Carbon Balance Under a Changing Light Environment

DEREGIBUS, DOLORES; KATHARINA ZACHER; BARTSCH, INKA; CAMPANA, GABRIELA LAURA; MOMO, FERNANDO R.; CHRISTIAN WIENCKE; GÓMEZ, IVÁN; QUARTINO, MARÍA LILIANA

Antarctic Seaweeds

Springer

Año: 2020; p. 173 - 191

The natural environment of Antarctic seaweeds is characterized bychanging seasonal light conditions. The ability to adapt to this light regime is one ofthe most important prerequisites for their ecological success. Thus, the persistenceof seaweeds depends on their capacity to maintain a positive carbon balance (CB)for buildup of biomass over the course of the year. A positive CB in Antarcticaoccurs only during the ice-free period in spring and summer, when photosyntheticallyactive radiation (PAR, 400?700 nm) penetrates deeply into the water column. The accumulated carbon compounds during this period are stored and remobilized tosupport metabolism for the rest of the year.Over the last decades climate warming has induced a severe glacial retreat inAntarctica and has opened newly ice-free areas. Increased sediment runoff, andreduced light penetration due to melting during the warmer months, may lead to anegative CB with changes in the vertical distribution of seaweeds. Furthermore,warmer winters and springs result in earlier sea-ice melt, causing an abrupt increasein light, compensating the reduction in PAR in summer or increasing the annuallight budget. Studies performed in Potter Cove, Isla 25 de Mayo/King GeorgeIsland, reveal that algae growing in newly ice-free areas did not acclimate to thechanging light conditions. Lower or even negative CB values in areas close to theglacier runoff seem to be primarily dependent on the incoming PAR that finallydetermines the lower distribution limit of seaweeds. The present chapter discusseshow carbon balance respond to the changing Antarctic light environment and itspotential implications for the fate of benthic algal communities.