[1] Sea-air differences of CO 2 partial pressures (DpCO 2 ) and surface chlorophyll a (chl-a) concentration have been determined during 22 cruises in various seasons for 2000-2006 over the Patagonia Sea and shelf break. From spring to autumn, the nearshore waters act as a source of atmospheric CO 2 , while the midshelf and slope are a CO 2 sink, leading to highly negative areal means of sea-air CO 2 flux and DpCO 2 . The DpCO 2 and CO 2 flux in spring reach values of À67 matm and À7 Â 10 À3 mol m À2 d À1 , respectively, and are close to equilibrium in winter. Sea-air DpCO 2 and chl-a over the shelf are negatively correlated, suggesting that photosynthesis is one of the main processes responsible for the large CO 2 sequestration. The annual areal mean DpCO 2 and sea-air CO 2 flux are À31 matm and À3.7 Â 10 À3 mol m À2 d À1 , respectively, indicating that the Patagonia Sea is one of the strongest CO 2 sinks per unit area in the World Ocean.

Luz Clara, M.; Simionato, C.G.; D'Onofrio, E., and Moreira, D., 0000. Future sea level rise and changes on tides in the Patagonian Continental Shelf. Journal of Coastal Research, 00(0), 000-000. Coconut Creek (Florida), ISSN 0749-0208.We investigate the effect of the future sea level rise (SLR) on the propagation of tides in the Patagonian Shelf by means of numerical simulations. Using a barotropic implementation of the Model for Applications at Regional Scales (MARS), we obtain solutions for scenarios which represent the present condition and potential future SLRs of 1, 2, and 10 m. The effect of flooding of low-lying areas is studied, and its influence on the propagation of tides in the region is discussed. Due to the coastal morphological features and the sense of tidal wave propagation in the Southern Hemisphere, inundation does not significantly modify the solution in the Patagonian Shelf; nevertheless, results are substantially changed in the much lower Northern Argentinean Shelf, north of 408 S, where dissipation is increased. The amplitude of M 2 responds to SLR in a spatially nonuniform manner. The response is nonlinear, particularly in regions close to the amphidromic points. Tidal dissipation by bottom friction increases consistently by 16% for the more extreme scenario with a generalized increment of tidal amplitudes, and therefore currents, over the Patagonian Shelf. Changes in the extension and position of tidal fronts are also explored. The results suggest that changes will be significant, with a reduction of the mixed areas in Cabo Blanco and San Sebastián and an increment of them in the vicinity of Península Valdés. Physical mechanisms that explain the observed modifications in the tidal regime are the changes with SLR of the speed of the tidal wave, the Rossby radius of deformation, the energy dissipation by bottom friction, and the resonant properties of the basin. Similarly to numerical studies performed for other coastal areas of the world, results indicate that important changes in the characteristics of tides can occur if SLR is large.

The fish diversity and the main environmental factors affecting the spatial distribution of species, life history stages and community structure in the Río de la Plata (RdP) and adjacent waters are reviewed and analysed, with emphasis on the functional guild classification. The functional guild classification indicated that most species in the RdP were marine stragglers, zoobenthivores and oviparous species, although the biomass was dominated by estuarine species. Salinity had a stronger influence than temperature on the spatial pattern for all life stages, shallower and fresher waters are the preferred habitats of neonates and juveniles. During the breeding season (spring-summer), adults showed an intrusion into the inner part of RdP or to its adjacent nearshore waters from the offshore waters for spawning or mating, respectively. Variations in river discharge and wind patterns greatly affected the spatial extent of estuarine water, which ultimately influenced the domain of the main life-history stages (juveniles or adults) for both marine and estuarine fishes, as well as species and fish assemblage composition. The strong environmental gradient restricts some species and life-history stages to a particular section and defines three main fish assemblage areas. The composition of the fish assemblage is indicative of the recruitment of freshwater and marine species to the estuary in opposite ways, determined by the vertical stratification. Seasonal changes in the species composition were related to migration as a result of salinity and temperature variations and reproductive migrations to spawning and mating areas. This overview reveals that the RdP is under environmental variations that are likely to produce modifications to fish distribution and abundance that affect its fisheries. This context plus fish stock declines and changes in exploitation patterns could amplify the magnitude of the variations in the fisheries resources availability and affect the sustainability of fishing communities.