February 22, 2021
How Sharks Help Keep Coral Reefs Healthy
- as seen by -Sarah Markes and Tim Davenport @WCS_Tanzania
No species can survive in isolation. From food chains and nutrient cycles, to disease control and climate regulation, suites of species are integral parts of healthy ecosystems, reliant on their stability. Sharks are no exception, with both reef-living and deeper-sea species playing important roles in healthy coral reefs. They do this through maintaining food webs and fish stocks, cycling nutrients, reducing disease, and helping regulate invasive species. Sharks even help mitigate the effects of climate change through supporting carbon sequestration by healthy coral.
Sharks’ role as top predators in marine food chains is especially important for coral reef health. By eating large predatory fish species such as groupers, sharks regulate their populations. This means more of the smaller fish diversity that groupers eat survive. Many of these smaller fish, such as parrot fish, are grazers that eat algae on the reef. Too much algae reduces the ability of zooxanthellae in the coral to photosynthesize, leading to reef degradation and ultimately death. So, grazing fish keep coral healthy – thanks to predator regulation by sharks!
Given the importance of sharks for reef and marine health, it is important that sharks are themselves protected. Worryingly, shark numbers around the world have decreased rapidly in recent years – primarily due to overfishing. This is one of the issues that WCS is working to address across East African and Madagascan waters. This poster was created as part of this work, to explain the benefits of sharks to coral reefs and people. It is available in English, Kiswahili, Portuguese, and Burmese. Please email email@example.com for print resolution pdfs.