The overfishing of sharks is harming the world's coral reefs, Australian and Canadian scientists say.
The researchers monitored reefs 300km off Australia's northwest coast, where Indonesian fishers target sharks.
They concluded that wherever shark numbers were reduced due to commercial fishing, there was also a decrease in herbivorous fish, which played an important role in promoting healthy reefs.
Team leader Mark Meekan, from the Australian Institute of Marine Science (AIMS), said there were more mid-level predators such as snappers and fewer herbivores such as parrotfish, which are their prey.
"The parrotfishes are very important to coral reef health because they eat the algae that would otherwise overwhelm young corals on reefs recovering from natural disturbances," he said.
University of Toronto PhD graduate Jonathan Ruppert said coral reefs were facing pressure from human activity like overfishing, and climate change.
"The reefs provided us with a unique opportunity to isolate the impact of overfishing of sharks on reef resilience, and assess that impact in the broader context of climate change pressures threatening coral reefs," he said.
"Shark fishing appears to have quite dramatic effects on coral reef ecosystems.
"Given that sharks are in decline on reefs worldwide, largely due to the shark fin trade, this information may prove integral to restoration and conservation efforts."
