Analysis of the hydrographic conditions and cyst beds in the San Jorge Gulf, Argentina, that favour dinoflagellate population development including toxigenic species and their toxins

BERND KROCK; C. MARCELA BOREL; FACUNDO BARRERA; URBAN TILLMANN; ELENA FABRO; GASTÓN O. ALMANDOZ; MARTHA FERRARIO; JOHN E. GARZÓN CARDONA; BORIS P. KOCH; CECILIA ALONSO; RUBÉN J. LARA

JOURNAL OF MARINE SYSTEMS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015

0924-7963

The overlay of cooler nutrient enriched Beagle-Magellan water with warmer nutrient depleted shelf water and a strong stratification of the water column in the San Jorge Gulf region, Argentina, coincided with relatively high dinoflagellate abundances in April 2012, up to 34,000 cells L-1. This dinoflagellate proliferation was dominated by Ceratium spp., but environmental conditions also favored to a lesser amount the occurrence of toxigenic dinoflagellates, such as Alexandrium tamarense and Protoceratium reticulatum, whose toxins were hardly detected in any other areas along the expedition transect of the R/V Puerto Deseado between 38 and 56 °S (Ushuaia-Mar del Plata) in March/April 2012. Generally vegetative cells of A. tamarense and P. reticulatum co-occurred with their respective phycotoxins in the water column and their cysts in the upper sediment layers. Two strains of A. tamarense were isolated from a bloom sample and morphologically characterized. Their PSP toxin profiles consisted of C1/2, gonyautoxins 1/4 and to a lesser amount of neosaxitoxin and confirmed earlier data from this region. The ratios between autotrophic picoplankton and heterotrophic bacteria were higher in shelf waters in the north than in Beagle-Magellan waters in the south of San Jorge Gulf.