Succession of benthic marine algae in newly ice-free areas of Potter Cove, Antarctica: a four years study

DOLORES DEREGIBUS; GABRIELA LAURA CAMPANA; KATHARINA ZACHER; CHRISTIAN WIENCKE; MARIA LILIANA QUARTINO

Auckland

Conferencia; XXXIII SCAR Open Science Conference; 2014

XXXIII SCAR Open Science Conference

Global warming at the Western Antarctic Peninsula is very high, leading to a massive retreat of the glaciers. In Potter Cove, King George Island, newly ice-free areas appeared due to glacial retreat opening new space for benthic colonization. This study is the first intend to follow the succession of benthic marine algae in two newly ice-free areas (A1 and A2) during four years (2010 to 2014). For this reason a total of 46 artificial tiles were installed in both areas during April 2010 at 5 m depth. Total algal cover and biomass were analyzed in a central square of 16 x 16 cm in five randomly sampled tiles during four summers in each area. Underwater photosynthetically active radiation (PAR, 400-700 nm) was measured weekly around noon during summer months (January to February). A1 was ice free since 1990 and A2 since 2003 approximately. The light attenuation coefficient, Kd was high during summer indicating strong sediment inflow, and significantly higher in A2 compared to A1. In addition, Kd in A2 was significantly higher in 2012 compared to the rest of the years and similar for A1 among the studied years. During the first year tiles were colonized by benthic diatoms followed by few macroalgal species such as Palmaria decipiens and Monostroma hariotii. The following year?s tiles were rapidly colonized by the brown algae Adenocystis utricularis and red crustose Corallinaceae and by Desmarestia menziesii and Urospora penicilliformis during the last two years of the experiment. Total cover and biomass were not significantly different between areas. Biomass did not increase significantly with time over the four years of the experimental period but the total cover was significantly higher in 2013 compared to the other years. In 2013 temperatures were lower during the summer than in the other years, resulting in a lower inflow of melt water from the glacier into the cove, and consequently a higher light penetration into the water column. The study showed that on the one hand retreating glaciers can open new space for macroalgal colonization, but on the other hand a high sediment run-off from the melting glaciers may affect algal settlement and growth. However, further analysis and comparative studies are needed to understand and predict the possible consequences of rapid environmental changes on algal colonization and succession patterns in Antarctica.