Polish Polar Research

The paper presents the trends of air temperature of the Antarctic. In its elaboration 21 stations were taken into consideration carrying out temperature measurements in the years 1958–2000, and 34 stations in the years 1981–2000. After checking the homogeneity of the series by the Alexandersson’s (1986) test we found that at 16 stations the homogeneity has been broken. On the basis of the corrected measurement series we have determined the trends in air temperature. In the period 1958–2000 statistically significant (on 0.95 significance level) temperature increases occurred on the western coast of the Antarctic Peninsula (for example Faraday 0.67°C/10 years) and at the Belgrano and McMurdo stations. The greatest temperature rise was noted on the Antarctic Peninsula during the autumn-winter period. On the South Pole a negative trend in air temperature (–0.21°C) occurred, especially in the summer season. During recent years (1981-2000) significant changes took place in the air temperature tendencies in the Antarctic. In many regions of the Antarctic cooling began and on the cost of East Antarctica the temperature decreased by –0.82°C/10 years (Casey). In the interior of the continent also lower and lower temperatures occurred (Amundsen-Scott –0.42°C/10 years, Dome C –0.71°C/10 years). The coast of the Weddell Sea is getting colder (Halley –1.13°C/10 years, Larsen Ice –0.89°C/10 years). An increase in temperature was observed in the interior of West Antarctica (Byrd 0.37°C/10 years). The warming rate of the climate became weaker on the Antarctic Peninsula (Faraday 0.56°C/10 years). The largest temperature changes occurred in the autumn-winter season when in the Antarctic Peninsula region the temperature increased, while in the interior and at the coast of East Antarctica temperatures fell considerably.

Energy delivered to the nests of Wilson's storm petrel, Oceanites oceanicus (Kuhl, 1820), was evaluated by measurement of the oxygen consumption of brooding adult birds and nestlings of different ages. During the brooding period adult birds have to deliver more than 180 kJ per visit to the nest vs. less than 170 kJ during the rest of the nesting period. It seems likely that the parental ability to deliver large quantities of food per visit affects the duration of the brooding period and therefore also affects growth rates of Wilson's storm petrel chicks and the duration of their nesting period.

The diet of the unsexed breeding Adélie penguin (Pygoscelis adeliae Hombron et Jacquinot, 1841) was investigated during three consecutive chick rearing periods, from 1996–97 to 1998–99, on Laurie Island, South Orkney Islands (60°46’S, 44°42’W), Antarctica. This analysis showed that during the whole sampling period, Antarctic krill (Euphausia superba Dana, 1852) represented the predominant prey in terms of frequency of occurrence, mass, and number. The hyperiid amphipod Themisto gaudichaudii (Guerin-Méneville, 1825) was present in small amounts. Electrona antarctica (Gunter, 1878), Trematomus newnesi (Boulenger, 1902) and larval stages of Nototheniidae constituted the bulk of the fish portion, particularly during the 1997/98 and 1998/99 breeding periods. This study is the first examination of the Adélie penguin diet at Laurie Island. It is important to recognize, however, the importance of knowing the sex of the penguins being sampled and that prey composition may vary during the breeding season and from one year to the next.

A population survey of southern elephant seals (Mirounga leonina Linnaeus, 1758) was conducted at Nelson Island, South Shetland Islands, Antarctica, during the 2001 breeding season. Two breeding sites were identified, one of which had not been previously reported. The largest breeding site was located at Duthoit Point, with a total of 128 females, 111 pups and 7 weanlings distributed in 6 harems along 3 km of coast. The new breeding group was observed at Harmony Point, where 3 females with their pups were found. This is the first report on southern elephant seal numbers during the breeding period for the Nelson Island coast.

The zooplankton community structure was studied in the Svalbard area at three shelf stations: Billefjorden, Kongsfjorden and Hinlopen (Spitsbergen shelf area), and at two open water stations: Ice West and Ice East (north of Spitsbergen, in the Arctic Ocean). Two different plankton nets – WP-2 and WP-3 – were used to collect a size range of zooplankton. The Bray-Curtis similarity analysis showed differences between sampling stations based on total zooplankton abundance, species composition, and comparison of Calanus spp. development. Total abundance was the highest in Kongsfjorden and Hinlopen. The small omnivorous copepod Oithona similis Claus, 1863 was the dominating species at all localities and the Atlantic copepod Calanus finmarchicus (Gunnerus, 1765) was found at all stations. Calanus spp. development was delayed at the ice stations when compared to the shelf stations. Results are discussed in relation to differences in environmental factors among stations.

Mud samples from two lakes in West Greenland were kept frozen at –18°C for 18 years. When they were thawed, 4 Cladocera species hatched from diapausing eggs: Daphnia pulex (De Geer, 1778), Macrothrix hirsuticornis (Norman et Brady, 1867) and Chydorus arcticus (Rřen, 1987), which are by far the most abundant Cladocera species in the high Arctic north of 74°N. Another species was Alona quadrangularis (O. F. Müller, 1785), which occurs up to 72°N. All these species gave rise to parthenogenetic offspring and produced ephippia within a time frame comparable to an Arctic summer season. Up to 9 other Cladocera species were likely to be present in the original populations, but did not hatch anymore after 12 years.