Valuing carbon sequestration by Antarctic krill faecal pellets

Abstract

AbstractMarine life contribute to carbon stores helping lock carbon away from the atmosphere. Open-ocean pelagic ecosystems are vastly under-reported in terms of carbon sequestration conservation potential, compared to coastal vegetation ‘blue carbon’ systems. Here we show that a harvested organism, Antarctic krill, has similar carbon sequestration potential through its sinking faecal pellets as coastal blue carbon stores, namely seagrasses, mangroves and marshes. Building upon recent advances in krill abundance and faecal pellet carbon flux data, and combining these with an ocean circulation model, we show that from Austral spring to early autumn Antarctic krill sequester 20 Mt C into the deep ocean for at least 100 years. This equates to USD$ 4 - 46 billion per spring/summer season depending on the price of carbon. The footprint of remineralised krill pellet carbon has a global extent, with some reaching as far as the North Pacific. The vast area of ocean krill inhabit and their high abundance make their total carbon sequestered each year similar to that from coastal vegetated blue carbon stores. As Antarctic krill are being impacted by rapid polar climate change and they are harvested, both krill populations and their habitat warrant protection to preserve this valuable carbon sink.