Meanders in the Antarctic Polar Frontal Zone and their impact on phytoplankton

• Published in: Deep-sea research. Part II, Topical studies in oceanography Topical studies in oceanography, 2001, Vol.48 (19), p.3891-3912
• Main Authors: Abbott, Mark R., Richman, James G., Nahorniak, Jasmine S., Barksdale, Brett S.
• Format: Article
• Language: English
• Subjects: Algae
• ISSN: 0967-0645; 1879-0100
• DOI: 10.1016/S0967-0645(01)00073-X

The Antarctic Polar Front is a complex set of meandering jets, which appear to support enhanced primary productivity. The US Joint Global Ocean Flux Study conducted a series of survey and process studies in part to study the processes regulating primary productivity in this high nutrient, low chlorophyll region. We deployed a set of surface velocity drifters, some of which were equipped with bio-optical sensors, to study the temporal and spatial scales of biological and physical processes in the Antarctic Polar Frontal Zone. There were two primary sets of deployments: November 1997 before the spring bloom and January 1998 after the spring bloom. The November deployment revealed a strong spring bloom that lasted about 10 days. In late spring, when incoming solar radiation began to increase, the vertical motions associated with the meanders strongly affected the accumulation of phytoplankton biomass, primarily through their impact on light availability. Weaker meandering was observed in the January deployment, and chlorophyll values remained relatively constant. As the bloom began to decay, it appears that nutrient availability became more important in regulating phytoplankton photosynthesis. Some of the drifters in the November deployment were deployed in coherent clusters, thus allowing us to calculate vertical velocities associated with the meanders. Estimates of fluorescence/chlorophyll suggest that areas of upwelling and downwelling alternately decrease and increase photosynthetic stress, perhaps as a result of changes in the availability of iron or light during the formation of the bloom.