Ecological Impact of Lionfish

When invasive species are introduced to a new ecosystem, they often cause a disruption to the natural balance of the ecosystem. The introduction of lionfish into the Atlantic and Caribbean is one of the factors that have helped contribute to the disruption of the coral reef communities along the eastern coast of the United States and the Caribbean.

Invasive lionfish have shown to be exceptionally effective predators upon twenty-one different families of small reef fishes as well as numerous different species of crustaceans. In the Caribbean, their feeding preferences have caused them to be in direct competition for food with snappers and groupers. Juvenile lionfish tend to feed mainly on crustaceans while the adults prey almost exclusively on fish.

The hunting strategy employed by lionfish is quite unique and effective against Caribbean species that have never encountered a predator like them. Lionfish coloration, elongated fins, and slow movements give them the appearance of seaweed, crinoids or other harmless marine species. They move slowly towards their intended prey fanning out their pectoral fins, often trapping their intended meal against the reef. Once close enough, lionfish will forcefully suck their prey into their mouths. Atlantic and Caribbean species have never encountered a predator of this type during the course of their evolutionary history. Native prey do not appear to make any efforts to take evasive action until it is too late.

Lionfish have shown to exhibit a higher consumption rate when compared to similar sized native predators. They have been recorded to have 2.4 times the negative impact upon reef fish populations compared to the native predators in the same environment. One study conducted in the Bahamas discovered that lionfish reduced the prey fish population by 90% over the course of two months compared to a 35% reduction of reef fish populations by the native coney grouper.

A significant concern is that if invasive lionfish continue to deplete their preferred prey base they will eventually turn towards consuming juveniles of economically important species. The loss of the preferred prey base will also produce a ripple effect through the coral reef ecosystem since most of the prey species are herbivores that help control the growth of algae on the reef. Removal of these herbivores leads to an increase in algal growth which eventually leads to a decrease in the survival rate of corals. These negative impacts, along with a variety of other factors, are contributing to a decline in the stability of the coral reef ecosystems throughout the Atlantic and Caribbean.

Additional Resources:

Dave Cox is an Associate Professor of Biology, author, and President of Howler Publications. He leads yearly study abroad trips to Belize, for students and community members, to study tropical ecology, marine biology and Mayan culture. If you would like to join Professor Cox on a lionfish hunt in Belize this May contact him at [email protected] for more details.

This is the second part of our series on the ecological impact of lionfish. These articles are being developed to support our latest textbook project.

Image credits:

Lionfish: By T.Voekler (Own work) [Copyrighted free use], via Wikimedia Commons

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