Assessment of CO2 removal potential of Neopyrpia aquaculture beds

Abstract

The global seaweed aquaculture beds (SABs) contribute positively to carbon sequestration. Among the cultivated seaweeds, Neopyropia (or Pyropia) represents about 8% of the global seaweed production and has the capacity to sequester a significant amount of C from the surface layer of the ocean. In this study, we evaluated the potential C removal efficiency of Neopyropia SABs by measuring DO evolution. Neopyropia thallus were collected from Neopyropia SABs on the south and west coasts of Korea from 2016 to 2019 (December to March), and photosynthetic light response curves were measured. The maximum C uptake rates ranged from 3.35 to 5.84 mg C g-1ww h-1, demonstrating a strong availability of carbon sequestration by Neopyropia SABs. To quantify the C uptake potential (i.e., carbon-based primary productivity) in the coastal areas of the Korean peninsula during the cultivation period (December to March), we extrapolated the C uptake rates using the total area of Neopyropia SABs and meteorological irradiance data. The highest C removal potential was observed in the Southern Sea in December with a value of 6,254 kt C month-1. Considering all productivity data from the entire cultivation period, approximately 22,074 kt C were taken up by the Neopyropia SABs. Our study indicates that Neopyropia SABs have a significant potential for C uptake through primary production via photosynthesis. Furthermore, harvesting and effectively utilizing macroalgal primary productivity could contribute to the reduction of greenhouse gas emissions.