Time filter

Source Type

Tacuarembó, Uruguay

Franco-Trecu V.,University of the Republic of Uruguay | Aurioles-Gamboa D.,National Polytechnic Institute of Mexico | Arim M.,University of the Republic of Uruguay | Arim M.,Centro Universitario Regional Este | And 2 more authors.
Journal of Mammalogy | Year: 2012

In Uruguay, the South American fur seal population (Arctocephalus australis) is increasing, whereas the South American sea lion (Otaria flavescens) population is declining. Previous research using fecal analysis suggested a high degree of trophic overlap between these species. In this study we used stable isotope analysis to assess whether trophic overlap occurs between female fur seals and sea lions during the breeding season. We measured 15N and 13C values in serum and skin from pups of both species (n 47) to reflect pre- and postpartum maternal feeding habits, respectively. Our results suggested a lack of trophic overlap between lactating females; both serum and skin samples from sea lion pups had significantly greater 13C and 15N values than samples from fur seal pups, suggesting that lactating sea lions forage near shore, whereas lactating fur seals forage offshore. The pre- to postpartum diet shift in fur seals would be mainly caused by a reduction in the diversity of the exploited trophic levels, whereas in sea lions the shift could be related to a decrease in the diversity of foraging areas used. The observed trophic segregation between these sympatric otariids is probably driven by their synchronous breeding and similar maternal strategies. © 2012 American Society of Mammalogists. Source

Schuerch M.,University of Cambridge | Scholten J.,University of Kiel | Carretero S.,National University of La Plata | Garcia-Rodriguez F.,Centro Universitario Regional Este | And 3 more authors.
Geomorphology | Year: 2016

The vertical growth of coastal wetlands is known to primarily be controlled by local tidal range and sediment availability as well as the occurrence of storm events. In estuaries, sediment availability additionally depends on riverine sediment input, the effect of which may be more pronounced in some parts of the estuary, thereby introducing a distinct spatial pattern that depends on the estuary's shape as well as the riverine sediment input and the hydro-meteorological regime. In the present study, we investigate how estuarine marshes along the whole Río de la Plata (RdlP) are affected by decadal and long-term variations in river discharge and storm activity. The El Niño Southern Oscillation (ENSO), in this context, appears to introduce a pronounced decadal variability on sediment loads brought into the RdlP. Based on 15 sediment cores, recovered along the RdlP and adjacent Atlantic coast, vertical marsh growth rates were studied using radionuclide dating (210Pb and 137Cs) and grain size distributions. By comparing these sedimentological records with historic river discharge and storm surge data, we spatially interpret the relative importance of temporal variations in river discharge and storm activity on estuarine marsh growth. By delivering the first estimates for vertical growth rates of the RdlP marshes, we conclude that with average vertical marsh growth rates between 0.4 and 2.6 cm year− 1, the RdlP marshes are highly resilient against drowning under present and future sea-level rise (SLR) conditions. Furthermore, our results confirm a large spatial variability of the drivers for vertical marsh growth; extreme storm surges appear to play a role in the development of the outer RdlP marshes whereas the temporal variations in river discharge seem to be hierarchically more important for the marshes in the inner estuary. © 2016 Elsevier B.V. Source

Bozzeda F.,University of Bologna | Zangrilli M.P.,University of Bologna | Defeo O.,UNDECIMAR | Defeo O.,Centro Universitario Regional Este
Estuarine, Coastal and Shelf Science | Year: 2016

