General Hydrography of the Beagle Channel, a Subantarctic Interoceanic Passage at the Southern Tip of South America

GIESECKE, RICARDO; MARTÍN, JACOBO; PIÑONES, ANDREA; HÖFER, JUAN; GARCÉS-VARGAS, JOSE; FLORES-MELO, XIMENA; ALARCÓN, EMILIO; DURRIEU DE MADRON, XAVIER; BOURRIN, FRANÇOIS; GONZÁLEZ, HUMBERTO E.

FRONTIERS IN MARINE SCIENCE

Frontiers Media SA

Año: 2021 vol. 8

2296-7745

The Beagle Channel (BC) is a long and narrow interoceanic passage (∼270 km long and 1–12 km wide) with west-east orientation and complex bathymetry connecting the Pacific and Atlantic oceans at latitude 55°S. This study is the first integrated assessment of the main oceanographic features of the BC, using recent oceanographic observations from cruises, moored instruments and historical observations. The waters transported into the BC are supplied mainly by the Cape Horn Current, which carries Subantarctic Water (SAAW) at depth (100 m below surface) along the Pacific Patagonian continental shelf break. SAAW enters the continental shelf via a submarine canyon at the western entrance of the BC. The SAAW is diluted by fresh, nutrient depleted (nitrate, phosphate and silicic acid) Estuarine Water (EW) from Cordillera Darwin Ice Field (CDIF) forming modified SAAW (mSAAW). Freshwater inputs from the CDIF generate a two-layer system with a sharp pycnocline which delimits the vertical distribution of phytoplankton fluorescence (PF). Two shallow sills (