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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.


Perez L.,University of the Republic of Uruguay | Perez L.,Centro Universitario Regional Este | Garcia-Rodriguez F.,University of the Republic of Uruguay | Garcia-Rodriguez F.,Centro Universitario Regional Este | And 2 more authors.
Climate of the Past | Year: 2016

The continental shelf adjacent to the Río de la Plata (RdlP) exhibits extremely complex hydrographic and ecological characteristics which are of great socioeconomic importance. Since the long-term environmental variations related to the atmospheric (wind fields), hydrologic (freshwater plume), and oceanographic (currents and fronts) regimes are little known, the aim of this study is to reconstruct the changes in the terrigenous input into the inner continental shelf during the late Holocene period (associated with the RdlP sediment discharge) and to unravel the climatic forcing mechanisms behind them. To achieve this, we retrieved a 10 m long sediment core from the RdlP mud depocenter at 57 m water depth (GeoB 13813-4). The radiocarbon age control indicated an extremely high sedimentation rate of 0.8 cm per year, encompassing the past 1200 years (AD 750-2000). We used element ratios (Ti/Ca, Fe/Ca, Ti/Al, Fe/K) as regional proxies for the fluvial input signal and the variations in relative abundance of salinity-indicative diatom groups (freshwater versus marine-brackish) to assess the variability in terrigenous freshwater and sediment discharges. Ti/Ca, Fe/Ca, Ti/Al, Fe/K and the freshwater diatom group showed the lowest values between AD 850 and 1300, while the highest values occurred between AD 1300 and 1850. The variations in the sedimentary record can be attributed to the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA), both of which had a significant impact on rainfall and wind patterns over the region. During the MCA, a weakening of the South American summer monsoon system (SAMS) and the South Atlantic Convergence Zone (SACZ), could explain the lowest element ratios (indicative of a lower terrigenous input) and a marine-dominated diatom record, both indicative of a reduced RdlP freshwater plume. In contrast, during the LIA, a strengthening of SAMS and SACZ may have led to an expansion of the RdlP river plume to the far north, as indicated by higher element ratios and a marked freshwater diatom signal. Furthermore, a possible multidecadal oscillation probably associated with Atlantic Multidecadal Oscillation (AMO) since AD 1300 reflects the variability in both the SAMS and SACZ systems. © 2016 Author(s).


Mourelle D.,CONICET | Prieto A.R.,CONICET | Perez L.,University of the Republic of Uruguay | Perez L.,Centro Universitario Regional Este | And 3 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

In the present study, we carried out pollen, diatom and other palynomorph analyses from a sedimentary sequence from the marshes of Arroyo Solís Grande, in the Río de la Plata northeastern coast (Uruguay), and compared the results with a regional model of surface pollen-vegetation relationship from the Atlantic coastal salt marshes (30°-37° S). Results indicated that salt marsh vegetation developed around the estuary between 8000 and 5100. cal. yr BP, as the sea level rose and reached the Holocene sea-level highstand. Brackish marshes around the estuary between 5100 and 2900. cal. yr BP reflect the late Holocene sea-level fall and associated increased input of freshwater. Brackish marshes and shallow salt pond environments between 2900 and 1000. cal. yr BP are most probably linked to the Paraná delta formation and a further sea-level fall. Present-day marshes behind the sand bar characterize the last 1000. cal. yr BP. The integration of our results with multiproxy records from the Río de la Plata southern coast (Argentina) and from the coastal plain of the southern Atlantic margin of South America (30°-37° S) revealed that marine influence during the maximum sea-level highstand resulted in the development of vegetation similar to that of the geographical region. However, after ca. 3000. cal. yr BP, local differentiation related to different climate and geomorphology occurred at each area, thus resulting in the establishment of different modern plant communities at different times during the late Holocene. © 2015 Elsevier B.V.


