Differential responses of zooplankton populations (Bosmina longirostris) to fish predation and nutrient-loading in an introduced and natural sockeye salmon nursery lake on Kodiak Island, Alaska, USA.

Authors: J.N. Sweetman and B.P. Finney
Pub. no.: RP-03-03
Year: 2003
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The authors assessed the historical response of zooplankton to salmon variability in two Alaska lakes, from sediment cores. In a lake with native sockeyes, cores showed that Bosmina were large when salmon were abundant, suggesting strong predator pressure from cyclopoid copepods. In a lake with introduced salmon, Bosmina were smallest when there were lots of salmon, suggesting stronger predation by juvenile salmon because Cyclops were suppressed. The authors observed that zooplankton still seem to be recovering from shifts in fish populations that occurred decades earlier. Thus they advise trophic modelers to be cautious when extrapolating results from short-term experiments with manipulated lakes. Journal of Paleolimnology 30:183-193.