Over the course of human existence various species have been accidentally and intentionally introduced into new environments. This often leads to serious environmental consequences. Native species are often pushed into extinction by the invasive species, leading to an imbalance in the ecosystem. Kudzu, the Emerald Ash Borer, and lionfish are all examples of species that were intentionally or accidentally introduced into the United States. Each of these species has created an ecological nightmare for the various ecosystems that they inhabit.
The lionfish (Pterois volitans) is a top level predator among the coral reefs and rocky shores of the Indo-Pacific. Their natural range extends from Australia and Malaysia in the west to French Polynesia in the east. Their north to south distribution extends from Japan to New Zealand.
Pterois volitans can be recognized by their long flowing dorsal spines, fleshy tentacles above their eyes and below their mouth, and having a brown to maroon body that is vertically crossed by white vertical stripes. Their distinctive color pattern is what gives them the common name lionfish or zebrafish .
They can grow as large as 18 inches, with the average being closer to 12. Their 13 needle-like dorsal fins contain a potent toxin that serves as powerful defensive weapon against most would be predators. If careless divers or snorkelers come into contact with the spines it can lead to a painful sting causing nausea and shortness of breath. Fatalities from lionfish spines are rare.
Lionfish can be found across a wide range of marine habitats ranging from hard bottoms, mangroves, and sea grass beds to coral reefs and artificial habitats like shipwrecks. They can also be found in as little as 1 foot of water and as deep as 1000 feet. The juveniles tend to be found in the shallower areas while adults reside in the deeper regions. Lionfish were first reported in the Atlantic as early as 1985. By the early 2000s it was confirmed that they had established an Atlantic population. Their Atlantic / Caribbean range extends from New York to Bermuda with populations spreading towards South America. In some regions the lionfish density has been reported as high as 1,000 individuals per acre, surpassing the density of several native species.
Native reef fish communities have been severely impacted by the spread of this invasive predator due to them occupying the same ecological role as fish like snappers and groupers. While they occupy the same trophic level as snappers and groups, lionfish do not have any natural predators in the Atlantic and Caribbean ecosystems. This allows their population to grow exponentially with little to no regulation.
Pterois volitans are hampering restocking efforts of several economically important fish species as well as disrupting coral reef conservation measures. Studies have shown that lionfish place a significant amount of pressure on native coral-reef fish communities and may lead to substantial deleterious changes in these communities.
Additional Resources:
- National Invasive Species Informative Center (USDA)
- NOAA Lionfish Biology Fact Sheet
- Nonindigenous Aquatic Species (USGS)
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.
Image Credits:
Lionfish: By T.Voekler (Own work) [Copyrighted free use], via Wikimedia Commons
Map: NOAA
