Presenter: Bethany Wager (West Virginia University)

Description:
The ecological impacts of jellyfish blooms on fishes and the ecosystems they inhabit are not well understood. Though jellyfish may have direct and indirect effects on fishes, they are often considered bycatch and excluded from the data collection process in many studies. However, by using a comprehensive data set of habitat, fish, jellyfish, and plankton data from Puget Sound, WA in 2011, we investigated the potential ecological impacts of jellyfish blooms on the surrounding ecosystem. We tested the following possible hypotheses of ecosystem impacts of jellyfish: competition with and displacement of pelagic fish, predation upon zooplankton and ichthyoplankton, phytoplankton production through predator release, and detritivore activity through decadence of medusae. Preliminary results suggest some support for most of these hypotheses. Our sites comprised four geomorphic types and we found differences in jellyfish biomass between these geomorphic types. We also investigated jellyfish bloom impacts while controlling for temporal and spatial variation. These analyses revealed systematic differences across sub-basins in the slopes of dependent variables and jellyfish biomass.  If these results provide insight into causal effects of jellyfish on the pelagic environment, they have important implications for management of threatened fishes such as the Chinook salmon in Puget Sound because jellyfish appear to simultaneously compete for food and alter the pelagic community composition.