UW Aquatic & Fishery Sciences Quantitative Seminar

Liz Atwood

Quantitative Ecology and Resource Management, UW

Mesoscale eddies and ichthyoplankton community composition and abundance in the Gulf of Alaska


Dispersal of fish eggs and larvae (ichthyoplankton) from spawning grounds to juvenile nursery habitats influences growth, survival, and recruitment. Trajectories are affected by environmental factors such as currents, winds, and basin-wide atmosphere-ocean coupling (e.g. East Pacific – North Pacific teleconnection). In the Gulf of Alaska, mesoscale eddies (100 – 200 km in diameter) propagating along the shelf-break can increase cross-shelf flow and affect nutrient, chlorophyll, and zooplankton communities in the basin. Despite their ubiquity, eddy influence on ichthyoplankton species composition and diversity has not been described for the Gulf of Alaska. Evidence of larval fish entrainment by these eddies was examined by comparing shelf, slope, and eddy ichthyoplankton assemblages in the northern Gulf of Alaska (2002 – 2004), and a cruise in 2005 that sampled three eddies during or soon after formation. We also investigated association between eddy activity and annual shelf larval fish abundances, comparing effects of eddies to local and basin-wide physical forcing factors on larval fish abundances. Statistical methods cover hierarchical cluster analysis, Non-metric Multidimensional Scaling, Indicator Species Analysis, Generalized Linear Models, and Generalized Linear Mixed Models. Results suggest that mesoscale eddies propagating along the continental shelf-break influence larval fish assemblages over the shelf and slope.

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