A recent report by the Center for Coastal Monitoring and Assessement presents a baseline environmental characterization of the inner Kachemak Bay, Alaska. It conducted using standardized National Status and Trends Bioeffects Program methods. Three sites near the village of Port Graham were also sampled for comparison. Concentrations of over 120 organic and metallic contaminants were analyzed. Ambient toxicity was assessed using two bioassays. A detailed benthic community condition assessment was performed. Habitat parameters (e.g. depth, salinity, temperature, dissolved oxygen, sediment grain size, and organic carbon content) that influence species and contaminant distribution were also measured at each sampling site.
The goal of this project was to assess habitat conditions that influence biodiversity and distribution of soft bottom benthic infaunal communities in the northern half of Kachemak Bay, a relatively poorly studied habitat in the Bay. This project characterizes:
- physicochemical sediment properties
- benthic infaunal community distributions and condition
- sediment contaminant concentrations
|1. Study area
||2. The sediment quality triad (SQT) approach
||3. Sampling offshore
A baseline environmental characterization of the inner Kachemak Bay, Alaska was conducted using the sediment quality triad approach based on sediment chemistry, sediment toxicity, and benthic invertebrate community structure. Three sites near the village of Port Graham, and two sites in the footprint of a proposed Homer Harbor expansion, were also sampled for comparison. Concentrations of over 120 organic and metallic contaminants were analyzed. Ambient toxicity was assessed using two amphipod bioassays. A detailed benthic community condition assessment was performed. These bioeffects studies contribute to NOAA’s ecosystem goals to protect, restore, and manage the use of coastal and ocean resources, to assess pollution impacts in the coastal zone, and provide baseline information for assessment of climate change.
Organic compounds were detected throughout the bay but at relatively low concentrations. Homer Harbor sites were shown to have elevated concentrations that were five to ten times higher than in the open bay sites. There was no evidence of residual PAHs attributable to oil spills, outside of local input, beyond the confines of the harbor. Specific benthic community assemblages were distributed based on depth and water clarity. The eastern portion of the bay is stressed by the sediment load from glacial meltwater. Significant toxicity was virtually absent. The benthic fauna at Port Graham contained a significant number of species not found in Kachemak Bay. Contaminant conditions were variable depending on specific location, probably due to local geology and water circulation patterns. PAHs and PCBs were accumulating at a site just south of the Village.
Additional studies have begun that build on this effort, including ongoing efforts to assess the entire Cook Inlet in collaboration with The Cook Inlet Regional Citizens Advisory Council. In 2009, a sampling program was initiated, in collaboration with the Alaska Dept. of Environmental Conservation, to assess the contaminant levels and benthic communities in the bays and harbors of the Kenai Peninsula on the south side of Kachemak Bay.
Products & Services
Data used in the report are available at http://www.ccma.nos.noaa.gov/about/coast/nsandt/download.aspx
Completed, September 2009
For More Information
S. Ian Hartwell, Ph.D.
NOAA/National Status and Trends Program
1305 East West Hwy. (SSMC4, N/SCI-1)
Silver Spring, MD 20910