Biomass, production and microhabitat characteristics near the freeboard of ice floes in the Ross Sea, Antartica, during the austral summer

Abstract

The physical, chemical and biological characteristics of surface and free-board habitats in the summer pack ice in the eastern Ross Sea, Antarctica, were documented in a continuing effort to determine the factors controlling the distribution, production and succession of sea-ice biota. Three longitudinal transects from approximately 65° to 74° S in the western Ross Sea along 135°, 150° and 165° W were visited where samples of slush and slush interstitial water from surface and freeboard habitats as well as sea water were collected at every degree of latitude. Freeboard and surface habitats, found at all stations in the pack ice, contained a large range (five orders of magnitude) of micro-algal biomass (measured as chlorophyll a concentrations) and nutrients ranging from below levels of detection to those of the surrounding sea water. The geophysical attributes of the freeboard habitat (i.e. a layer of semi-consolidated ice overlying a layer containing unconsolidated ice crystals and sea water) are consistent with previous descriptions of this environment. However, additional information is presented on the range of biomass concentrations as well as the small-scale distributions of the habitat and biota.