Physico-chemical characterization of the benthic environment of the Golfo San Jorge, Argentina

Abstract

The benthic system of the Golfo San Jorge was characterized from physico-chemical parameters based on samplings obtained during seasonal research cruises carried out on board the INIDEP vessels from springtime 1999 through wintertime 2000. Spatial and seasonal variations of temperature, salinity, density, oxygen content and chlorophyll-a in bottom water and concentration of total organic matter, total organic carbon, total nitrogen, chlorophyll-a and phaeopigments in sediments were analysed. The origin and nutritional value of the deposited organic matter were also assessed. The behaviour of the physico-chemical characteristics of the benthic habitat, studied applying statistical techniques, de¢ned three sectors with particular characteristics and minimum seasonal variations: sector 1, the largest and deepest one, comprises the central area of the gulf and corresponds to a depositional environment; sector 2 comprises the areas next to the extremes of the gulf and corresponds to a £ow or erosive environment; sector 3 includes the coastal area and south-east part of the gulf and belongs to a transitional environment.

Synoptic oceanography of San Jorge Gulf (Argentina): A template for Patagonian red shrimp (Pleoticus muelleri) spatial dynamics

“…There are no rivers flowing into the gulf; precipitations are scarce (average: 233 mm yr −1 in Comodoro Rivadavia). Sediments from the central basin of the gulf, a depositional environment, are dominated by fine silt and rich in organic carbon derived from seasonally high phytoplanktonic primary production in the upper layer of the water column (Fernández et al, 2003(Fernández et al, , 2005(Fernández et al, , 2008; continental input is negligible. Consistently, oxygen concentration in near-bottom water is lowest in the central basin (Fernández et al, 2005).…”

“…1a). The latter, formed by the discharge from the Magellan Strait, extends along inner shelf of southern Patagonia (Palma and Matano, 2012), entering the southeast sector of SJG around Cape Tres Puntas (Cucchi Colleoni and Carreto, 2001;Fernández et al, 2005); in the adjacent shelf, the axis of the plume matches the 100 m isobath, which shifts offshore at the latitude of SJG.…”

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

“…The SJG water mainly originates from SW modified by the contributions of coastal waters, whose salinity spatially and temporally varies between 33.0 and 33.6 (Fernández et al, 2007). Coastal waters flow northward from the Strait of Magellan along the coast (Fig.…”

Succession in subtidal macrofouling assemblages of a Patagonian harbour (Argentina, SW Atlantic)

“…Since diVerences between upward-oriented assemblages that started in diVerent seasons were mainly due to ephemeral algae, the observed eVect seems more inXuenced by the species that happened to be abundant during the last months before panel collection rather than to the early successional events that occurred just after the panels were deployed. San Jorge Gulf is characterised by a typical temperate seasonal cycle and signiWcant temporal variation of the nutrient concentration in sediments (Fernández et al 2005(Fernández et al , 2008. Thus, seasonality in algal growth is most likely related to seasonal variability of environmental conditions.…”

“…Salinity shows minor variations around 33.4-33.7 psu, due to the absence of freshwater courses and the scarcity of precipitation in the area (Paruelo et al 1998;Bertness et al 2006). Oceanographic surveys of San Jorge Gulf conWrm this pattern for the coastal zone, where the extreme values recorded for 1999 and 2000 ranged between 33.1 and 33.8 psu (Fernández et al 2005).…”