A group of scientists from Canada and Australia have discovered that the overfishing of sharks leads to a decrease in coral reef health. With fewer sharks present in the reef ecosystem, the food chain in the reefs changes. The number of smaller predators increases, which leads to a decrease in the number of herbivorous fish that the smaller predators eat. The herbivorous fish are responsible for eating algae that grows on reefs. Without the fish to keep the algae in check, young corals trying to grow are overwhelmed. This cycle is especially damaging when reefs are recovering from natural disturbances such as cyclones, which are becoming more frequent because of climate change.
The study offers a new angle for protecting the world’s delicate reefs. Reef sharks often remain within small territories associated with a single reef. The formation of new marine-protected areas around the sharks’ territories could prevent overfishing and keep the delicate balance that allows reefs to recover from damage and disruptions.
The research will be published in the September 28 issue of the journal PLOS One. Lead author Jonathan Ruppert recently completed his PhD at U of T. Marie-Josée Fortin of U of T’s Department of Ecology and Evolutionary Biology was also part of the team.
