GLIN==> UPCOMING SEMINAR

[Kanika Suri <Kanika.Suri@noaa.gov>]

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

Abstract:
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
48105

734-741-2147



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