Reconnaissance of the Balleny Islands

A reconnaissance expedition took place around the Balleny Islands in the 1963-1964 field season with the objective to examine the four beaches where landings had previously been made and to search for other likely landing places. All of the four previous landing places were examined by helicopter and on two of them landings were made (Borredaile and Sabrina Islands). Gravity and magnetic measurements were obtained on Sabrina and Borradaile Islands at approximately mean sea level. Magnetic measurements were taken in approximately the same position as the gravity measurements. Mammal and bird observations were conducted throughout the entire reconnaissance. Oceanography and marine biology was carried out and was divided into three parts. Firstly, the depths and nature of the sea floor in the vicinity of the islands were determined by continuous echo-soundings. About 300 miles of soundings close inshore provide the basis for the first detailed bathymetry of the islands. Secondly, a number of benthic stations were made on an arbitrarily planned grid. Dredging and trawling was conducted at most stations to determine whether the bottom fauna was entirely Antarctic in composition or whether due to the presence of the Balleny Macquaries ridge, elements of a subantarctic Macquarie or New Zealand fauna were represented in the Balleny Islands benthos. The bottom sediment was described. The principal group of animals collected at these benthic stations were the Echinodermata including Asteroidea (starfish), Ophiuroidea (brittle stars), Echinoidea (sea urchins), Crinoidea (sea lillies) and Holothuroidea (sea cucumbers). Other animals collected were Porifera, Polychaeta, Pycnogonida, Actinaria, Bryozoa and Scleractinia. The third aspect of the oceanographic work was the collection of water samples at two stations to the north and south of the Balleny Islands as part of a survey of patterns of distribution of marine bacteria in the Southern Ocean. A number of heterotrophic marine bacteria were later successfully isolated in the laboratory from these samples.