Existence of coral reefs is under threat due to the climate crisis. However, a new study claims that king crabs could help save them by keeping excessive seaweed growth under control.
Researchers from the Florida International University found that experiments on the Florida Keys showed the Caribbean king crab is better than other species at removing overgrown seaweeds that threaten the reefs, by eating it.
The study found that the crab species reduced seaweed cover by 50 per cent, when they were introduced to experimental plots on coral reefs. Once the species are boosted in the wild, it could help combat the seaweed – which is spreading quickly due to climate change, and restore coral reefs, which have been projected to completely disappear by the year 2100.
Existence of corals is threatened by rising sea temperatures, which leads to coral bleaching, as well as more acidic waters, pollution, disease and more. Study author Mark Butler, who is a professor at Florida International University, told the DailyMail that this study has opened up a whole new avenue for coral reef restoration.
He added that by experimentally increasing the abundance of large native, herbivorous crabs on coral reefs in the Florida Keys led to its rapid declines in seaweed cover and, over the course of a year or so, resulted in the return of small corals and fishes to those reefs. Butler believes that factors like overfishing, climate change, disease and eutrophication, overly-enriched waters leading to excessive growth of algae have fuelled the overpopulation of seaweeds on reefs, particularly in the Caribbean, researchers say.
Butler further added that the fleshy macroalgae (seaweeds) that occur on coral reefs have several negative effects on corals when the seaweeds are too abundant. Some of those effects include taking up space on the reef that hinders new larval corals to settle and get established.
Overgrowing seaweed also does not allow the corals the sunlight, which the coral's own symbiotic algal cells need to survive. The seaweeds also release chemicals that stress coral, which reduces coral reproduction and makes coral more susceptible to disease.
According to researchers, many reefs have undergone an ecological phase shift in the Caribbean waters because of which seaweeds now dominate previously coral-rich reefs. Seaweed overgrowth also promotes proliferation of reef sponges which are simple aquatic animals with dense, yet porous, skeletons which detriments the life cycle of corals. The research was restricted to Florida Keys which is a string of tropical islands stretching about 120 miles off the southern tip of the US state.