Estimating growth, loss and potential carbon sequestration of farmed kelp: a case study of Saccharina latissima at Strangford Lough, Northern Ireland

Abstract

Many governments are evaluating marine carbon sequestration processes for their capacity to mitigate the adverse impacts of climate change. This includes the cultivation of macroalgae to sequester carbon dioxide from the atmosphere, which requires accurate estimates from the field. This study estimated the potential rates of carbon sequestration of cultivated macroalgae by quantifying the amount of biomass released into the environment from a kelp, Saccharina latissima, farm in Strangford Lough, Northern Ireland (54.4° N, 5.58° W). We estimated that a mean of 41% of net primary productivity (NPP) of the cultivated kelp was lost prior to harvest following blade fall-off, equivalent to a mean of 7.4 kg of carbon sequestered per 100 m longline at the site during the cultivation period. Coarse estimates requiring verification predicted that a further 43.2% of NPP may have been lost through chronic erosion and exudation of organic carbon. This rate of sequestration is similar to that of several government-funded agroforestry schemes. There is potential, therefore, that this quantified ecosystem service could be subsidized to incentivize the sustainable development of the macroalgae industry. These findings are essential for those promoting the sustainable development of the macroalgae cultivation industry and are highly relevant for implementation of UN Sustainable Development Goal 13 (Climate action) and Goal 14 (Life below water: “Conserve and sustainably use the oceans, seas and marine resources for sustainable development”).

Keywords

• Carbon
• cultivated
• kelp
• macroalgae
• Saccharina latissima
• sequestration