Mourelle D.,Centro Universitario Regional Este | Prieto A.R.,CONICET | Garcia-Rodriguez F.,Centro Universitario Regional Este
Revista Brasileira de Paleontologia | Year: 2015

The palynological analysis from a sedimentary sequence from the wetland Paso Barranca-India Muerta at Laguna Merín Basin (RB1 core, 33°40’36”S-53°49’15”W) of southeastern Uruguay, allowed to reconstruct the vegetation history during the last ca. 2000 cal. yr BP. The modern pollen-vegetation relationship from Laguna Merín Basin at regional scale was used for the interpretation of RB1 fossil record. Results revealed that during the late Holocene grassland vegetation dominated at Paso Barranca-India Muerta, together with the development of riparian forests, palm grooves and freshwater marshes. This suggests a diverse vegetation on the area under either humid climatic conditions or a positive water balance. However, the freshwater marsh showed fluctuations in depth and extent, probably as a response to local soil water content changes. Since ca. 2000 cal. yr BP the marsh water level changes displayed variability, with increased levels at ca. 700 cal. yr BP. Thereafter, conditions remained relatively steady until ca. 300 cal. yr BP, when the marsh water level progressively increased until reaching the current conditions. The local soil water content changes would have responded to the late Holocene climate variability suggested for southeastern Uruguay, even under humid conditions proposed for the campos region of the Río de la Plata grasslands. The vegetation changes inferred from the palynological analysis could not be related to the anthropogenic changes introduced by the prehispanic populations in the region. This work substantially improves our knowledge of the late Holocene vegetation and climate conditions in the Laguna Merín Basin. © 2015 by the Sociedade Brasileira de Paleontologia.


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.


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.


Mourelle D.,Centro Universitario Regional Este | Prieto A.R.,National University of San Juan
Acta Botanica Brasilica | Year: 2016

In this study we describe and illustrate pollen and spores that have been identified as significant in modern and fossil samples from the campos region of Uruguay. We provide new information about modern pollen assemblages and their relationship to the vegetation types of this region. We discuss the taxonomic limitations of pollen and spores and their representation in both modern and fossil samples. We highlight the importance of identifying both silent and key indicator taxa for making accurate paleoecological interpretations. We also emphasize the importance of knowing the pollination strategies of parental plants because many of them are zoophilous, and so small changes in the proportions of their pollen grains in fossil assemblages could reflect important changes in vegetation. This study presents a practical approach to paleoecological research, which not only produces robust results in studies of the campos region, but can be applied to other grassland ecosystems, including those in temperate regions. © 2016, Sociedade Botanica do Brasil. All rights reserved.


Gianelli I.,UNDECIMAR | Gianelli I.,Centro Universitario Regional Este | Martinez G.,Centro Universitario Regional Este | Defeo O.,UNDECIMAR | Defeo O.,Centro Universitario Regional Este
Marine Policy | Year: 2015

The Ecosystem Approach to Fisheries (EAF) has been proposed as a holistic approach for managing fisheries. Although EAF is a widely accepted concept, many challenges remain in its practical implementation, particularly in small-scale fisheries (SSFs) in developing countries. Long-term evaluations of EAF performance in SSFs are scarce and even fewer when considering co-management (Co-M) as the institutionalized governance mode implemented under an EAF scheme (EAF/Co-M). This paper addresses the implementation, development process and performance of an EAF/Co-M in the yellow clam SSF of Uruguay through multiple fishery indicators for the period 2007-2015. EAF/Co-M showed a highly positive response in abundance and biomass of the harvestable stock through time, stabilization in individual sizes above the minimum landing size limit, and a fairly constant exploitation rate at low levels that did not exceed 25%, accompanied by relatively constant CPUE values through time. Temporal variations in unit price and revenues per unit of effort showed higher values after EAF/Co-M implementation. These indicators, taken together, suggest that the enhanced production capacity of the fishery during the EAF/Co-M implementation did not have a negative impact on the stock. The number of fishers involved in the activity has not changed markedly through time, but two remarkable positive changes occurred in the composition of the group: (i) an increasing number of licenses allocated twice in a row through time, which suggests the consolidation of a stable group of fishers; and (ii) a significant increase in the number of women directly involved in the fishing activity. This study provides solid empirical evidences to the idea that EAF, coupled with Co-M as a formal governance mode, could be helpful to address management tasks and to improve social-ecological conditions of SSFs. © 2015 Elsevier Ltd.


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.


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.

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