For a number of years a marine invasion has been happening in the western Atlantic. In the mid-1980s some lionfish (Pterois volitans) were released in Florida. Since then, they have become established in >4 million km2 of the western Atlantic, Caribbean, and Gulf of Mexico.
The problem is that these invasive lionfish reach higher densities and larger sizes than in their native range (Indonesia). Their hunting method is unlike that of any Atlantic predator as they use prey herding to catch fish and crustaceans which they ingest as a whole (prey can be half their own body size). This has an immense impact on the native reef fish populations in the western Atlantic. Furthermore, little is known of how lionfish numbers are kept stable within their native range. For a long time the problem was the lack of an in-depth understanding of their diet which in turn would help to assess the impact on the native species. Given their hunting mode, lionfish could prey on most fish species within their gape size limits and as a matter of fact the studies showed that they are generalists as many invasive species. Their impact is devastating because of the large number of interspecific interactions they can create or disrupt, particularly in species-rich ecosystems like coral reefs.
Only taxonomically well-resolved diet information combined with prey availability data can help to identify the species most at risk from lionfish predation. Over the last couple of years a number of studies utilized DNA Barcoding of lionfish stomach content, some of those were done here at our facility. Some of my coauthors went further and tried to identify general traits of prey that predict vulnerability to predation, and examine diet selection at different spatial scales. Their work confirmed that lionfish have a voracious appetite and will eat almost any fish smaller than they are, but it also shows that they do have their favorites.
There is much more work that needs to be done in order better understand this rapid invasion and find ways to efficiently fight it. However, it seems we got some help. Students at Woodlawn Beach Middle School in Florida are now participating in a research project by the Gulf Islands Research and Education Center, a partnership between the University of West Florida and the Gulf Islands National Seashore, to try to determine what the lionfish are eating and how much of an impact that is having on the local ecosystem. Their teacher received a grant to bring DNA analysis into the classroom and the students are analyzing stomach content pretty much the same way as we did. Here is a newspaper article (make sure you check out the video on page 2 of it).