Coral reefs have been dying off in record numbers over the past few years, with scientists linking warming ocean waters as the prime cause. But a new study has found that the depletion of fish could also be a contributing factor.
Fish tend to inhabit areas of coral, and are an important factor in their overall health. One reason is because when fish urinate, they release phosphorus into the water which, together with nitrogen released through the gills of fish, provide important nutrients necessary for coral.
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A new study appearing in Nature Communications has found that in coral reef regions where fishing takes place, the reefs have 50 per cent fewer nutrients, which includes phosphorus and nitrogen.
The researchers studied 143 species of fish at 110 locations across 43 Caribbean reefs where varying degrees of fishing occurred and where it was banned.
“Part of the reason coral reefs work is because animals play a big role in moving nutrients around,” said lead author Jacob Allgeier, a postdoctoral researcher at the University of Washington’s School of Aquatic and Fishery Sciences.
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Larger fish were particularly influential in providing the reefs with the necessary nutrients. Allgeier actually spent four years measuring the amount of nutrients in fish pee as well as fish tissue.
“Simply stated, fish biomass in coral reefs is being reduced by fishing pressure. If biomass is shrinking, there are fewer fish to pee,” said Allgeier.
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