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Approximately half of the world's ice‐free ocean coastline is composed of sandy beaches, which support a higher level of recreational use than any other ecosystem. However, the contribution of sandy beaches to societal welfare is under increasing risk from local and non‐local pressures, including expanding human development and climate‐related stressors. These pressures are impairing the capacity of beaches to meet recreational demand, provide food, protect livelihoods, and maintain biodiversity and water quality. This will increase the likelihood of social–ecological collapses and regime shifts, such that beaches will sustain neither the original ecosystem function nor the related services and societal goods and benefits that they provide. These social–ecological systems at the land–sea interface are subject to market forces, weak governance institutions, and societal indifference: most people want a beach, but few recognize it as an ecosystem at risk. [ABSTRACT FROM AUTHOR]

Abstract: The global fisheries crisis has critical socioeconomic impacts on small-scale fisheries. In addition, the crisis also exacerbates the conflicts and technological interdependencies between artisanal and industrial fisheries. In the coastal zone of Uruguay, both the artisanal and the industrial fleet target the whitemouth croaker Micropogonias furnieri (Desmarest, 1823). In this paper, we assess the spatial dynamics of the artisanal fleet and evaluate technological interdependencies with the industrial fleet. To this end, information gathered from logbooks, vessel monitoring systems and monthly landing reports for five consecutive years was analyzed using a Geographic Information System (GIS). An Index of Fisheries Interdependencies (IFI) was developed to identify and measure the intensity of spatial overlap between the fleets. A strong intra-annual displacement of the artisanal fleet was observed along the coast, as the fleet followed the migrations of the stock to the coastal spawning areas. The catches increased from April to July for both fleets, whereas an inverse trend was observed from October to January. This finding indicated the negative effects of the activities of the industrial fleet on the artisanal catches. Declining Catch per Unit Effort (CPUE) trends and high IFI scores were detected at nursery and spawning areas and suggest early warning signals of stock overexploitation. Artisanal exclusive-use zones and spatio-temporal management windows are recommended to decrease the potential interdependencies between fleets. [Copyright &y& Elsevier]

We tested to what extent mean sea surface temperature, geometric constraints in range size frequency distributions (the mid-domain effect) and geographical coastline distance to the equator are related to species richness of coastal Mytilidae and Ostreidae in the Pacific and Atlantic coasts of South America (excluding islands). The location and magnitude of the peaks in species richness, as well as the shape of the pattern, varied between oceans. Results were not biased by spatial autocorrelation, although strong multicollinearity among predictor variables was detected. However, these regional-extent regression models suggest differences in the causal factors that explain richness gradients of studied bivalves in South American coasts, most likely related to historical events such as the Southeastern Pacific Pleistocene mass extinction of bivalves. Our results reinforced the conclusion that there is no single best explanatory cause for the latitudinal gradient in species richness and showed that the correlative approach is not useful when predictor variables are strongly correlated. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the distribution, diversity, and conservation status of oysters around the Caribbean and Atlantic coasts of South America. It notes that the oyster species were rated according to their biological/ecological and socio-economic importance, and conservation status, and their population trends were associated to their habitat, overfishing, exotic species, and diseases. Among the species studied, Crarassostrea gasar, C. rhizophorae, and Ostrea puelchana were identified to have the highest priority in the ranking. It notes the need for standardized methodology to evaluate the status of oyster populations through the ecoregions. The study suggests that the allocation of territorial use rights for fisheries to fulfill management and conservation goals.

Sandy beaches line most of the world's oceans and are highly valued by society: more people use sandy beaches than any other type of shore. While the economic and social values of beaches are generally regarded as paramount, sandy shores also have special ecological features and contain a distinctive biodiversity that is generally not recognized. These unique ecosystems are facing escalating anthropogenic pressures, chiefly from rapacious coastal development, direct human uses — mainly associated with recreation — and rising sea levels. Beaches are increasingly becoming trapped in a ‘coastal squeeze’ between burgeoning human populations from the land and the effects of global climate change from the sea. Society's interventions (e.g. shoreline armouring, beach nourishment) to combat changes in beach environments, such as erosion and shoreline retreat, can result in severe ecological impacts and loss of biodiversity at local scales, but are predicted also to have cumulative large-scale consequences worldwide. Because of the scale of this problem, the continued existence of beaches as functional ecosystems is likely to depend on direct conservation efforts. Conservation, in turn, will have to increasingly draw on a consolidated body of ecological theory for these ecosystems. Although this body of theory has yet to be fully developed, we identify here a number of critical research directions that are required to progress coastal management and conservation of sandy beach ecosystems. [ABSTRACT FROM AUTHOR]

Demographic and life-history attributes of the yellow clam, Mesodesma mactroides, were analyzed along exposed sandy beaches of the Atlantic coast of South America, from Brazil (32°S) to Argentina (41°S), covering most of its geographical range (24-41°S). Population features varied markedly within this range and exhibited systematic geographical pat- terns of variation. Abundance and growth/mortality rates significantly decreased from northern (Brazil and Uruguay) to southern (Argentina) populations. Snapshot information at the edge of its northern geographical range suggests a large-scale unimodal distribution pattern. Northern populations also had an extended or quasi-continuous recruitment season, whereas Argentinean populations had seasonal recruitment that became negligible at the southernmost edge of the range (41°S). Maximum individual sizes increased nonlinearly with latitude. This result, when considered together with density patterns, provided the second large-scale evidence of scaling of population density to body size in a sandy-beach population. Lifespan increased with latitude, ranging between 3 and >7 years. Length frequency- distribution analysis revealed marked intra-annual growth patterns for two populations located 7° latitude apart. Variations in water temperature explained large-scale differences in the demography and population dynamics of the yellow clam, and the high plasticity over latitudinal gradients leads to an adjustment of the phenotype-environment relationship. Long-term studies in Uruguayan beaches suggest that wide population fluctuations are the result of intertwined forces of environmental, density-dependent, and human-induced factors operating together at different spatiotemporal scales. As this species with planktonic larvae is structured as a metapopulation, future studies should incorporate a number of hierarchical scales to better understand macroscale variations in demographic patterns and life-history traits. [ABSTRACT FROM AUTHOR]

