Seabird abundance, biomass and prey consumption within Prydz Bay, Antarctica, 1980/1981-1992/1993

Annual observations of seabirds within Prydz Bay, East Antarctica, between the 1980/1981 and 1992/1993 seasons revealed significant changes in abundance of the 9 resident and 15 non-resident species. An estimated 4.85 million individual residents and 2.35 million individual non-residents were present each season. For resident and non-resident species, mean abundance was 3.75 and 1.81 birds/km(2), and mean biomass was 6.67 and 1.70 kg/km(2), respectively. Based on estimated abundances, the total consumption of marine resources by the seabird community within Prydz Bay ranged from 471,000 to 1.1 million tonnes (mean 752,000 +/- 176,000 tonnes) per 6-month summer, or between 2.02 and 4.53 kg/km(2) per day (mean 3.23 +/- 0.76 kg/km(2) per day). The mean energy flux to the seabird community within Prydz Bay each summer was 3.13 * 10(12) kJ, (range: 2.0 * 10(12) kJ-4.4 * 10(12) kJ), of which 66% went to the resident species. Regional abundance and biomass estimates for resident and nonresident species were both negatively correlated; when the estimated abundance and biomass of resident species were high, those of non-resident species were low.