A Fuzzy Naïve Bayes (FNB) classifier was developed to assess large-scale variations in abundance, species richness and diversity of the macrofauna inhabiting fifteen Uruguayan sandy beaches affected by the effects of beach morphodynamics and the estuarine gradient generated by Rio de la Plata. Information from six beaches was used to estimate FNB parameters, while abiotic data of the remaining nine beaches were used to forecast abundance, species richness and diversity. FNB simulations reproduced the general increasing trend of target variables from inner estuarine reflective beaches to marine dissipative ones. The FNB model also identified a threshold value of salinity range beyond which diversity markedly increased towards marine beaches. Salinity range is suggested as an ecological master factor governing distributional patterns in sandy beach macrofauna. However, the model: 1) underestimated abundance and species richness at the innermost estuarine beach, with the lowest salinity, and 2) overestimated species richness in marine beaches with a reflective morphodynamic state, which is strongly linked to low abundance, species richness and diversity. Therefore, future modeling efforts should be refined by giving a dissimilar weigh to the gradients defined by estuarine (estuarine beaches) and morphodynamic (marine beaches) variables, which could improve predictions of target variables. Our modeling approach could be applied to a wide spectrum of issues, ranging from basic ecology to social-ecological systems. This approach seems relevant, given the current challenge to develop predictive methodologies to assess the simultaneous and nonlinear effects of anthropogenic and natural impacts in coastal ecosystems. © 2016 Elsevier Ltd. Source

Celentano E.,UNDECIMAR | Defeo O.,UNDECIMAR | Defeo O.,Centro Universitario Regional Este
Marine Ecology Progress Series | Year: 2016

Climate change is expected to have considerable impacts on sandy beach ecosystems through the loss of intertidal area and changes in physical properties. These changes may affect demography and life history traits of macrofaunal species. We evaluated the role of climate in explaining variations in population traits of the mole crab Emerita brasiliensis over 20 yr on a sandy beach in Uruguay, based on a set of predictive hypotheses recently developed from studies of beach and climate-change ecology. Population abundance increased with sea surface temperature (SST), reproductive and recruitment periods were more extended, and recruitment was higher during warm years, when population structure showed a multi-modal structure. Decreasing asymptotic sizes and increasing growth rates were also observed concurrently with increasing SST. La Niña events, which in coastal Uruguayan waters are characterized by a higher influence of tropical oceanic waters (warm and salty), had marked positive impacts on abundance and individual growth. In a climate change scenario, an increasing frequency of extreme La Niña events is expected and therefore our results have strong implications. In a space-for-time substitution context, our long-term trends are reinforced by macroscale results that reported an increase in growth rates and in reproduction and recruitment periods, together with a decrease in female individual sizes, from temperate to tropical beaches of the Atlantic coast of South America. Spacefor-time substitution is highlighted as an alternative approach to analyze potential population changes resulting from climate change in these data-poor ecosystems. © 2016 Inter-Research. Source

Garcia-Alonso J.,Natural History Museum in London | Garcia-Alonso J.,Centro Universitario Regional Este | Rodriguez-Sanchez N.,Natural History Museum in London | Rodriguez-Sanchez N.,Liverpool John Moores University | And 8 more authors.
Science of the Total Environment | Year: 2014

Pollutants affecting species at the population level generate ecological instability in natural systems. The success of early life stages, such as those of aquatic invertebrates, is highly affected by adverse environmental conditions. Silver released into the environment from emerging nanotechnology represents such a threat. Sediments are sinks for numerous pollutants, which aggregate and/or associate with depositing suspended particles. Deposit feeder such as the annelid Platynereis dumerilii, which has a large associated literature on its development, is an excellent model organism for exposure studies in coastal environments. We exposed eggs, larvae, juveniles and adults of P. dumerilii to various concentrations of citrate (cit-Ag NPs) or humic acid (HA-Ag NPs) capped silver nanoparticles (Ag NPs) as well to dissolved Ag (added as AgNO3). We showed that mortality and abnormal development rate increased with younger life stages. While adults and juvenile were the most tolerant life stages, fertilized eggs were highly sensitive to AgNO3, cit-Ag NPs and HA-Ag NPs. Exposures to HA-Ag NPs triggered the highest cute toxicity responses in P. dumerilii and in most cases both Ag NPs were more toxic than AgNO3. Uptake rate of HA-Ag NPs in adult worms was also higher than from other Ag forms, consistent with toxicity to other life stages. The early stages of the life cycle of marine coastal organisms are more affected by Ag NPs than the juvenile or adult life stages, indicating that exposure experiments at the larval level contribute to realistic eco-toxicological studies in aquatic environments. © 2014 Elsevier B.V. Source

Discover hidden collaborations