A phytoplankton bloom and associated processes observed with a long-term moored system in antarctic waters

Abstract

A moored system was designed for monitoring both longand short-term temporal variations in phytoplankton communities. It consisted of a chlorophyll buoy, a current meter and a sequential, multiple-sampling sedment trap, set at depths of 52. 57 and 120 m. respectively. The system was deployed at 7Oo11.54'S, 2418.68'E in Breid Bay, Antarctica, from 28 December 1985 to 13 February 1986. A total of 1127 hourly data sets and 12 trap samples were obtained. Equivalent chlorophyll a concentration fluctuated mainly in the range 0.69 to 5.60 yg 1-l; values tended to decrease toward early February. Tides caused the depth of the buoy to vary between 51 0 and 52.9 m. A strong positive correlation was found between chlorophyll a level and water temperature and indicates a possible advective water movement in the Bay. Vertical flux of particulate pigments showed a marked increase in mid-January, 3.5 to 10.5 d after an increase was observed In surface chlorophyll. Sediment samples were dominated by intact cells of Thalassiosira antarctica throughout the period of observation.