of dissolved compounds. When coral and algae were placed in chambers together but separated by a 0.02 μ m filter, corals suffered 100% mortality. With the addition of the broad‐spectrum antibiotic ampicillin, mortality was completely prevented. Physiological measurements showed complementary patterns of increasing coral stress with proximity to algae. Our results suggest that as human impacts increase and algae become more abundant on reefs a positive feedback loop may be created whereby compounds released by algae enhance microbial activity on live coral surfaces causing mortality of corals and further algal growth.