Microbes, sponges, and wormsthe side effects of pollution and heavy fishingare adding insult to injury in Kenya's imperiled reef systems, according to a recent study by the Wildlife Conservation Society and the University of Azores.
The authors of the study have found that pollution and overfishing on reef systems have an ecological cascading effectthe proliferation of microbes, sponges, and wormsthat further degrade corals, a discovery that underlines the complexity of reefs and possible solutions.
The study appears in the online edition of Marine Ecology Progress Series. The authors include M. Carreiro-Silva of the Center of IMAR of the University of Azores and Tim McClanahan of the Wildlife Conservation Society.
The paper examines how human activities can create unexpected complications in coral reef recovery and management. For instance, recent experimental studies by Carreiro-Silva and colleagues in Belize and Kenya demonstrated that a higher nutrient content in coral reefs associated with growing agriculture activity and urbanization increased the rate at which reefs eroded from microbes such as bacteria, fungi, and algae, as well as larger animals like sponges and worms. While the study cites previous work suggesting a faster erosion of reef calcium carbonate with high pollution levels, the experimental manipulations and use of reefs experiencing different levels of fishing and pollution strongly supports those previous conclusions.
An entirely new finding from this research is that worms are major eroders of reefs where fishing is heavy, while sponges play this same role in unfished reefs of the kind found in marine parks. This suggests that it is not only nutrients and pollution that are eroding the reef substratum. Marine consumers like fish and sea-urchins also appear to be influencing species that erode the reef substratum.
In heavily fished reefs, sea-urchins are the dominant grazers, and
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Wildlife Conservation Society