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Dr. Scott Peacor from the Great Lakes Environmental Research Laboratory(GLERL), will be giving a seminar on May 18 as a part of the NOAA/ University of Michigan Great Lakes Seminar Series. Please find details of his talk listed below.

Speaker: Dr. Scott Peacor

Title: Nonlethal Effect of an Invasive Invertebrate Predator, /Bythotrephes/, on the Population Growth Rate of Zooplankton Prey in Lakes Michigan and Erie

Date: Thursday, May 18

Time: 10:30 AM

Location: GLERL, 2205 Commonwealth Blvd., Ann Arbor, MI, 48105

We evaluated the nonlethal effects (i.e. due to induced phenotypic modifications) relative to lethal effects (i.e. through consumption) of an invasive invertebrate predator, /Bythotrephes longimanus/, on zooplankton prey populations in Lakes Michigan and Erie. Field data taken at multiple dates and locations in both systems indicated that prey species, /Daphnia mendotae/, /Daphnia retrocurva/, and /Bosmina longirostris/ inhabited deeper portions of the water column as /Bythotrephes/ biomass increased, demonstrating the generality of this response. This induced behavioral response is supported by laboratory experiments. Whereas the induced migration reduces predation risk, it comes at the cost of reduced birth rate, due to inhabiting regions of lower temperature. We estimated the nonlethal (i.e., resulting from reduced birth rate) and lethal (i.e., consumptive) effects of /Bythotrephes/ on /D. mendotae/ and /B. longirostris/. These estimates used diel field survey data of the vertical gradient of zooplankton prey density, /Bythotrephes /density, light intensity, and temperature, with growth and predation rate models based on laboratory studies. Results indicate that nonlethal effects play a substantial role in the net effect of /Bythotrephes/ on prey population growth rate, with nonlethal effects on the same order of magnitude or greater (up to 10 fold) than lethal effects. This study therefore demonstrates that nonlethal effects can contribute substantially to net predator effects on prey at the population level in an uncontrolled field environment. Results of a simple model are presented that predict this result. Our results further indicate that invasive species can have strong nonlethal, behaviorally-based effects, despite short evolutionary coexistence.

If you have any questions or concerns, please email me at kanika.suri@noaa.gov; or call 734-741-2147.

For more information about the seminar series, please visit our website at http://www.glerl.noaa.gov/news/seminars/


Kanika Suri
Center of Excellence for Great Lakes and Human Health (CEGLHH)
2205 Commonwealth Blvd.
Ann Arbor, MI


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