Abstract Title

Session S-03A: Changes in Salish Sea Water Quality

Proposed Abstract Title

Physical and microbial drivers of hypoxia in Bellingham Bay

Keywords

Marine Water Quality

Location

Room 6C

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Description

Bottom water hypoxia is a feature of many coastal embayments and fjords in the Salish Sea. Ongoing research in Bellingham Bay (Bellingham, WA USA) by Northwest Indian College and Western Washington University has identified a seasonally recurring area of low dissolved oxygen near the center of the bay. Similar to other regions of the Salish Sea, hypoxia in Bellingham Bay may be a naturally occurring phenomenon, yet the extent of eutrophication and anthropogenic nutrient loading’s influence on patterns of hypoxia is poorly understood. The present study has continued an established monitoring program documenting the range, duration and severity of hypoxia in Bellingham Bay, while adding an experimental component investigating factors that regulate respiration of heterotrophic bacterioplankton. Profiles of water column parameters and sample collection were performed on six regularly scheduled cruises. Dissolved oxygen concentrations below the hypoxic threshold were observed in bottom waters in the center of Bellingham Bay for most of the summer, although the layer of hypoxic water appeared to migrate upwards into the water column in late July. Manipulative experiments were conducted on collected water samples to investigate effects of temperature and organic carbon on water column respiration. These experiments revealed that temperature had a negligible effect on water column respiration, while organic carbon stimulated oxygen consumption and was thus identified as a possible limiting factor. The study’s findings broaden our knowledge of factors regulating oxygen dynamics in coastal embayments of the Salish Sea and provide further insight into the potential effects of anthropogenic stressors and climate change on Salish Sea water quality.

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May 1st, 5:00 PM May 1st, 6:30 PM

Physical and microbial drivers of hypoxia in Bellingham Bay

Room 6C

Bottom water hypoxia is a feature of many coastal embayments and fjords in the Salish Sea. Ongoing research in Bellingham Bay (Bellingham, WA USA) by Northwest Indian College and Western Washington University has identified a seasonally recurring area of low dissolved oxygen near the center of the bay. Similar to other regions of the Salish Sea, hypoxia in Bellingham Bay may be a naturally occurring phenomenon, yet the extent of eutrophication and anthropogenic nutrient loading’s influence on patterns of hypoxia is poorly understood. The present study has continued an established monitoring program documenting the range, duration and severity of hypoxia in Bellingham Bay, while adding an experimental component investigating factors that regulate respiration of heterotrophic bacterioplankton. Profiles of water column parameters and sample collection were performed on six regularly scheduled cruises. Dissolved oxygen concentrations below the hypoxic threshold were observed in bottom waters in the center of Bellingham Bay for most of the summer, although the layer of hypoxic water appeared to migrate upwards into the water column in late July. Manipulative experiments were conducted on collected water samples to investigate effects of temperature and organic carbon on water column respiration. These experiments revealed that temperature had a negligible effect on water column respiration, while organic carbon stimulated oxygen consumption and was thus identified as a possible limiting factor. The study’s findings broaden our knowledge of factors regulating oxygen dynamics in coastal embayments of the Salish Sea and provide further insight into the potential effects of anthropogenic stressors and climate change on Salish Sea water quality.