Large Nonlethal Effects of an Invasive Invertebrate Predator on Zooplankton Population Growth Rate

We conducted a study to determine the contribution of lethal and nonlethal effects to a predator's net effect on a prey's population growth rate in a natural setting. We focused on the effects of an invasive invertebrate predator, Bythotrephes longimanus, on zooplankton prey populations in...

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Bibliographic Details
Published in:Ecology (Durham) 2007-02, Vol.88 (2), p.402-412
Main Authors: Pangle, Kevin L., Peacor, Scott D., Johannsson, Ora E.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Biological and medical sciences
Biomass
Bosmina longirostris
Botany
Bythotrephes
Bythotrephes longimanus
Cladocera
Crustaceans
Daphnia
Daphnia mendotae
Daphnia retrocurva
Ecology
Ecosystem
Field study
Field surveys
Fresh water ecosystems
Freshwater
Freshwater ecology
Fundamental and applied biological sciences. Psychology
General aspects
Great Lakes
Great Lakes Region
invasive species
Invertebrata
Limnology
Marine ecology
nonlethal effects
Nonnative species
Plankton
Plant populations
Population Growth
Population growth rate
Predation
Predators
Predatory Behavior
predator–prey interactions
Synecology
Temperature
trait-mediated indirect interaction
Vertical distribution
vertical migration
Zooplankton
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Summary:We conducted a study to determine the contribution of lethal and nonlethal effects to a predator's net effect on a prey's population growth rate in a natural setting. We focused on the effects 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 the prey species Daphnia mendotae, Daphnia retrocurva, and Bosmina longirostris inhabited deeper portions of the water column as Bythotrephes biomass increased, possibly as an avoidance response to predation. This induced migration reduces predation risk but also can reduce birth rate due to exposure to cooler temperatures. We estimated the nonlethal (i.e., resulting from reduced birth rate) and lethal (i.e., consumptive) effects of Bythotrephes on D. mendotae and Bosmina 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 derived from laboratory studies. Results indicate that nonlethal effects played a substantial role in the net effect of Bythotrephes on several prey population growth rates in the field, with nonlethal effects on the same order of magnitude as or greater (up to 10-fold) than lethal effects. Our results further indicate that invasive species can have strong nonlethal, behaviorally based effects, despite short evolutionary coexistence with prey species.
ISSN:0012-9658
1939-9170
DOI:10.1890/06-0768