Gulf of Alaska | Ecosystem Perspectives MASTER’S POSTER PRESENTATION Investigating impacts of Alaskan shellfish and finfish mariculture on benthic ecosystems Presenter: Jonah Jossart , jrjossart@alaska.edu, University of Alaska, Fairbanks Shellfish and seaweed cultivation constitute a rapidly growing proportion of global mariculture, and Alaska’s extensive coastline and productive nutrient-rich waters have the potential to support competitive commercial mariculture operations for shellfish and salmon. In Kachemak Bay, where there are several proposed mariculture expansions, members of environmental groups such as the Kachemak Bay Conservation Society have expressed concerns about potential harm to the marine environment, upon which local residents depend for subsistence, livelihood, and recreational use. Due to their depositional nature, soft-sediment benthic ecosystems act as a natural lens through which to examine the influence of suspended mariculture facilities on the local environment. Sediment communities are largely composed of non-motile organisms that feed on organic matter sinking from above, and thus tend to reflect average conditions, integrating over short-term sources of variation such as tidal signals, pulses of primary production, and changes in freshwater runoff. Mariculture operations have the potential to impact this environment primarily through organic matter enrichment from the sinking of feces and other organic detritus. This project seeks to investigate potential impacts of shellfish and finfish mariculture in Kachemak Bay on local benthic ecosystems. This work is being done by quantifying the effects of suspended mariculture activities on oxygen and nutrient fluxes between sediments and the water column (dissolved inorganic carbon, phosphate, nitrate), and on biomass and community structure of sediment microbes and macrofaunal invertebrates. Sediment cores have been collected from three bays within Kachemak Bay and Cook Inlet, representing conditions below oyster farms in Jakolof Bay, the salmon hatchery in Tutka Bay, and an unimpacted site in Seldovia Bay. By the end of this project we will have a better understanding of how local mariculture operations affect the benthic ecosystem and how this impact differs between mariculture types.
Alaska Marine Science Symposium 2023 155
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