IISG’s science writer, Anjanette Riley, is at the 2013 International Association for Great Lakes Research conference at Purdue University. She’ll be blogging from the sessions all week providing an inside look at the newest research on the health of the Great Lakes. Here’s today’s post:  

“There is more food for Asian carp in Lake Michigan than people thought. In a morning filled with new insights into these invasive species’ biology and potential impact in the Great Lakes, this fact rang the loudest for me. I have read some of the research in recent years speculating that Asian carp could not survive in much of the Great Lakes, which have less of the phytoplankton and zooplankton than the ravenous eaters need. What my fellow session attendees and I learned this morning, though, is that the plankton population has been underestimated. There are more–much more–of the smallest species living in the nearshore waters of Lake Michigan than previously believed. 

According to researchers from the Illinois Natural History Survey, the cause of the miscalculation is a common testing method that uses a filter too large to trap many of the microscopic species in the lake. Additional testing measures show that the number of some plankton species found in the lake is roughly the same as in rivers where Asian carp are known to thrive, like the Ohio and Missouri Rivers. And there are plankton species in the lake that are not found in many of these waterways. Taken together, this means that likelihood that Asian carp can make Lake Michigan their home may be higher than previous data has indicated. 
The session this morning also taught me that carp will branch away from their favorite dish to eat the particulates from decomposed animals and plants that line the floors of lakes and rivers. These exist in much higher numbers than plankton and their stock is continuously replenished as aquatic matter dies. Although it is still unknown whether Asian carp would choose this food over others (or eat it only when there is nothing else), this could mean that plankton in the Great Lakes may not have to bear the brunt of the carp’s huge diet alone if the invasive fish were ever to take up residence.”
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