Two records of subtropical grenadiers in the cold temperate Southwest Atlantic

Abstract

The Southwest Atlantic is a dynamic region that includes the Patagonian Shelf Large Marine Ecosystem (PLME) extending from Uruguay to the Strait of Magellan. It is one of the most productive and complex marine ecosystems in the world (Bakun, 1993). Oceanographic features of the PLME are governed by the transport of sub-Antarctic cold waters along the slope to temperate latitudes by the Falkland Current. This current flows northward to ∼38° S where it collides with the southward-flowing Brazil Current (Fig. 1). Both streams then veer offshore and form an intensive thermohaline front. The Falkland Current provides the PLME with a distinctive regional surface and subsurface boundary to the east (Bakun, 1993). The deep sea circulation (below ∼500 m) in the PLME is characterised by the presence of the North Atlantic Deep Water (NADW). This water represents a warm, highly saline, oxygen rich and nutrient poor layer extending from the North Atlantic southward across the equator. North of 55° S the NADW joins the Upper Circumpolar Deep Water (UCDW) and its derivative—the Antarctic Intermediate Water—and turns eastward with the Circumpolar Current (Gordon, 1986; Reid, 1989).