Abstract Title

Session S-06C: Water Quality III

Proposed Abstract Title

Water Properties in Quartermaster Harbor Puget Sound

Keywords

Water Quality

Location

Room 6C

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Description

Over the past six years, researchers at the University of Washington Tacoma (UWT) have studied the hydrographic conditions in Quartermaster Harbor (QMH), a shallow, southward facing bay in central Puget Sound. The initial part of this study was funded by the Russell Family Foundation and then in 2008, EPA Region 10 awarded King County, UWT and Washington State Department of Ecology a West Coast Estuaries Initiative (WEI) grant to conduct a four-year Quartermaster Harbor Nitrogen Management Study. The impetus for studying QMH was twofold, in 2005 a NOAA/ECOHAB study found that the surface sediments in QMH contained the highest concentration of Alexandrium catenella cysts in Puget Sound and QMH has consistently been listed as a water body of concern by the Washington State Department of Ecology for its late summer high temperatures and low oxygen levels. Alexandrium catenella is a dinoflagellate that produces saxitoxin, a powerful neurotoxin, that through shellfish filter feeding can bioaccumulate in bivalves. Ingestion of shellfish containing saxitoxin by humans can result in Paralytic Shellfish Poisoning (PSP) and potentially death. QMH water properties and the phytoplankton community were sampled monthly 2007-2012 to determine why Quartermaster Harbor contained such favorable environmental conditions for Alexandrium catenella, and what parameters affected dissolved oxygen in the bay. Results indicate that oxygen in the inner harbor is a function of both physical and biological forcing conditions. The geographic configuration of the bay impedes flushing and strong stratification in late summer limits vertical mixing. Both of these mechanisms act to limit ventilation and along with biological processes lead to low oxygen levels in late summer in the inner bay. During spring phytoplankton blooms, oxygen levels in the surface water of the inner bay can be extremely high due to photosynthesis. When these organisms die and sink to the bottom, microbial activity decomposes the algae leading to decreased levels of oxygen in the lower water column. Dissolved oxygen, phytoplankton, and nutrient levels are linked in a seasonal pattern which is then intensified by the geographical configuration of the bay to create conditions optimal for high concentrations of Alexandrium catenella and low oxygen levels in the later summer.

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

Water Properties in Quartermaster Harbor Puget Sound

Room 6C

Over the past six years, researchers at the University of Washington Tacoma (UWT) have studied the hydrographic conditions in Quartermaster Harbor (QMH), a shallow, southward facing bay in central Puget Sound. The initial part of this study was funded by the Russell Family Foundation and then in 2008, EPA Region 10 awarded King County, UWT and Washington State Department of Ecology a West Coast Estuaries Initiative (WEI) grant to conduct a four-year Quartermaster Harbor Nitrogen Management Study. The impetus for studying QMH was twofold, in 2005 a NOAA/ECOHAB study found that the surface sediments in QMH contained the highest concentration of Alexandrium catenella cysts in Puget Sound and QMH has consistently been listed as a water body of concern by the Washington State Department of Ecology for its late summer high temperatures and low oxygen levels. Alexandrium catenella is a dinoflagellate that produces saxitoxin, a powerful neurotoxin, that through shellfish filter feeding can bioaccumulate in bivalves. Ingestion of shellfish containing saxitoxin by humans can result in Paralytic Shellfish Poisoning (PSP) and potentially death. QMH water properties and the phytoplankton community were sampled monthly 2007-2012 to determine why Quartermaster Harbor contained such favorable environmental conditions for Alexandrium catenella, and what parameters affected dissolved oxygen in the bay. Results indicate that oxygen in the inner harbor is a function of both physical and biological forcing conditions. The geographic configuration of the bay impedes flushing and strong stratification in late summer limits vertical mixing. Both of these mechanisms act to limit ventilation and along with biological processes lead to low oxygen levels in late summer in the inner bay. During spring phytoplankton blooms, oxygen levels in the surface water of the inner bay can be extremely high due to photosynthesis. When these organisms die and sink to the bottom, microbial activity decomposes the algae leading to decreased levels of oxygen in the lower water column. Dissolved oxygen, phytoplankton, and nutrient levels are linked in a seasonal pattern which is then intensified by the geographical configuration of the bay to create conditions optimal for high concentrations of Alexandrium catenella and low oxygen levels in the later summer.