Dynamical connections between large marine ecosystems of austral South America based on numerical simulations

PIOLA, ALBERTO R.; GUIHOU, KAREN; CHIDICHIMO, MARIA PAZ; PALMA, ELBIO D.

OCEAN SCIENCE (OS)

COPERNICUS PUBLICATIONS

Lugar: Gottingen; Año: 2020 vol. 16 p. 271 - 290

1812-0784

The Humboldt Large Marine Ecosystem (HLME)and Patagonian Large Marine Ecosystem (PLME) are thetwo largest marine ecosystems in the Southern Hemisphereand are respectively located along the Pacific and Atlanticcoasts of southern South America. This work investigates theexchange between these two LMEs and its seasonal and interannualvariability by employing numerical model resultsand offline particle-tracking algorithms. Our analysis suggestsa general poleward transport on the southern region ofthe HLME, a well-defined flux from the Pacific to the Atlantic,and equatorward transport on the PLME. Lagrangian simulations show that the majority of thesouthern PS waters originate from the upper layer in thesoutheast South Pacific ( < 200 m), mainly from the southernChile and Cape Horn shelves. The exchange takes placethrough the Le Maire Strait, Magellan Strait, and the shelfbreak. These inflows amount to a net northeastward transportof 0.88 Sv at 51 S in the southern PLME. The transportacross the Magellan Strait is small (0.1 Sv), but due to its relativelylow salinity it greatly impacts the density and surfacecirculation of the coastal waters of the southern PLME. Thewater masses flowing into the Malvinas Embayment eventuallyreach the PLME through the Malvinas Shelf and occupythe outer part of the shelf. The seasonal and interannual variabilityof the transport are also addressed. On the southernPLME, the interannual variability of the shelf exchange ispartly explained by the large-scale wind variability, whichin turn is partly associated with the Southern Annular Mode(SAM) index (r =0.52).