TEMPERATURE IMPACTS ON THE ABUNDANCE AND GROWTH RATE OF PSEUDO-NITZSCHIA SPECIES LOCAL TO MONTEREY BAY, CALIFORNIA

Harmful Algae Blooms (HABs) are a global issue that occur when toxic phytoplankton, like species in the pennate diatom genus Pseudo-nitzschia (PN), capitalize on favorable water conditions to form dense physical aggregations. Monterey Bay (MB), California has experienced severe HAB events recently in conjunction with warm sea surface temperature (SST) anomalies One of the most toxic HABs followed the 2015 Pacific Marine Heat Wave (MHW) that warmed MB to over 15°C. Natural processes like El Niño Southern Oscillation (ENSO) events and anthropogenic activities can contribute to similar warming, and models predict a 1-3°C rise in global SSTs. We seek to understand how the abundance of PN species local to MB respond to these temperature increases to better predict HAB threats by establishing growth rate and abundance measures at the current average MB SST, 12°C. We expected both measurements to be greater from P. multiseries than P. pungens, due to its prevalence in prior HABs. This study employed growth rate experiments to compare the two species. We measured species abundance and calculated growth rates from daily cell counts using a Sedgewick Rafter counting chamber. The results support that P. multiseries outperforms P. pungens in abundance and growth rate. Ultimately, HABs threaten to cost coastal communities millions in fisheries closures and pose a hazard to human and marine health. In comparing species at current MB average SSTs, we are establishing a comparison base for future temperature studies and improving HAB monitoring networks and models.

Presentation Preference: Poster

Primary Presenter: Maya Clarke, Florida Atlantic University (mayaclarke2021@fau.edu)

Authors:

Maya Clarke, Florida Atlantic University  (mayaclarke2021@fau.edu)

Hannah McGrath, San Jose State University, Moss Landing Marine Laboratories  (hannah.mcgrath@sjsu.edu)

Holly Bowers, San Jose State University, Moss Landing Marine Laboratories  (holly.bowers@sjsu.edu)