“Sure, but can estuarine lionfish handle freshwater inflow events? Won’t they get wiped out every time a hurricane or soaking cold front passes through the region? Do we really have anything to worry about”? These are some of the most common questions we hear when discussing estuarine habitat use by lionfish.
Click here to watch a video clip I shot in the Loxahatchee River during a period of extreme freshwater discharge following the passage of Tropical Storm Issac – the answers to the above questions will become startlingly clear.
Since rain bands from Tropical Storm Issac stalled over southeast Florida in late August, setting rainfall records throughout the region, massive amounts of freshwater have been continuously pouring into the Loxahatchee River through a series of canals and flood control structures. Salinity values plummeted throughout the estuary, killing nearly 100% of the oysters living at our most upstream research site. Closer to the ocean, dozens of dead queen conch littered the bottom of the estuary, victims of lethally low salinity. However, despite this torrent of turbid, tannin-stained water, lionfish are still alive and well in the estuary. In just a few minutes of searching earlier this week, we were able to find 10 lionfish nearly 1.5 miles from the ocean (in the same area where the dead conch were found). This really isn’t much of a surprise in light of our recent discovery of a lionfish more than four miles from the ocean at one of our oyster reef restoration sites, where salinity was only 8 ppt. However, I was still holding on to the hope that a month of raging freshwater inflow would purge our system of these tenacious invaders.
It’s beginning to look like salinity isn’t as big of a barrier to lionfish dispersal as we had previously thought. This has implications here in Florida, where many estuarine systems, including the ecologically important Indian River Lagoon, may be harboring undetected populations of the striped invader (hence the need for the upcoming Indian River Lagoon Lionfish Megatransect). Looking at the bigger picture, it’s possible that the discharge plumes of the Amazon and Orinoco Rivers, previously considered a relatively impermeable barrier to lionfish range expansion, may actually do little to slow the species’ southward spread around the coast of South America.