Abstract Title

Session S-01D: Pelagic Ecology in the Salish Sea I

Proposed Abstract Title

Physical attributes of nearshore waters across greater Puget Sound, with an emphasis on dissolved oxygen and pH

Keywords

Species and Food Webs

Location

Room 611-612

Start Date

30-4-2014 10:30 AM

End Date

30-4-2014 12:00 PM

Description

The pelagic zone is a major part of the Puget Sound ecosystem that is sensitive to human influences, yet our understanding of relationships among its abiotic features, water quality, biota, and anthropogenic influences in spatial and temporal context is limited. To characterize the pelagic zone in greater detail, we conducted a multi-trophic level assessment that measured over 20 potential indicators of pelagic ecosystem health at 79 sites in six oceanographic basins of Puget Sound from April to October 2011. Among the many strong spatiotemporal patterns observed were basin and seasonal differences in temperature, salinity, and turbidity linked to freshwater influences; and inorganic nutrient concentrations. DO concentrations also followed distinct seasonal patterns within oceanographic basins. Seasonally, the monthly percentage of sites with DO concentrations below the threshold for biological stress of 5 mg L-1 increased from 0% in April to 45% in October. Spatially, DO concentrations below 5 mg L-1 were recorded at sites within all basins with the exception of the Central basin. By October, the proportion of sites with biologically stressful DO concentrations was highest among sites in Rosario (100%), Hood Canal (77%), and Whidbey (75%) basins. A persistent significant positive correlation between DO and pH was observed across Puget Sound. Both the strength (R2) and magnitude (slope) of the relationship increased with depth. This linkage was also observed in independently collected water column profiles by the Washington State Department of Ecology (WDOE) in 2011 over the same geographic extent. Furthermore, a 22-year long WDOE dataset (1990-2011) indicates that the relationship between DO and pH may be a persistent predictable feature in Puget Sound with biological implications, given that biological stress associated with low DO is likely to be accompanied by low pH stress.

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Apr 30th, 10:30 AM Apr 30th, 12:00 PM

Physical attributes of nearshore waters across greater Puget Sound, with an emphasis on dissolved oxygen and pH

Room 611-612

The pelagic zone is a major part of the Puget Sound ecosystem that is sensitive to human influences, yet our understanding of relationships among its abiotic features, water quality, biota, and anthropogenic influences in spatial and temporal context is limited. To characterize the pelagic zone in greater detail, we conducted a multi-trophic level assessment that measured over 20 potential indicators of pelagic ecosystem health at 79 sites in six oceanographic basins of Puget Sound from April to October 2011. Among the many strong spatiotemporal patterns observed were basin and seasonal differences in temperature, salinity, and turbidity linked to freshwater influences; and inorganic nutrient concentrations. DO concentrations also followed distinct seasonal patterns within oceanographic basins. Seasonally, the monthly percentage of sites with DO concentrations below the threshold for biological stress of 5 mg L-1 increased from 0% in April to 45% in October. Spatially, DO concentrations below 5 mg L-1 were recorded at sites within all basins with the exception of the Central basin. By October, the proportion of sites with biologically stressful DO concentrations was highest among sites in Rosario (100%), Hood Canal (77%), and Whidbey (75%) basins. A persistent significant positive correlation between DO and pH was observed across Puget Sound. Both the strength (R2) and magnitude (slope) of the relationship increased with depth. This linkage was also observed in independently collected water column profiles by the Washington State Department of Ecology (WDOE) in 2011 over the same geographic extent. Furthermore, a 22-year long WDOE dataset (1990-2011) indicates that the relationship between DO and pH may be a persistent predictable feature in Puget Sound with biological implications, given that biological stress associated with low DO is likely to be accompanied by low pH stress.