The Northern California Current on fire: consequences of a widespread and persistent anomalous pyrosome bloom

Data and Code repository for the manuscript titled "The Northern California Current on fire: consequences of a widespread and persistent anomalous pyrosome bloom". Please see the README file for more information. Abstract: Marine heatwaves (MHWs) have increased in intensity and duration globally as a result ofsustained carbon emissions. The North Pacific Ocean witnessed multiple strong and prolongedMHWs since 2014 leading to many ecosystem anomalies. Pelagic urochordates (salps andappendicularians) are dominant components of oceanic, low productivity waters globally andhave been studied with some regularity in temperate ecosystems. However, colonial pyrosomesare generally restricted to oceanic tropical seas and have been far less studied than otherurochordate taxa. The subtropical cosmopolitan species, Pyrosoma atlanticum, also called “firebodies’ due to their bioluminescence, has periodically been sampled from the Northeast PacificOcean off Southern California. With the advent of anomalously warm conditions due to thesevere 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 dominantcomponent of pelagic surveys by 2017. These massive blooms impaired commercial fisheriesand contaminated beaches, prompting public concerns. Due to the paucity of information on thisspecies north of its normal range, we compiled existing and new data on broadscale 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 on thepelagic and benthic food webs and human utilization of this system. Since this tropical invadermay become established in the productive coastal ecosystem of the NCC with predicted futurewarming of the North Pacific, understanding its ecology and potential impacts will fill criticalgaps in our knowledge of the importance of this hitherto understudied species.