Temporal changes in marine environments in the Antarctic Peninsula area during the 1994/95 austral summer
To reveal the temporal changes in Antarctic marine environments during the 1994/95 austral summer, oceanographic surveys were carried out in the Antarctic Peninsula area by Germany, Japan, Korea, and the USA. Five oceanographic stations at 15 nautical mile intervals were selected north of Elephant Island along 55°W; water temperature, salinity, nutrients, phytoplankton, krill and other zooplankton, and acoustic backscatter were sampled by similar sampling protocols. The transect was surveyed six times during the austral summer, from early December 1994 to late February 1995. The major findings from this time-series were : 1) The north/south position of the oceanic frontal zone north of Elephant Island along 55°W varied by 15 nautical miles; the northeasterly current associated with this front, determined by geostrophy, varied in strength depending on position of the front; 2) Most chl-a was concentrated in the upper 50m above or near the pycnocline. Surface chl-a concentrations ranged from 0.5mg/m^3 to >3.5mg/m^3. Peak chl-a (3.62mg/m^3) was found in the surface water during 18 February 1995. 3) Krill spawning during the 1994/95 season was early, extensive and apparently successful compared to previous years; and 4) Taxa other than krill may have contributed substantially to the observed acoustic backscattering.