Brave New World?

It took me till the age of 37 to see my first Lionfish in the wild. I was leading an ecotourism expedition to Palau. I dropped into the warm water at the popular Big Drop-Off, an enormous coral wall off the island of Ngemelis. As soon as all the bubbles cleared around me and I could orient myself to the reef edge, right there–out in the open in full daylight–were two big and beautiful Lionfish. A rare sighting as they are crepuscular and nocturnal fish and prefer dark overhangs and other nooks during the day. The point of this preamble is that I waited almost half-a-lifetime to see an amazing fish that has been an icon of vibrant coral reefs since I was a child.

Imagine my mixed feelings when, while perusing images from various Earth Day 2007 clean-up efforts by ocean-loving people around the world, I came across pictures of a Lionfish eradication project. A group of 44 volunteers set sail through the western Bahamas collecting data and Lionfish specimens for further examination. This was a concerted effort to remove an invader... in this case Lionfish. I scanned through, to me, startling images of clean-up bags stuffed with Lionfish. Lionfish lined-up on the dock for counting and dissection. And a close-up of a speared lionfish. Come-on... people spear-fish all the time. I had to temper my affinity for lionfish with the reality of these animals as a harmful, invasive species.

I've known for quite a while that the Common or Red Lionfish (Pterois volitans/miles) sightings have been escalating in the Western Atlantic. Lionfish are native to the Indo-Pacific region, and their introduction and range expansion has negatively impacted coastal ecosystems and the services these ecosystems provide. Evidence seems to point to aquarium specimen release as the likely vector for Lionfish populations taking-hold in the Caribbean. Whatever the source, Lionfish are establishing themselves and hardy populations are out-competing native or endemic species in the Bahamas and along the coast of Florida.

Lionfish are voracious ambush predators. In areas of the Western Atlantic where Lionfish populations have established, they have quickly decimated native juvenile populations of many native species. Stomach contents of the Lionfish posted here from the Bahamas showed juvenile wrasses, damsels, even small crustaceans. Lacking natural predators–and with a diet essentially mirroring that of groupers–Lionfish expansion in the Western Atlantic can quickly spell the demise of an important local food fish. Conversely, some dive tourism providers are doing what they can to capture tourist interest (and dollars) in seeing Lionfish in the Atlantic. After all, it's a lot cheaper than a flight to Australia.

While the upper range for Lionfish sightings was presumed to be Florida and perhaps as far north as the Carolina's, a recent Lionfish incursion as far north as Jamestown, Rhode Island was recorded in October 2006. Why so far north? In part it has to do with the Gulf Stream which seasonally pushes warm Caribbean water up the eastern US coast till it hits Cape Cod and is then deflected to Ireland.

But short- and long-term climate changes and their impacts on ocean temperatures can also influence the distribution of fish species in their range. The ecosystem consequences of these interactions are even more poorly understood than the consequences of invasive species alone. I'll show a little home team favoritism and refer you to the excellent work of Jay Stachowicz, at UC Davis' Bodega Marine Lab. Part of his research interests involve climate change and biological invasions. (I spent many a memorable summer working with ocean science-geek high school students at BML in beautiful Bodega Bay, California, and thought I'd throw a little link-love in their direction).

Last week, the journal Science published an ecology news story, Back to the No-Analog Future? (Science 11 May 2007: Vol. 316. no. 5826, pp. 823 - 825). In it, John Williams of the University of Wisconsin, Madison, and Stephen Jackson of the University of Wyoming in Laramie––scientists studying transitions in terrestrial North American ecosystems––have uncovered a process that I find potentially analogous to and foreshadowing of the Atlantic Lionfish situation,

During the last North American ice age, as the Laurentide Ice Sheet retreated into Canada 17,000 to 12,000 years ago, the region from Minnesota to Ohio to Tennessee supported a forest of spruce, sedge, oak, ash, and hophornbeam--an ecosystem that simply doesn't exist today, despite the fact that all of those species still survive. These odd communities--called "no analog" ecosystems because no modern counterparts for them exist--likely arose from odd combinations of climate variables such as precipitation, temperature, and seasonal variations that also don't exist today.

They think this process is at play today based on climate records and models which indicate, at least for land, novel climates are likely to develop no-analog ecosystems as early as 2100.

The report describes that new terrestrial climates are expected to cause ecosystem reshuffling as individual species, constrained by different environmental factors, respond differently. One of the biggest issues raised by novel and disappearing climates is whether species whose preferred climates disappear locally can migrate to other areas where suitable climates still persist.

Which brings me back to Lionfish. While oceanic systems are more stable than terrestrial, let's assume that climatic changes and ecosystem reshuffling to no-analog states could occur in marine ecosystems as they do on land. What, then, defines an "invasive species?" For sure, Lionfish in the Western Atlantic present a rather more clear-cut case as their presence is most likely the result of human introduction. But as novel oceanic climates allow other non-native species to expand their range, how do we define "invasive species" then? Who's a native or non-native as ranges expand in response to climate change? Ecosystem reshuffling has happened numerous times in the history of life in the ocean. But it's the tempo of the looming oceanic reshuffling that is particularly worrisome.