2018 Puget Sound Marine Waters Overview

A new report from the Puget Sound Ecosystem Monitoring Program says climate change altered the base of Puget Sound's food web in 2018, diminishing microscopic phytoplankton necessary for marine life. Scientists also observed lower abundances of fish, seabirds, and marine mammals.


This report provides a collective view of 2018 Puget Sound marine water quality and conditions and associated biota from comprehensive monitoring and observing programs. It is the eighth annual marine water quality report from the Puget Sound Ecosystem Monitoring Program (PSEMP) Marine Waters Work Group. According to PSEMP, the report "details the effects of a changing climate on Puget Sound in 2018, and describes how these changes trickled down through the ecosystem to affect marine life and seafood consumers."

Report summary

In 2018, Puget Sound’s marine waters most closely resembled 2017—though with a few startling differences. Water temperatures were mostly warmer than average, except for a cold spell in February–March. They were warmer than in 2017, though not as hot as during the years of “the Blob” (the marine heatwave of 2014–16). The Sound’s salinity (saltiness) in 2018 followed a similar pattern to that observed in 2017, responding to a near- record-setting wet spring (fresher) followed by a record-setting summer drought (saltier). Salinity went up everywhere through the summer and fall, with some exceptional values recorded. Earlier runoff and summer droughts is what we would expect based on climate-change predictions for the region. Hypoxia (a lack of oxygen) was more apparent in 2018 than previous years, though no fish kills were reported.

Marine populations had differing responses during this post-Blob year that was still generally warmer-than-normal. The most notable differences were at the base of the food web; the spring phytoplankton bloom was delayed and large, but overall, chlorophyll values and phytoplankton biovolume were greatly reduced in 2018 compared to previous years. There was a marked increase
in Vibrio bacteria-related illnesses in 2018, with illness counts exceeding those during the last major outbreak in 2006. Zooplankton abundances were similar to or lower than in 2017, and lower than the warm Blob years. Pacific herring, a forage fish, showed both increases and decreases (depending on region within the Sound), while the number of seabirds was similar to or down from recent years (depending on the species). A fall survey showed some of the lowest abundances of marine mammals on record, and apex predator Southern Resident killer whales continued their population decline, apparently related in part to lack of food.

View the full report (external link)