Green krill, the indicator of micro- and nano-size phytoplankton availability to krill

Size fractionated chlorophyll-a concentrations of surface seawater was measured (pico-, nano-, and micro-size fractions) during commercial krill operations in the waters north of the South Shetland Islands from late December, 1991 to mid-February, 1992. The proportion of green krill had significant regressions with chlorophyll-a concentrations in micro and nano- size fraction. This result shows the importance of micro- and nano-size phytoplanktons in terms of food source for the Antarctic krill in the natural environment.