Modeling the krill transport pathways in the Scotia Sea: spatial and environmental connections generating the seasonal distribution of krill

• Published in: Deep Sea Research Part II: Topical Studies in Oceanography
• Main Authors: Murphy, E.J., Thorpe, S.E., Watkins, J.L., Hewitt, R.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2004
• Subjects: Marine Sciences; Glaciology; Biology and Microbiology; Ecology and Environment; Antarctic; The Antarctic; Weddell Sea; Scotia Sea; Sandwich Islands; South Sandwich Islands; Weddell; South Georgia; Antarc*; Antarctic Krill; Euphausia superba; Sea ice
• Online Access: http://nora.nerc.ac.uk/id/eprint/12307/; http://www.sciencedirect.com/science/article/pii/S0967064504000906

A coupled physical-biological model analysis was undertaken to examine the seasonal development of the distribution of antarctic krill (Euphausia superba Dana) in the Scotia Sea. The origin and fate of krill observed during the CCAMLR 2000 survey were studied using output from the OCCAM model. Lagrangian particle tracking for the period prior to the survey showed the expected dominance of the west to east flow of material associated with the main direction of the current flow, but there was no simple association of particle transport with any of the fronts of the Antarctic Circumpolar Current. Most of the krill were associated with areas to the south of the Antarctic Circumpolar Current in the Weddell-Scotia Confluence (WSC) and farther east in Weddell Sea-influenced waters. Examining the pathways of krill transport in relation to satellite-derived sea-ice distributions suggests that particles present in the high krill biomass regions in January would have come from areas that were covered by sea-ice during late winter/early spring (September-October). The results of Eulerian grid-based simulations of the development of the biomass distribution after the survey period showed transport of particles around South Georgia, probably in association with the Southern Antarctic Circumpolar Current Front. However, many of the krill encountered in the eastern Scotia Sea would have exited toward the east, passing north of the South Sandwich Islands, probably in association with the Southern Boundary of the Antarctic Circumpolar Current and Weddell Sea waters that penetrate to the north in this area. These krill may return to more southern regions where further spawning is possible in later years. Simulations of particle tracks that included diurnal vertical migration showed that krill behavior could modify the pathways of transport, although the current flows probably dominate the movement of krill in open ocean regions. This study suggests that the summer distribution of krill in the Scotia Sea is connected to the winter ...