Chasing glacial retreat: macroalgal expansion and blue carbon gains in coastal ice-free areas.

DEREGIBUS, DOLORES; BARNES, DAVID K. A.; JEROSCH, KERSTIN; CAMPANA, GABRIELA L.; ZACHER, KATHARINA; QUARTINO, MARÍA LILIANA; NEDER, CAMILA; PISCICELLI, JUAN MANUEL

Conferencia; 10th SCAR Open Science Conference; 2022

The West Antarctic Peninsula (WAP) is a hotspot of physical climate change,including glacial retreat. Along coastlines, this process opens up newly ice-free areas,which can be colonized by benthic organisms. We investigated this process at PotterCove, Isla 25 de Mayo/King George Island, Antarctica. New ice-free areas thereshowed a gradient of sediment run-off and light penetration driven by levels of glacialinfluence. We studied two newly ice-free areas (LGI a low glacier influence area, andHGI a high glacier influence area). We installed artificial substrates (tiles) at 5 m depthto analyze benthic algal colonization and succession for four years. Photosyntheticactive radiation (PAR, 400-700 nm) was monitored at both sites in spring and summer.The light attenuation (K d ) was significantly lower at LGI than HGI. All tiles werecolonized by benthic algae, differing in species identity, richness and successionalpatterns between areas. We scaled up our quadrat surveys on the natural substrate toestimate benthic algal colonization in newly deglaciated areas of the whole Potter Cove.Recent decades have exposed much new habitat, with macroalgae making up animportant part of communities ‘chasing’ such glacier retreat. Our estimation of algalcolonization in newly ice-free areas shows an expansion of ~0.005-0.012 km 2 and acarbon standing stock of mature algal communities of ~0.2-0.4 C tons per year. Lifemoving into a new space in such WAP fjords has the potential to be key for new carbonsinks and export.