Alien lionfish threaten reef fish


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Rising numbers of predatory Lionfish are causing concern on coral reefs in the Caribbean Sea.

A new study has found that the invasive alien species, which originates from the Pacific and Indian Oceans, is reducing the juvenile reef fish populations in the region by up to 80%.

Scientists now seek a method of managing the Lionfish s exploding population before it causes a major crisis.

The threats to coral reefs all over the world were already extreme, and they now have to deal with this alien predator in the Atlantic, said Mark Hixon, a professor at Oregon State University.

We ve observed that they feed in a way that no Atlantic Ocean fish has ever encountered. Native fish literally don t know what hit them.

Lionfish, Pterois volitans, are capable of swallowing prey two-thirds their own size, and during the study one was observed to consume 20 small fish in 30 minutes.

Studies carried out on controlled plots found that the Lionfish were able to reduce juvenile fish populations on the reefs by 79% in just five weeks.

However, the depopulation of the reefs is only part of the immediate problem.

It is feared that a reduction of herbivorous fish on the coral reefs due to the Lionfish invasion could have devastating knock-on effects for the overall balance of the ecosystem.

The seaweeds that the native reef fish, including parrotfish, control could consequently be allowed to proliferate, and smother the diverse coral population present on the reefs.

We have to figure out something to do about this invasion before it causes a major crisis, said Hixon.

We basically had to abandon some studies we had under way in the Atlantic on population dynamics of coral reef fish, because the lionfish had moved in and were eating everything.

Lionfish protect themselves from predators using venomous dorsal spines; however these haven t proved necessary in their new home.

The Groupers known to predate on Lionfish in the Pacific Ocean have been over-fished in the problematic Atlantic Ocean, meaning there is very little control over the population.

It is believed that the Lionfish were introduced into the Atlantic Ocean through the release of aquarium specimens off the coast of Florida during the early 1990s.