Speaker: Xiuning Du, CIMRS, OSU & NOAA

Topic: The diatom Pseudo-nitzschia (PN) blooms annually in coastal waters of the California Current. Because of anomalously warm ocean conditions in 2015, the U.S. west coast experienced the most persistent, wide-spread and toxic PN bloom on record. PN produced a neurotoxin domoic acid (DA) which marine fauna bioaccumulated from feeding on PN cells and became a human health hazard. For the first time, the most valuable Dungeness crab fishery in Oregon was closed. Since then, the crab fishery opening has been annually delayed and/or closed partially due to the above health concerning level of DA detected in crabs. While we are understanding more about the general seasonality of PN blooms on the OR coast and its nonlinear correlation with DA production, we have also seen that observed surface toxic PN blooms transfer its toxicity effects to Dungeness crabs are very timing/season dependent. There is a range of temporal and spatial opportunities for PN (and DA) reaching crabs in conjunction with local environmental and biological effects. By far, little information about PN cell presence and abundance in the deep water environment on the OR. However, examining the direct availability of toxic PN cells in the nearby environment where crabs live opens up thoughts on mechanisms of DA post-bloom lingering effects on crabs.