Salish Sea Ecosystem Conference

Regional and temporal variability in Puget Sound zooplankton: bottom-up links to juvenile salmon

We use data from the Puget Sound Zooplankton Monitoring Program to explore patterns of spatial and interannual variability in zooplankton communities in response to environmental change during 2014-2017. This program is a collaborative effort involving 10 tribal, county, state, federal, academic, and nonprofit entities initiated via the Salish Sea Marine Survival Project with the goal of understanding the key role of zooplankton in food webs and ecosystems. Large interannual differences in the environment over this period strong effects on zooplankton community structure and abundance. 2014 began as a fairly normal year in Puget Sound until the Pacific Warm Anomaly event nicknamed “The Blob” began to affect the region during late summer and fall. Unprecedented warm anomalies occurred in summer 2015, persisting through 2016. Off the coast of Washington and Oregon, clear effects on zooplankton community structure were observed, with rare oceanic species occurring in coastal samples concurrent with decreased overall biomass. In sharp contrast, few rare species were collected in Puget Sound, and zooplankton increased in 2015 and 2016 relative to 2014, including increases in nearly all taxa that are important juvenile salmon prey. A few taxa, most notably the dinoflagellate Noctiluca and numerous species of small jellyfish, decreased during the warm years, and shifts in the seasonal phenology of some taxa were observed. These and other findings from the Puget Sound Zooplankton Monitoring Program will be presented in the context of the implications of environmental change for juvenile salmon growth and survival.