Forage Fish, Jellyfish, Plankton, and Microbes Across Puget Sound—Has It Always Been This Way?

In Puget Sound, an oceanographically diverse and urbanized fjord estuary, understanding of pelagic ecology is poor, and systematic monitoring and assessment of living systems has long been neglected. We explored current patterns of community composition from lower‑to‑middle trophic levels (microbes, phytoplankton, zooplankton, small pelagic fishes, and jellyfish) in surface waters across six oceanographic sub‑basins of greater Puget Sound, and compared fish and jellyfish catch with historical information. In data from monthly sampling of 79 sites from April to October 2011, biological composition differed geographically and seasonally, and assemblage structure from each trophic level correlated with the other trophic levels, and a suite of abiotic attributes. With respect to middle trophic levels, fish dominated in the two northern basins, whereas jellyfish dominated in the three southern basins. Comparing our fish and jellyfish catches with those from the 1970s and 1980s suggests that herring and smelt abundance has declined, and jellyfish abundance has increased, in Central and South Puget Sound but not in the northern basins. Sediment core paleoecological indicators (e.g., diatoms) from Central Puget Sound and Hood Canal indicate that pelagic and benthic food webs may have undergone major changes in the mid-twentieth century, possibly as a result of human activity.