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

DEREGIBUS, DOLORES; CAMPANA, GABRIELA LAURA; NEDER, CAMILA; DAVID DKA BARNES; ZACHER, KATHARINA; JEROSCH, KERSTIN; QUARTINO, MARÍA LILIANA

Vasco da Gama

Congreso; 10TH SCAR OPEN SCIENCE CONFERENCE; 2022

Scientific Committee of Antarctic Research

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 processat the Antarctic coastal ecosystem Potter Cove which showed a gradient of sediment run-off and light penetration drivenby levels of glacial influence. We studied two newly ice-free areas (a low -LGI- and a high -HGI- glacier influence area).Photosynthetic active radiation (PAR, 400-700 nm) was monitored at both sites in spring and summer. The lightattenuation (Kd) was significantly lower at LGI than HGI. We installed artificial substrates (tiles) at 5 m depth to analyzebenthic algal colonization and succession for four years. All tiles were colonized by benthic algae, differing in speciesidentity, richness and successional patterns between areas. We scaled up our quadrat surveys on the natural substrateto estimate benthic algal colonization in newly deglaciated areas of the whole Potter Cove. Recent decades haveexposed much new habitat, with macroalgae making up an important part of communities ‘chasing’ such glacier retreat.Our estimation of algal colonization in newly ice-free areas shows an expansion of ~0.005-0.012 km2 and a carbonstanding stock of mature algal communities of ~0.2-0.4 C tons per year. Life moving into a new space in such WAP fjordshas the potential to be key for new carbon sinks and export.