Speaker: Richard D. Brodeur Northwest Fisheries Science Center, NOAA, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Hatfield Marine Science Center

Topic: The Northern California Current on Fire: Are Marine Heatwaves and Pyrosome Blooms the New Normal?

Marine heatwaves (MHWs) have increased in intensity and duration globally as a result of sustained carbon emmissions.  The North Pacific Ocean witnessed multiple strong and prolonged MHWs since 2014 leading to many ecosystem anomalies. Pelagic urochordates (salps and appendicularians) are dominant components of oceanic, low productivity waters globally and have been studied with some regularity in temperate ecosystems.  However, colonial pyrosomes are generally restricted to oceanic tropical seas and far less studied.  The subtropical cosmopolitan species, Pyrosoma atlanticum, has priodically been sampled off Southern California.  With the advent of anomalously warm conditions due to the severe MHW in 2014, P. atlanticum started appearing in the Northern California Current (NCC), north of its known range, and following a strong El Niño in 2016, became the dominant component of pelagic surveys by 2017.  These massive blooms impaired commercial fisheries and contanimated beaches, prompting public concerns.  Due to the paucity of information on this species north of its normal range, existing and new data are presented on horizontal and vertical distributions, habitat preferences, feeding ecology and grazing rates, and utilization by higher trophic levels.  This information was assimilated into an end-to-end ecosystem model to examine impacts to the pelagic and benthic food webs and human utilization of this system. Since this tropical invader may become established in the productive coastal ecosystem of the NCC with predicted future warming of the North Pacific, understanding its ecology and potential impacts will fill critical gaps in our knowledge of the importance of this understudied species.