Team of Scientists Hopes to Reveal Fuller Picture on Invasive Species

Today wraps up National Invasive Species Awareness Week, which was marked primarily by a series of awareness-building events and seminars in Washington D.C. It also coincided with the return of CFL grad student, Alex Latzka, from a trip to Germany where he was working with a team of scientists on a new invasive species project. 

When rusty crayfish (center) get too abundant, a lake bottom can go from lush (left), to desolate (right). But is that state the "new normal" or just a blip in the life history of the system?
When rusty crayfish (center) get too abundant, a lake bottom can go from lush (left), to desolate (right). But is that state the “new normal” or just a blip in the life history of the system?

by Alex Latzka
Alex Latzka shows off an especially large virilis (or native) crayfish.
Alex Latzka shows off an especially large virilis (or native) crayfish. Photo: Ali Branscombe

Invasive species are a huge problem for many ecosystems, including our lakes, and they’re continuing to invade new and sometimes unexpected places. One thing scientists are really missing when we study invasions is a big-picture, long-term perspective. This gap is not unique to the study of invasions – not surprisingly, most studies in any scientific field last about as long as it takes to get a PhD.
But, when it comes to invasions, this gap may be critical. What if the first five years of an invasion are remarkably different from what comes after? We often hear stories that this may be the case. “There used to be way more rusty crayfish in our lake when I was growing up,” or “I never used to see this many snails,” are anecdotes I’ve heard when discussing invasives with people who have lived on a lake for many years. And research supports some of these claims – there are scientific papers documenting similar patterns at single sites for single species.
This map of Wisconsin shows known lakes with rusty crayfish invasions. Image: Alex Latzka
This map of Wisconsin shows known lakes with rusty crayfish invasions. Image: Alex Latzka

Even though an invasive species may be very abundant and have nasty impacts now, it may not be so successful in the future. And, even if another invasive species is at low levels and not causing problems now, that may soon change. For managers of invasive species, these patterns – or what we like to call dynamics – are crucially important. If we know that it’s likely an invasive species population is going to crash down to non-harmful levels, maybe we shouldn’t invest a lot of money and effort to control it.
Likewise, we may not want to ignore an invader that is currently at low levels, because it may have serious impacts in the future. The crucial question is – are we making observations of superabundant invasives species because that’s the common population trajectory? Or are they, perhaps, just more noticeable at the moment?
It was exactly these kinds of questions, and the recognition of this critical information gap, that motivated me and fellow CFL graduate student, Ali Mikulyuk, to try to bring together researchers and long-term data to assess how often invasives overrun an ecosystem and what the causes of such dynamics might be. Prompted by a class led by Emily Stanley that urged us to use data from all over the US Long Term Ecological Research network, we began contacting scientists from across the country, identifying and compiling appropriate datasets, and stumbling through data management and analyses that we were mostly unfamiliar with. We led a workshop bringing these scientists and their ideas together in late 2012.
While all of this was happening, another ecologist in Europe – Jonathan Jeschke, a professor at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries in Berlin – was essentially starting to do the same thing. Luckily, we each contacted a key figure in the science of invasive species – David Strayer, a freshwater ecologist at the Cary Institute of Ecosystem Studies. Strayer put us in touch with one another so that we could share the burden of this monstrous project, rather than duplicate each other’s efforts.
Team Science: scientists involved in the new InDyn  project recently gathered in Germany. Photo courtesy of Alex Latzka.
Team Science: scientists involved in the new InDyn project recently gathered in Germany. Photo courtesy of Alex Latzka.

Last week marked the kickoff of this new collaboration. I attended a workshop that brought together scientists from all over Europe, and a few from North America, to begin an international synthesis on the long-term dynamics of invasive species. InDyNet (Invasives Dynamics Network) is funded by the German Research Foundation DFG and will bring together the data Ali and I already collected, along with many other datasets, to assess these long-term dynamics, evaluate their causes, and ask a series of other questions that we will be uniquely suited to answer with so much data from all over the world.
Ultimately, we hope to shed light on invasives from this long-term perspective. Hopefully, our findings will be able to give us a bit more information so that people affected by invasions may have more of an idea of what to expect in the future, and so that the agencies and managers tasked with protecting our natural resources can do so wisely – aware of what the future may hold for a particular invader.
 

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