ABSTRACT: Sea ice communities were sampled across the Ross Sea in the austral autumn. The biota in first-year pack ice was assessed by measuring chlorophyll a (chl a), phaeopigments, total particulate carbon and nitrogen (POC and PON,respectively) and collecting samples for identification by microscopy. Physical and chemical parameters were also measured to characterize the environment. Chl a concentrations in ice ranged from 0 to 96.9 µg l^-1 in discrete samples andfrom 0.02 to 20.9 mg m^-2 for values integrated throughout floes. Maximum values were similar to those observed in first-year pack ice at other Antarctic locations. Chl a concentrations varied with ice structure and with latitude. POC:chla and C:N ratios (molar) were high, possibly indicating detritus accumulations. The higher chl a levels north of approximately 72°S were apparently a result of ice forming in the south early in the season with subsequent advection to thenorth. These dynamics would result in older ice in the mid- or northern pack ice zone that was maintained in a favorable light and temperature regime during the seasonal progression of formation and drift. Chlorophyll levels were low in surface-layercommunities. High chlorophyll concentrations were associated with internal communities. Bottom-layer algal populations, while present, did not reach the levels of high biomass reported for autumn blooms in some land-fast ice regions. Apparent nutrient andCO₂ depletion were correlated with biomass parameters but accounted qualitatively for only a fraction of the biomass accumulation measured. Overall, autumn ice-associated production in the Ross Sea may be lower than expected because of the icedrift dynamics, apparently low production in the near-surface layers of first year ice flows, and the absence of rich bottom-layer assemblages.