Cascadia Simulations
PNWTOX - Pacific NorthWest TOXins project

summary

2005 Surface conditions

A movie throughout 2005 showing subtidal (i.e. low passed to remove the tidal signal) a) Near surface salinity (psu) and b) near surface temperature (degrees C). The right panels show the forcing conditions including c) Along-coast wind stress, T_maj (black, Nm^-2) and an 8 day weighted upwelling index, W (gray, 10^-2m²s^-1) (Austin & Barth 2002) at the station indicated with a star in panel a, d) River flow (10³m³s^-1) for the Columbia (black) and Fraser (gray) rivers, and e) sea surface height (m) tidal (gray) and rms tidal elevation (black).

The PNWTOX project, led by Barbara Hickey, is designed to investigate and improve predictability of the arrival of harmful algal blooms (HABs) on Washington and Oregon beaches from known HAB hot spots. The project is jointly funded by the National Oceanic and Atmospheric Administration's National Centers for Coastal Ocean Science and the National Science Foundation and is an extension of two recent projects, the Ecology and Oceanography of Harmful Algal Blooms in the Pacific Northwest (ECOHAB PNW) and River Influences on Shelf Ecosystems (RISE). Results from the prior studies suggest that lack of understanding of the effects of the freshwater plume originating from the Columbia River on circulation pathways and mixing is the greatest impediment to understanding how HABs arrive at the coast. Thus the PNWTOX project specifically addresses the role of the Columbia plume in HAB transport to the PNW coastline.

Previous research has identified HAB hot spots as well as a few transport pathways from these regions to the PNW coastline. Two important HAB hot spots where observations consistently show high phytoplankton biomass and HABs due to retention include the Juan de Fuca eddy region (located offshore of the Straight of Juan de Fuca, N. Washington) and Heceta Bank (offshore of central Oregon). MacFayden et al. (2005) have identified a transport pathway between the Juan de Fuca Eddy region and the WA coast in which a series of wind events allow for high eddy retention (downwelling winds), followed by escape from the eddy (upwelling), and then Ekman transport towards the shore (downwelling). Similarly Hickey et al. (accepted, Harmful Algae) have observed that Heceta Bank can be a source region for WA coast blooms during downwelling winds. However, actual toxic events are rare and we expect that the Columbia River plume may play a role in influencing these transport pathways. Banas et al. (2009) found that in the nearshore region of the CR plume, the plume acts as a barrier to shore-ward transport and along-shore transport. The PNWTOX project aims to confirm these transport pathways to the coast, identify additional transport pathways, and test if the observations of the influence of the CR in the near-plume region hold true on a larger scale.

The project focuses on the toxigenic Pseudo-nitzschia, a diatom that can produce domoic acid, resulting in Amnesic Shellfish Poisoning when ingested, as well as other species of HABs for which more limited data are available. By further understanding these transport pathways, we will improve HAB forecasting ability so that harvest closures for razor clams, other shellfish and Dungeness crabs can be minimized.

This website focusses on results from the University of Washington Coastal Modeling Group (UW CMG) hydrodynamic numerical simulations, see the main PNWTOX site for additional information regarding other aspects of the PNWTOX project. These simulations are part of a series of Cascadia simulations run by the UW CMG. This website also includes some information on other projects associated with the PNWTOX project Cascadia simulations including the addition of dissolved oxygen to the model to examine hypoxia and ocean acidification (SA Siedlecki, funded by JISAO), and a project investigating ocean/estuarine connectivity (SN Giddings, funded by NSF).