Is Gelatinous Zooplankon related to oceanographic characteristics in San Matías Gulf (Patagonia, Argentina)? A preliminary approach using satellite images.

GUERRERO, ELENA; WILLIAMS, GABRIELA NOEMÍ; GONZÁLEZ, RAÚL; GAGLIARDINI, DOMINGO ANTONIO

Puerto Madryn

Workshop; SAC-D/Aquarius Workshop; 2008

CONAE

San Matías Gulf (SMG) is located on the South Western Atlantic coast, between 40º 50’ and 42º 15’S. This semi-closed ecosystem of 17900 Km2 has very singular hydrographical characteristics changing along the annual cycle. During autumn and winter, surface sea temperature (SST) is homogenous in the whole gulf, in contrast to spring and summer when a thermal front appears. This frontal system divides warmer and salty water on the northern part from colder and less salty water on the southern part of the SMG. It is known that thermal fronts generate a biological barrier due to different densities of water masses confronted. Consequently, small plankton organisms can not pass through it, causing accumulation of primary and secondary production. Studies performed during the last five years, demonstrated that highest hake Merluccius hubbsi catch rates have occurred on the front area during summer months. Gelatinous zooplankton has an important role in the ecosystems since they are carnivore predators, competing with fish for the same resources and also preying on fish eggs and larvae. In this study we analysed presence and abundance of gelatinous zooplankton (hydromedusae and siphonophora) from four research cruises (Series NORPAT 2007/2008) that were carried out in the SMG along an annual cycle, and their potential relationship with SST data, obtained from NOAA/AVHRR satellite images. We discuss the usefulness of remote sensing data to link gelatinous zooplankton distribution and abundance to environmental features in this study area.