Euphausiids in the Coral and Tasman Seas during May 1972. II. Horizontal Distribution in relation to Circulation Patterns

Abstract

An examination of the euphausiid species collected at two stations, 20º S.,153º E. and 33º 40'S.,153º E., during May 1972 showed that 21 of the 33 epipelagic and mesopelagic species were common to both stations. This suggests a high degree of water mass continuity between these two stations. This paper discusses the horizontal distribution of 10 species, divided into four groups, who show range extensions that are related to circulation patterns in the Coral and Tasman Seas. The presence of group A animals (Thysanopoda tricuspidata, Euphausia diomedeae, E. pseudogibba, and Nematoscelis gracilis) at the southern station supports the theory that there is a southward movement of South Equatorial water from between the Solomon Islands and New Caledonia to at least 33º 44'S. This water must have passed over, or close to the continental shelf, probably as part of the East Australian Current in order for the neritic Pseudeuphausia latrifrons (group B) to be caught at the southern station. The species present in group C (Euphausia similis and Thysanoessa gregaria) indicate there had been northern transport of central Tasman water to at least 20º S., possibly along 160º E. or further east. Finally, the group D species (Euphausia brevis, Nematoscelis atlantica and N. tenella) suggest there may have been some westwards flow from the west central Pacific region, possibly during the previous June-December period.