Impact of coastal melt waters on Antarctic phytoplankton

HERNANDO M.; SCHLOSS I.; MALANGA G.; PUNTARULO S.; HOFFMEYER M.; FERREYRA G.

Buenos Aires

Conferencia; Scientific Committee on Antarctic Research (SCAR) XXXI & Open Science Conference; 2010

IMPACT OF COASTAL MELT-WATERS ON THE ANTARCTIC PHYTOPLANKTON Hernando, M.1, Schloss, I.2,3, Malanga, G.4,5, Puntarulo S.4,5, Hoffmeyer, M.6 and Ferreyra, G.2,3 1. Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Bs. As, Argentina 2. Institut de Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Canada, 3.Instituto Antártico Argentino, Bs As, Argentina-4- CONICET, 5. Fisicoquímica-PRALIB, FFyB, UBA, 6. Instituto Argentino de Oceanografía (IADO-CONICET), Bahía Blanca, Bs. As, Argentina. mphernando09@hotmail.com Keywords: melt water, Antarctic phytoplankton, oxidative stress Environmental  change  region  includes local water warming and salinity changes which might impact marine phytoplankton physiology and cause  increased oxidative stress and cellular damage. The aim of the present study was to  assess oxidative stress effects on phytoplankton in Potter Cove, King-George Island (62°14´S, 58°38´W) during a bloom   and the post bloom period (pbp)January- February 2010. Two   areas were studied, with high and low glacier influence   in two depths, above and below the pycnocline. Experiments involved natural phytoplankton communities and isolated cultures (Thalassiosira sp. and picoplankton species). During January an exceptional diatom-dominated phytoplankton bloom (BP) was observed. ANOVA between BP and PBP showed significantly high concentration of ROS during the PBP for both sites and depths?. Significantly higher (highest) respiration rates were observed during the BP (95.78 vs 20.91 mg.O2L-1.h-1) above the  pycnocline near the glacier higher than what??? . Higher photosynthesis values were observed during BP far from glacier influence for both depths (102.85 and 91.25 mg.L-1.h-1 below the pycnocline). Low respiration and photosynthesis above  the  pycnocline near the melting glacier area could be indicative of cellular damage by osmotic stress. Furthermore, picoplankton cultures showed a significantly lower concentration of ROS (0.06 UA.ug Chl-1h-1) and lower respiration (11.48 mg.L-1.h-1) than Thalassiosira sp. (0.14 UA.ug Chl-1h-1 and 24.07 mg.L-1.h-1 for ROS and respiration respectively) for lower salinity, independent of PAR doses received. Our results indicate that salinity might indeed be a factor affecting coastal areas primary production, the trophic web and hence the carbon cycle as well as oxidative stress generation.