The phytoplankton of the Patagonian Shelf-Break Front

Abstract

Intense phytoplankton blooms in the Patagonian Shelf-Break Front (PSBF) in the southwest Atlantic Ocean (˜35°S-55°S) are responsible for making this large marine ecosystem one of the most productive and rich in resources and biodiversity of the Global Seas. This systematic review presents an up-to-date knowledge of the phytoplankton community composition, biomass and primary productivity along the permanent PSBF from temperate to subpolar latitudes. The interaction between wind stress, shelf waters, the steep slope and western energetic edge currents (i.e. Malvinas and Brazil Currents) originates upwelling areas and phytoplankton outbreaks, with maxima in spring and summer. In a sub-regional scale, the structure of the phytoplankton community is driven by the interplay between the complex geomorphological and hydrographical characteristics across the shelf-to-open ocean transition, also modulated by seasonal changes in light, nutrients and grazing pressure. Hence, different assemblages of phytoplankton functional groups and size-classes are observed along contrasting areas of the PSBF. Phytoplankton blooms have been studied from field observations in oceanographic cruises, satellite imagery and modelling. As a general outcome, blooms of micro-phytoplankton, e.g. large diatoms and dinoflagellates, are responsible for the high chlorophyll levels in austral spring, while blooms of pico-and nanophytoplankton occur in summer, e.g. blooms of calcified and non-calcified haptophytes such as the coccolithophore Emiliania huxleyi and Phaeocystis antarctica.

Wind‐driven currents and water masses shape spring phytoplankton distribution and composition in hydrologically complex, productive shelf waters

“…There are scarce data on the nutrient conditions of the Patagonian shelf, mostly focused on the PSBF (Supporting information Table S2; Guinder et al 2023). Nutrients measured in this study (Supporting Information Table S2) are in agreement with the ranges reported in the literature, and show that in general dissolved inorganic nutrients increase from the shelf to the shelf‐break.…”

“…The spatial heterogeneity of surface phytoplankton blooms and their governing factors in the Patagonian shelf have been studied mostly from satellite chlorophyll a (Chl a ) estimations and in a lesser extent from in situ measurements, as revised in Guinder et al (2023). Even less studied are the phytoplankton blooms in the transition across the 40°S parallel, a portion of the shelf which embraces the shallow area of El Rincón and the mid‐shelf and shelf‐break fronts, with a particularly complex hydrography (Guinder et al 2018; Ferronato et al 2021).…”