pH Sensors for Experimental Kelp Farm (Aquaculture)

Two moorings mark the borders of an experimental kelp farm. On the northern edge of Hood Canal, a major basin in Washington State’s Puget Sound, a patch of Saccharina latissima (also known as Sugar Kelp) is helping to identify if seaweed aquaculture can help combat ocean acidification. Started in 2015, this project is primarily funded by a $1.5 million grant from the Paul G. Allen Family Foundation. It is a collaborative effort led by the Puget Sound Restoration Fund in partnership with various collaborators, including the University of Washington and NOAA’s Pacific Marine Environmental Lab.

In theory, the premise is straightforward—kelp such as Saccharina latissima harness carbon dioxide that would otherwise acidify the surrounding water, helping to mitigate the unwanted decreases in pH that result in ocean acidification. Whether this CO2 uptake is enough to reduce acidification on a wider scale, and if the impact of the kelp can affect natural variations in the environment, are the questions that draw interest in the experiment.

The Alpha pH Sensors for Aquaculture

In January 2018, scientists from University of Washington’s Applied Physics Laboratory and Sea-Bird Scientific installed the very first Deep SeapHOx V2s on the aquaculture plot’s two moorings. These were pre-release “alpha” test versions that had produced promising results in a test bath. In a previous life, these two Deep SeapHOxes were once SeaFET V1s: when Sea-Bird Scientific made the decision to upgrade the line of ISFET pH sensors to the SeaFET V2, these units were readily available for upgrades. Thus, serial numbers 001 and 002 were born.