Light absorption by phytoplankton, non-algal particles and dissolved organic matter in the San Jorge gulf in summer.

WILLIAMS, GABRIELA NOEMÍ; LAROUCHE, PIERRE; DOGLIOTTI, ANA INÉS; LATORRE, MAITÉ P.

OCEANOGRAPHY

OCEANOGRAPHY SOC

Lugar: Rockville; Año: 2018

1042-8275

The San Jorge Gulf is a region of high ecological importance where several industrial fisheries exploit species like hake, the Argentine red shrimp and the Patagonian scallop. In this region, phytoplankton distribution is often related to bathymetric or oceanographic features such as capes, upwelling, and frontal areas that drive the renewal of nutrients in the surface layer. Remote sensing is a key tool to monitor such a large ecosystem. Knowledge of the optical properties in this area is however necessary to assess the quality of operational ocean color products. Absorption by phytoplankton (aphy), non-algal particles (aNAP), colored dissolved organic matter (aCDOM) and chlorophyll-a concentration was measured in February 2014 in the surface layer of the San Jorge Gulf. There was a strong spatial variability of all parameters within the gulf resulting from the large-scale circulation and bathymetric features. Even though CDOM dominated the absorption budget, there was a good correlation between aCDOM and aphy leading to the characterization of the San Jorge Gulf as ?Case-1? waters where remote sensing algorithms should perform well. Results showed that the phytoplankton composition was mainly dominated by small size cells (0.2-2 µm, i.e. pico-phytoplankton). The aphy*(440) measured at the end of summer in the SJG (0.01-0.08 m2 mg-1) are in a similar range to those observed elsewhere. The particulate absorption was dominated by phytoplankton (66%).