REVISITING SEAWEED AQUACULTURE FOR POLLUTION REMEDIATION

A growing human population coupled with climate change is exacerbating the spread and impact from organic matter over-enrichment (eutrophication)

. Despite promising techniques and tools, our current actions are proving insufficient. This mounting issue requires accounting for multiple stressors

, including nutrient loading. Adequate management of nutrient loading requires a holistic set of proven tools that prevent both point source and non-point source pollution, and mitigate eutrophied areas. In this study, we map seaweed aquaculture's potential nutrient uptake in highly impacted estuarine environments. Using the Gulf of Mexico as a case study, we go one step further to make a business case for seaweed aquaculture as an additional mitigation tool.

Seaweed aquaculture has long been proposed as an additional nutrient pollution mitigation tool, but implementation has been stymied by a lack of market access, technology, and political will. However, increasing global demand for seaweed

, recent advancements in open-ocean farming techniques, and efforts to streamline permitting

, provide a new opportunity to simultaneously maximize financial and ecosystem benefits of seaweed aquaculture through strategic spat ial planning around eutrophied areas.

In our  preliminary analysis adapting values from Xiao et al., 2017

, we projected the N and P uptake from farming the Gulf of Mexico. If we were to farm 5% of the Gulf of Mexico's 2019 dead zone

, 435 km², up to 558 tDW seaweed could be produced, removing 20 tN km ^-2  yr^-1 and 2.64 tP km^-2 yr^-1 . One step further, using the Connecticut  Nitrogen Trading Program as an example, this amount of N could result in $225,300 t km^-2 yr^-1 of sales for the estimated N removal

. While these calculations are a best case scenario, seaweed aquaculture offers a promising method of subsidizing nutrient mitigation.