Optical tagging and tracking of water masses for prediction of human health hazards

Pete StruttonCollege of Oceanic and Atmospheric Sciences

Oregon State University

Michelle Wood, Brittany Scott and Andy Ohana-RichardsonDepartment of Biology, University of Oregon

Background and General Approach

• Increasing frequency and persistence of HABs– Anthropogenic impacts, climatic shifts, ballast water dispersal

• Monitoring programs exist, but are not pro-active• Off Oregon the main toxic species are:

– Pseudo-nitzschia, diatom, produces Domoic Acid, leads to Amnesic Shellfish Poisoning

– Alexandrium, dinoflagellate, produces saxitoxin, leads to Paralytic Shellfish Poisoning

• Some HAB species (notably K. brevis) have unique optical signatures that can be used to detect in situ or from space.

• Goal: Use (multiple) satellite products to predict and track HABs

Historical data from the Oregon Dept of Agriculture

Large database of coastal toxin concentrations

Both saxitoxin and domoic acid in mussels and razor clams

Most comprehensive from 1998 to present

Includes two large events (1998 and 2005)

Backtrack from coastal observations to offshore conditions

Large domoic acid event in 1998

From: Hickey and Banas, 2003

Observed along the entire west coast

Linked to California Sea Lion deaths, particularly in central CA

Relatively well-sampled with documented hot-spots on Heceta Bank and the Juan de Fuca eddy

Focussed attention on the JdF eddy as a potential incubator

Juan de Fuca eddy: HAB incubator?

From: Sackmann & Perry, in press

Spectral signatures as a tracking tool

From: Sackman & Perry, in press

Heceta Bank: A Juan de Fuca eddy analog?

From: Barth, Pierce and Castelao, 2005

Heceta Bank: A Juan de Fuca eddy analog?

Climatology of chlorophyll and HAB ‘hot spots’

HB

In situ measurements: May 2005 event

HB

Chl [mg m-3]

Domoic acidDomoic acid[nM][nM]

Logistic Regression: Events vs Upwelling

• Logistic regression: An appropriate tool for analyzing a categorical response to continuous physical forcing

• Regress toxin > closure level (or not) vs upwelling dynamics (Bakun upwelling index)

• Performed for saxitoxin (PSP) for 5 sites spanning the OR coast• Determined that closure levels of saxitoxin are often associated

with downwelling conditions - toxin brought close to the coast• By monitoring blooms by satellite and upwelling conditions (local

meteorology) we can better target sampling.• Analysis works poorly for DA (retention) but same principle

Upwelling/Downwelling and Coastal Impacts

~10s km

N P Si Fe

toxic impact

Education and Outreach

• Significant public interest in the project because of the connection to recreational shellfish harvesting

– Press release in 2005 yielded significant coverage• At least 3 Oregon newspapers + OSU and UO university papers• Local TV and radio• Article in NIEHS’ Environmental Health Perspectives

• Two graduate students currently involved• Undergraduate, satellite data processing, summer 2005• High school student and undergraduate involvement for 2006• Short course on HABs at UO’s OIMB, July 2006• Collaboration with CoastWatch: Preliminary products

Accomplishments to date and future work

• Retrospective analysis of Oregon Dept of Agriculture toxin data– Confirms Heceta Bank (and Columbia) as HAB hot spots– Have begun coupling these data with SeaWiFS chlorophyll– Next step: Go beyond chlorophyll to spectral signatures– Include analysis of fronts: both chlorophyll and temperature

• Large-scale event in 2005, with record Domoic Acid concentrations observed onshore

– in situ sampling of this bloom coupled with remote sensing• Established collaborations with WA and CA colleagues

– Strengthen these ties in the interest of standardized methods• Expanded in situ sampling and collaboration with CoastWatch in 2006

Increasing toxicity of Oregon events

Note: 2005 DA concentrations were highest ever observed

Increasing PSP toxicity associated with El Niño

El Niño La Niña

Also some evidence for increasing toxicity at interannual scales

2005: Highest domoic acid concentrations observed

2000, 2001: Highest saxitoxin years on record

Retention of Domoic Acid by Shellfish

Results from Juan de Fuca work

• Transport events from the JdF to the WA coast are frequently observed.

• Delivery of seed populations to the coast by (1) direct advection, (2) switch to downwelling winds, or (3) sinking and upwelling of cells.

• Despite the absence of a clear optical signal for Pseudonitzschia, radiance spectra can be used to track masses.

• Satellite data monitoring could enhance shore-based sampling and management.