Spatial and temporal trends in the distribution of macronutrients in surface waters of the Drake Passage

• Main Authors: Paparazzo, F.E., Alder, V.A., Schloss, I.R., Bianchi, A., Esteves, J.L.
• Format: Journal/Newspaper
• Language: unknown
• Subjects: Antarctic fronts; Antarctic zones; Chlorophyll-a; Interannual variation; Nitrate; Phosphate; Salinity; Seasonal variation; Silicate; Temperature; annual variation; atmosphere-ocean system; biogeochemistry; chlorophyll a; concentration (composition); El Nino-Southern Oscillation; nutrient dynamics; polar front; temperature effect; Antarctic Circumpolar Current; Atlantic Ocean; Drake Passage; Pacific Ocean; Pacific Ocean (South); Southern Ocean; Antarc*; Antarctic
• Online Access: https://hdl.handle.net/20.500.12110/paper_03275477_v26_n1_p27_Paparazzo

The Drake Passage (DP) links the Southern Pacific and Atlantic Oceans, and acts as a physical narrowing for the largest current of the World Ocean, the Antarctic Circumpolar Current (ACC). This result in a constriction of the main circumpolar fronts related to the ACC: the Subantarctic Front, the Polar Front, the Southern Antarctic Circumpolar Current Front and the Continental Water Boundary Front. Previous studies showed that the DP is a high-nutrient low-chlorophyll (HNLC) region, but studies on the interannual and seasonal macronutrients’ fluctuations in relation with chlorophyll and frontal areas in the DP are scarce. This study analyzes the spatial and temporal trends of nitrate, phosphate, and silicate on surface samples from 113 oceanographic stations in the DP during summer and early fall of 2001 to 2004, in relation with the different fronts and chlorophyll-a concentration. The results revealed an increase of nutrients towards the south. Nitrate showed values from 3 μM at 55° S to 27 μM at 63° S, whereas values from 0.3 μM at 55° S to 2.6 μM at 63° S were observed for phosphate. Silicate increased considerably south of Polar Front, from 0 μM at 55° S to 74 μM at 62° S. The nutrients concentration was significantly higher in summer than in early fall and showed a trend to decrease over the studied years. A complex sum of biogeochemical processes would generate the main seasonal trends, while atmospheric-oceanic processes such as Southern Annular Mode and El Niño Southern Oscillation, would be responsible of observed nutrients interannual variability. © 2016, Asociacion Argentina de Ecologia. All rights reserved. Fil:Paparazzo, F.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Alder, V.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Schloss, I.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.