Antarctic Sound Research Articles

Food and feeding ecology of postlarval and juvenile Pleuragramma antarcticum (Pisces; Notothenioidei) in the seasonal pack ice zone off the Antarctic peninsula

Stomach contents of 275 postlarval and 269 one year old juvenile Pleuragramma antarcticum caught in February 1982, March 1981 and November 1977 in the Bransfield Strait and adjacent waters were investigated. Juveniles in November 1977 fed mainly on calanoid copepods and Oithona spp. The principal food of postlarvae in February 1982 were Oncaea spp., eggs of calanoid copepods and tintinnids whereas the staple food of juveniles in February 1982 consisted of calanoid copepods of which copepodites of Calanus propinquus were most abundant. Eggs of Euphausia superba were frequently ingested by postlarvae and were the main component of the juvenile diet in the Antarctic Sound. Postlarvae in March 1981 preyed on Oncaea spp. and calanoid eggs. There was a shift from feeding on cyclopoid copepods by postlarvae to feeding on calanoids by juveniles. The food particle size increased as a function of fish length. Maximum prey size was controlled by mouth width up to at least 45 mm standard length. Prey selection was apparently food density dependent with an inverse relationship between food abundance and selective feeding. Density dependent size selection may have resulted in resource partitioning among postlarval and juvenile fishes in February. This specific feeding behaviour is likely to be an adaptation to the low zooplankton stocks of the high Antarctic shelf waters to minimize food competition among the youngest age classes. Predation on krill eggs indicated that the frequent association of one year old juvenile Pleuragramma antarcticum with the Antarctic krill is related to local spawning events.

Geology of the West End of Ymer Island, East Greenland

INTRODUCTION LOCATION The writers sailed as guests, in the summer of 1933, on the expedition led by John K. Howard, of Boston, to the fjord region of East Greenland. The expedition assembled at Isafjord, Iceland, on July 31, and sailed north in the Norkap II, a Norwegian sealer which had been outfitted for the voyage in Gloucester, Massachusetts. The geological work was carried on in the western part of Ymer Island, between 73° and 73°30′ north latitude. This island is separated from the mainland by Franz Josef Fjord, on the north and west, and by Antarctic Sound, on the south, each an important member in the fjord system of this part of the Greenland coast. STATEMENT OF THE PROBLEM The general problem involved a study of the structure and the stratigraphy of strata in the west end of Ymer Island. This problem became resolved into a number of specific studies, . . .

The Geological Work of the Cambridge Expedition to East Greenland in 1929

East Greenland, a country of high coastal mountains receding under the cap-ice and of great fjords bounded by towering cliffs, has, within the last decade, attracted once again the attention of investigators. After an unsuccessful attempt in 1923, Mr. J. M. Wordie succeeded in reaching land and exploring Gael Hamkes Bay and Franz Josef Fjord in the very favourable ice year of 1926 (Wordie, 1927). That same summer, Dr. Lauge Koch took a party to Scoresby Sound, and himself made a sledge-journey the next spring northwards to Germania Land, returning by way of the fjords (Koch, 1929). Since Dr. Koch wished to elucidate further the stratigraphy of the Palæozoic rocks in 1929, the third Cambridge Expedition of 1929 concentrated mainly upon a determination of certain tectonic problems in the pre-Old Red Sandstone rocks, and upon a journey inland from Kjerulf Fjord into unknown country (Wordie, 1930). Had time permitted, a party was to sledge from the head of Gael Hamkes Bay as far north as Queen Louise Land, in order to determine the relations existing there between the sedimentary and metamorphic outcrops; but owing to delay in the pack-ice, this plan had to be abandoned. The large fjords, Franz Josef Fjord and King Oscar Fjord, are connected through Antarctic Sound, and measure respectively about 110 miles and 45 miles in length. They have many branches, most of which traverse the rock-sequences across the dip, and afford cliff-sections of multicoloured bare rock, often attaining 6000 feet in height. The fjord-system is