PROJECT

Mariculture Research and Restoration Consortium: Mariculture and the Physicochemical Environment 

Background

The growing concentration of carbon dioxide (CO₂) in the atmosphere is the single greatest environmental issue of the present day. Even with a rapid acceleration of mitigation efforts in the next century, global surface temperature is still predicted to rise by at least 1.5 °C. Blue carbon, which is the removal of CO₂ from the atmosphere through marine primary productivity, is presently an area of intense interest and has shown promise as a sustainable alternative for capturing carbon through enhanced photosynthesis. The kelp farming industry in Alaska expects to expand dramatically in the next two decades, increasing sustainable economic practices in the state with the added benefit of capturing atmospheric CO₂. It is possible that the addition of farmed kelp during periods of localized heterotrophy may result in net autotrophy. We are actively measuring the air-sea CO₂ flux within three kelp farms spanning the Gulf of Alaska to determine the capacity of farmed kelp to reduce atmospheric CO₂ through air-sea flux.

Methods

We deployed a package of sensors at three farms across the Gulf of Alaska: Spinnaker Sea Farms in Jakolof Bay (Kachemak Bay), Alaska Ocean Farms in Kalsin Bay (Kodiak), and Royal Ocean Kelp Co. in Windy Bay (Prince William Sound). One sensor package was placed inside the farm and another upstream of the farm to estimate the net CO₂ air-sea flux at the farm. These sensors will take hourly measurements of temperature, salinity, oxygen, and pH or pCO₂ over three kelp farm seasons and these time series will be converted to air-sea CO₂ flux. We will also determine the drivers of that flux regionally by correlating our measured environmental variables to net CO₂ flux.

What We Will Learn

This project will estimate the net CO₂ flux at three farms across the Gulf of Alaska, as well as provide time series of carbonate system measurements that are typically overlooked in water quality monitoring due to the associated expense and technical know-how.