Our projects, launched in 2021, has the aim to create a dataset of apex predators which can be found in the waters around Carriacou. Natural sightings are rare, so a technique developed by the SharkLab in Bimini has been deployed which uses baited underwater video surveillance to try to capture these elusive marine creatures without too much impact from divers.
Sharks are crucial to marine ecosystems. They maintain a balance in populations of prey species and keep the ocean healthy by removing ill or diseased animals. They are an important resource supporting local economies through fishing and as an attraction to dive tourists.
By monitoring the diversity and the amount of apex predators we can see, we can determin the relative health and sustainability of our reef ecosystmes. Answering important questions like, is our biomass sufficient to support large predators?
We’re all familiar with the concept of a food chain. Small things are fed on by larger things, all the way up until we reach the big boys! In the water, it’s a little more complex and a little more nuanced...
Of course the sun is still the provider of all energy, and with all the other nutrients in the water the ocean is able to produce dinoflagellates and diatoms, these form most algae in the water. Often referred to as Plankton, they are considered the ‘producer’ of the food chain and are the most abundant food source in the water. This kick starts the food chain.
In nature, everything is designed to work in balance. There is enough dinoflagellates produced to feed all the herbivores and copepods, which means there is enough to feed of the secondary consumers too. The role of the tertiary and apex predators is to ensure that no population of primary or secondary consumer gets too big, and so they have an very important role to play in maintain the balance.
In an environment where any layer of the food chain comes under pressure and their numbers become depressed, this can have a significant impact on the prevalence and density of other marine species. For example, if apex predators are removed from the chain, by fishing, there will be an increase in the numbers of other tertiary consumers. These species would likely over consume secondary consumers. Which would then likely see a spike in primary consumer numbers and a resultant reduction in producers. Once the number of producers in an area go below a sustainable population, then whole chain will collapse.
In Carriacou, what we are seeing here is that the population of Producers is increasing as the primary and secondary consumers are being over-fished. We see this in the proliferation of algae on the reefs. Because there are few secondary consumers, there are even fewer tertiary consumers and the apex predators which we see most tend to be small barracuda’s.
We're planning to expand our research in 2022, wtih putting the surveillance in different locations aorund the island, inclduing sites down towards the south side of Carriacou, where the Atlantic and Caribbean Sea meet.
Join us to discover what apex predators live in the surrounding waters of Carraicou!