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Presenters Notified: November 2012

Program Schedule Posted:November 2012

Abstracts Available: January 2013

Meeting:
17-22 February 2013

Benitez-Nelson, C., University of South Carolina, USA, cbnelson@geol.sc.edu
Anderson, C. R., University of California Santa Cruz, USA, clrander@ucsc.edu
Thunell R., University of South Carolina, USA, thunell@geol.sc.edu
Sekula-Wood, E., University of South Carolina, USA
Siegel, D., University of California Santa Barbara, USA, davey@eri.ucsb.edu

INCREASING PSEUDO-NITZSCHIA ABUNDANCE AND DOMOIC ACID TOXICITY OF SINKING PARTICLES IN THE SANTA BARBARA BASIN ASSOCIATED WITH CHANGES IN SOURCE WATERS

Since the early to mid 1990’s, the Santa Barbara Basin (SBB) has been the site of intensive time-series water column sampling and sediment trapping. Chlorophyll concentrations have increased significantly over the past several years, consistent with observations of more intense diatom blooms during the spring and summer and fewer, large dinoflagellate blooms beginning in 2001. Sediment trap fluxes confirm these changes with evidence of an abrupt shift upwards in bloom frequency and abundance of the neurotoxin (domoic acid) producing, lightly silicified diatom, Pseudo-nitzschia beginning in 2000. We hypothesize that these shifts are exacerbated by increasing nutrient concentrations in SBB surface waters coupled with a decrease in Si/N and an increase in N/P. Such changes explain the seeming discrepancy between increasing diatom abundance and the transition to less silicified diatom species. Furthermore, silicate and phosphate limitation, combined with increasing acidity, have been shown to facilitate domoic acid production. Given the limited evidence for changes in upwelling in the SBB, we hypothesize that increasing HABs are due to changes in the upwelled properties of the source waters.

Oral presentation

Session #:SS44
Date: 2/20/2013
Time: 11:30