SANTA CRUZ, CA--A study of the tropical coral reef system along the coastline of Kenya has found dramatic effects of overfishing that could threaten the long-term health of the reefs. Led by scientists at the University of California, Santa Cruz, the study was published in the journal Coral Reefs (online publication January 28).
The researchers found that the loss of predatory fish leads to a cascade of effects throughout the reef ecosystem, starting with an explosion in sea urchin populations. Excessive grazing by sea urchins damages the reef structure and reduces the extent of a poorly studied but crucially important component of the reefs known as crustose coralline algae. Coralline algae deposit calcium carbonate in their cell walls and form a hard crust on the substrates where they grow, helping to build and stabilize reefs. They also play a crucial role in the life cycle of corals.
"Some coralline algae produce a chemical that induces coral settlement, in which the larval stage in the water settles on the ocean floor to grow into an adult. This settlement must happen for reefs to recover after disturbance," said lead author Jennifer O'Leary, a research associate with the Institute of Marine Sciences at UC Santa Cruz.
The ability of coralline algae to induce the settlement of coral larvae has been well studied in the laboratory, but few studies have been done to investigate this relationship in the field. O'Leary set out to study the role of coralline algae in reef ecosystems as a UCSC graduate student working with Donald Potts, professor of ecology and evolutionary biology and a coauthor of the paper.
In Kenya, O'Leary teamed up with Tim McClanahan, a UCSC alumnus who now heads the Wildlife Conservation Society's marine programs in Kenya. The researchers compared the types of coralline algae and the number of juvenile corals on Kenyan reefs under three different management conditions: closed, gear-restrict
|Contact: Tim Stephens|
University of California - Santa Cruz