Icy cores obtained during Octobe--November 1981 from Weddell Sea pack ice were analyzed for physical, chemical, and biological parameters. Frazil ice, which is associated with dynamic, turbulent conditions in the water column, predominated (70%). Both floe thickness and salinity indicate ice which is less than 1 year old. Chemical analyses, particularly with regard to the nutrients, revealed a compklex picture. Phosphate values are scattered relative to the dilution curve. Nitrate and silicate values are lower than expected from simple scaling with salinity and suggest diatom growth within the ice. Nitride values are higher in the ice than in adjacent waters. Frazil ice formation which probably concentrates algal cells from the water column into ice floes results in high initial chlorophyll a concentrations in the ice than in adjacent waters. This mechanical concentration is further enhanced by subsequent reproduction within the ice. Ice core chlorophyll ranged from 0.09 to 3.8 mg/m3, comparable to values previously reported for this area but significantly lower than values for Antarctic coastal fast ice. The dominance of frazil ice in the Weddell is one of the major differences between this area and others. Consequently, we believe that ice structural conditions, significantly influence the biological communities in the ice.