The effects of the anomalous warming on lower trophic levels in the NE Pacific, from Continuous Plankton Recorder sampling.

Continuous Plankton Recorders (CPRs) were first deployed in the NE Pacific in 2000 so that there is now a 15 year time series of taxonomically resolved, lower trophic level abundance data. During this time the ocean has experienced periods of warmer and colder conditions, as indexed by the Pacific Decadal Oscillation, with noticeable responses in the plankton such as a higher abundance of warm water species and a more northerly distribution in warm years, or a later spring zooplankton increase in colder years. This presentation will compare 2014 data, collected during the anomalous warming, with the preceding time series for two contrasting regions that had good CPR sampling coverage; the oceanic NE Pacific and the central Alaskan Shelf. Preliminary findings suggest that some of the planktonic responses to the anomalous warming were in-line with previous warm conditions in the mid-2000s, but some were not. For example: The larger diatoms that the CPR samples were unusually low in both region and comprised a higher proportion of long, narrow cells than normal. Zooplankton biomass was very high through 2014 on the Alaskan shelf and the previously strong positive relationship between diatoms and zooplankton biomass did not hold true in 2014. Warm water copepods were more numerous in both regions than in recent cold years, but not as numerous as expected in the oceanic region. Some speculative conclusions will be drawn and it is hoped that these data can contribute to a larger understanding of the impact of the unusual conditions on the marine ecosystem.