Drivers of variability in Euphausiid species abundance throughout the Pacific Ocean

Abstract

Using a generalized additive model, we assessed the influence of a suite of physical, chemical and biological variables upon euphausiid species abundance throughout the Pacific. We found that the main drivers of species abundance, in order of decreasing importance, were sea surface temperature (explaining 29.53% of species variability), salinity (20.29%), longitude (−15.01%, species abundance decreased from West to East), distance to coast (10.99%) and dissolved silicate concentration (9.03%). We discuss the influence of these variables within the context of the known ecology and biology of euphausiids. With reference to a previously published model in the Atlantic, we compare the practical differences in the Atlantic and Pacific Ocean. Using projected environmental change from the IPCC A1B climate scenario, we make predictions of future species abundance changes in the Pacific and Atlantic. Our model suggests that species abundance in both oceans between latitudes 30° and 60° (both N and S) will increase due to the temperature rise predicted over the next 200 years, whereas at low latitudes responses are likely to differ between the oceans, with little change predicted for the Atlantic, but species depletion predicted for the Pacific.