Seasonal and regional variability of phytoplankton blooms in the Scotia Sea – applying SeaWiFS satellite imagery to the Southwest sector of the Atlantic Ocean.

• Main Authors: Borrione, Ines, Schlitzer, Reiner
• Format: Conference Object
• Language: unknown
• Published: 2010
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarctic Peninsula; Drake Passage; Scotia Sea; Sandwich Islands; South Sandwich Islands; South Georgia; South Scotia Ridge; Antarc*; Sea ice
• Online Access: https://epic.awi.de/id/eprint/33778/; https://hdl.handle.net/10013/epic.42118

The islands of the Southern Ocean, the largest of the High Nutrient Low Chlorophyll (HNLC) regions, have an important role in favouring phytoplankton growth and bloom development. Concentrations of iron, which has been demonstrated to be an important limiting micronutrient, play a major role in regulating the intensity and location of these blooms; however, sea-ice melting, ocean circulation patterns and the “island mass effect” may as well help explain such striking events for a HNLC region. This study will focus on the Southwest sector of the Atlantic Ocean, specifically on the Scotia Sea; this region [52°W – 30°W; 48°S – 56°S] is included between the North and South Scotia Ridge, and between the Drake Passage and the South Sandwich Islands. The main coastal ecosystems are those of the South Georgia, South Orkney and the South Sandwich islands; also the Antarctic Peninsula is included in the domain. The natural dynamics of phytoplankton blooms in the Scotia Sea have been investigated by analysing SeaWiFS, 9km resolution monthly composites of chlorophyll-a concentrations. The retrieved 12-year satellite time series (1997-2009) shows a clear seasonal trend in chlorophyll concentrations, which start increasing in August. Maximum concentrations (> 3 mg/m^3) are detected between December and January after which bloom regions start shrinking in size, and chlorophyll-a concentrations return to the winter background concentrations. In this presentation we will also show how circulation patterns, bathymetry, continental shelves as well as the Antarctic Circumpolar Fronts are the major factors controlling the extension and location of these highly productive patches. The complexity of interactions between phytoplankton communities and the surrounding environment implies the need for more dedicated surveys and high resolution coupled physical-biogeochemical models; the latter would provide further information regarding nutrient fluxes and physical processes, especially during the under-sampled winter season, and in the deeper layers not captured by satellite images.