Presentation Abstract

Hypoxia is a regular, yet increasingly prevalent feature of southern regions of Hood Canal, WA. While occasional fish kill events garner much public attention, these events are rare and may therefore may not be as important as effects from non-lethal levels of dissolved oxygen. Low levels (near 2 mg / l ) are common and species have a range of responses Here I use results from multiple investigations to illustrate the nature and magnitude of effects. On a population level, long lived sessile species like geoduck clams show clear evidence of substantial impacts from hypoxia. In addition, several sessile invertebrate species are locally impacted. In contrast, mobile demersal fish and invertebrates show a behavioral response to periods of low dissolved oxygen but these are temporary. We also find that valuable species such as Dungeness crab shoal in nearshore habitats where they are vulnerable to recreational fishing gear. We find that effects at the food web level are unclear. Specifically, euphausiids play a key role in the food web, yet show little evidence of density or distributional response. However, detailed tracking of planktivorous fish feeding and distribution suggests that low dissolved oxygen might tighten trophic connectivity between these two species. Notably, this occurs despite levels of dissolved oxygen that are physiologically stressful. Future work should focus more on ecological consequences of localized depletion and behavioral responses to low dissolved oxygen

Session Title

Interdisciplinary Approaches to Understanding Eutrophication and Over-enrichment of Nutrients in Puget Sound and Effects on Marine Species

Keywords

Hypoxia, Ecosystem

Conference Track

SSE16: Long-Term Monitoring of Salish Sea Ecosystems

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE16-160

Start Date

6-4-2018 9:30 AM

End Date

6-4-2018 9:45 AM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 6th, 9:30 AM Apr 6th, 9:45 AM

Population, community and food web impacts of hypoxia : a synthesis of findings from Hood Canal

Hypoxia is a regular, yet increasingly prevalent feature of southern regions of Hood Canal, WA. While occasional fish kill events garner much public attention, these events are rare and may therefore may not be as important as effects from non-lethal levels of dissolved oxygen. Low levels (near 2 mg / l ) are common and species have a range of responses Here I use results from multiple investigations to illustrate the nature and magnitude of effects. On a population level, long lived sessile species like geoduck clams show clear evidence of substantial impacts from hypoxia. In addition, several sessile invertebrate species are locally impacted. In contrast, mobile demersal fish and invertebrates show a behavioral response to periods of low dissolved oxygen but these are temporary. We also find that valuable species such as Dungeness crab shoal in nearshore habitats where they are vulnerable to recreational fishing gear. We find that effects at the food web level are unclear. Specifically, euphausiids play a key role in the food web, yet show little evidence of density or distributional response. However, detailed tracking of planktivorous fish feeding and distribution suggests that low dissolved oxygen might tighten trophic connectivity between these two species. Notably, this occurs despite levels of dissolved oxygen that are physiologically stressful. Future work should focus more on ecological consequences of localized depletion and behavioral responses to low dissolved oxygen