Journal of Paleolimnology

, Volume 30, Issue 2, pp 183–193

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

  • Jon N. Sweetman
  • Bruce P. Finney

DOI: 10.1023/A:1025543421436

Cite this article as:
Sweetman, J.N. & Finney, B.P. Journal of Paleolimnology (2003) 30: 183. doi:10.1023/A:1025543421436


Stratigraphic changes in the remains of Bosmina longirostris from a lake with an introduced sockeye salmon population and a lake with a natural salmon run on Kodiak Island demonstrated markedly different responses to past fluctuations in salmon populations. In both lakes, there was a positive correlation between the density of Bosmina microfossils and the abundance of sockeye salmon. However, opposite size trends were observed in the two lakes. In Karluk Lake, which has a native sockeye salmon population, Bosmina mean carapace lengths were largest at high salmon densities, and mean mucro and antennule lengths were also large, suggesting strong predation pressure from cyclopoid copepods, and less intense pressure from juvenile sockeye salmon. As salmon-derived nutrients are important in driving primary productivity in this system, changes in zooplankton productivity track salmon escapement, but grazing pressure on Bosmina from juvenile salmon is less important than that from cyclopoid copepods. In Frazer Lake, a lake with an introduced salmon population, Bosmina morphologies were smallest during periods of high sockeye salmon in the lake, suggesting much stronger predation effects from sockeye salmon due to the suppression of Cyclops columbianus. Latent development of compensatory mechanisms and the delayed recovery of copepod populations to salmon introductions has resulted in zooplankton populations that are still recovering from shifts in fish populations that occurred decades earlier. The differential response of Bosmina populations between the natural and manipulated lakes suggests that care must be taken when attempting to extrapolate results from whole-lake manipulations and short-term experiments to natural systems.

Bosmina longirostris Cyclops columbianus Marine-derived nutrients Oncorhynchus nerka Predation Sockeye salmon Trophic dynamics 

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • Jon N. Sweetman
    • 1
    • 2
  • Bruce P. Finney
    • 2
  1. 1.Paleoecological Environmental Assessment and Research Laboratory (P.E.A.R.L.), Department of BiologyQueen's UniversityKingstonCanada
  2. 2.Institute of Marine Science, School of Fisheries and Ocean SciencesUniversity of Alaska FairbanksFairbanksUSA

Personalised recommendations