Apex Predators and their Importance to Ecosystems
Apex predators sit at the top of the food chain and generally have no natural predators. They play critical roles in maintaining healthy ecosystems as they have significant impacts on the population dynamics of prey species as well as other predators. When apex predators, such as sharks or lions disappear, ecosystems start to unravel as repercussions are felt all the way through the food chain.
Recent scientific research suggests healthy shark populations are linked to coral cover and the health of coral reefs. In a study that assessed the removal of grey reef sharks from a coral reef system, an increase of smaller predators and a decrease in herbivorous or algae-eating fishes was observed. Herbivorous fish are critically important to coral reefs because they eat algae that otherwise smother young corals. Their demise in turn reduces the resilience of coral reefs to recover from disturbance such as from cyclones or bleaching – two impacts that are predicted to increase with climate change.
Vulnerability of Apex Predators
Predators near the top of the food chain are naturally rare as they tend to grow slowly, are late to reach sexual maturity and have relatively low rates of reproduction. These traits also make them especially vulnerable to threats including persecution, overfishing and habitat loss. Recent estimates suggest that around 100 million, and possibly as many as 270 million sharks, are killed around the world each year, with many species removed faster than they can reproduce. Much of this over-exploitation is driven by rapidly growing demand for shark fins, with coral reefs once known for their abundance of sharks targeted and showing drastically reduced shark populations.
Conservation of Flagship Species
Our conservation and research projects currently focus on two important marine predators found at our island sites in Mozambique – the grey reef shark and giant trevally. Targeting these ‘flagship’ species for protection not only helps maintain their populations but has the additional benefit of acting as an umbrella for the protection of many others.