Among the diverse sources of impact on sandy coasts, man-made freshwater flows and discharges of sewage effluents strongly modify environmental quality by changing salinity and nutrient regimes. However, sandy beaches, which occupy three-quarters of the world''s shoreline, have received relatively little attention concerning consequences of this human-induced disturbance on the structure and dynamics of resident fauna. This paper reports the spatial effects of a freshwater canal discharge (Canal Andreoni) on the habitat and resident macrobenthos of an exposed sandy beach through a combined analysis of communities, populations and the surrounding habitat in three sites defined by previous studies as undisturbed (Barra), moderately disturbed (Coronilla) and grossly disturbed (Andreoni). Andreoni showed significant lower values of salinity, beach width, swash width and slope. Abundance, biomass, species richness, diversity and evenness significantly decreased towards the source of disturbance and were significantly and positively correlated with spatial variations in salinity. Multiple regressions explained up to 36% of the variability, often resulting in models composed by only one significant predictor, salinity, which can be considered as an aggregate variable that carries itself with different simultaneous effects in the nearshore-surf zone environment. The cirolanid isopod Excirolana armata generally dominated all sites in abundance, but at significantly lower values in the grossly disturbed site. The suspension feeders Donax hanleyanus and Emerita brasiliensis, which were well represented at Barra and Coronilla, did not occur in Andreoni, where insects were the most commonly represented after E. armata. In addition, the number of species and abundance of polychaetes tended to decrease towards the canal mouth, with the exception of punctual pulses of abundance of Scolelepis gaucha at Coronilla. In terms of biomass, the isopod E. armata dominated at Andreoni and Coronilla, whereas the suspension feeders D. hanleyanus and E. brasiliensis dominated at Barra. It is concluded that artificial freshwater discharges could significantly influence the distribution, abundance and community attributes of the biota of sandy beaches, and that further study of these ecosystems should include human activities as important factors affecting spatial and temporal trends. The combination of natural experiments together with macrocosm field and microcosm laboratory experiments is also suggested as a rich research vein for detecting the extent of disturbances in sandy beaches. [Copyright &y& Elsevier]

The Rio de la Plata and the adjacent Atlantic Ocean are covered by the most significant amount of environmental cooperation in the Southwest Atlantic. There are joint agreements between Uruguay and Argentina and their institutions, and there is a long history of bi-national fisheries management and maritime traffic organizations. However, these agreements do not cover many other activity sectors that come under different jurisdictions and regulatory instruments. Documentary sources spanning 30 years have been used to describe the spatial extent and evolution of more than 30 activities (grouped into main clusters), as well overlaps and conflicts between them. The higher number and diversity of activities were found in the coastal zone, while fisheries and spatially-defined management measures were dominant in common waters and on the continental shelf. Transport/navigation and communication cables were the most common clusters along surface and sub-bottom linear routes, respectively. The different and overlapping use of the water column and across multiple jurisdictions were the cause of sectoral conflicts, such as between fisheries-transport or fisheries-submarine cables. Under a sector-by-sector analysis, and in the absence of a comprehensive planning environment, many of these conflicts are resolved, at best, by legal proceedings. There have been significant advances in the governance and spatial organisation of fisheries and transport, while progress in conservation and infrastructure has not occurred at the same speed or by considering a broader vision of the system. Addressing the existing and increasing interferences or unresolved conflicts emphasises the need to consolidate multilevel governance frameworks and opportunities in order to advance in marine spatial planning in the Southwest Atlantic Ocean. [Display omitted] • Long-term and spatial changes in the use of marine space are assessed in Uruguayan waters. • 34 activities were mapped, with higher number and diversity in the coastal zone than offshore. • Interferences and conflicts between activities were assessed by combining maps, conflict scores and regulations. • Overlaps and interferences were found in clusters Transport, Fisheries and Cables and pipelines. • Suggestions are made to develop multilevel marine spatial planning, including shared waters with Argentina. [ABSTRACT FROM AUTHOR]

Since the beginning of the fishing industry in Uruguay, a variety of fishing activities began, evolved, and expanded into the deeper waters of the Uruguayan marine territory. The purpose of this study was to identify and map the Uruguayan higher intensity fishing areas over a 58-year time span. The concept of métier was used, which allows the grouping of fishing modalities according to target species, fishing units, gear and operation areas as descriptors for each activity. Information sources included published articles, reports, records in official publications, direct observations and research surveys conducted between 1960 and 2018 in the Río de la Plata and the Argentine-Uruguayan Common Fishing Zone. An overlapping model using a geographic information system was deployed in order to identify area use and intensity weighted by the number of fishing units. A total of 60 métiers were listed in two fleet segments, 25 artisanal métiers and 35 industrial métiers, throughout the analysed period. Currently, most métiers are inactive, and of those that are operational, most are the oldest métiers that are considered to be traditional fisheries. The overlap model showed higher activity spatially concentrated on the continental slope, in the eastern coastal zone and along the area near Montevideo, separated by fleet segment. Industrial activity showed an expansion of the area according to the number of métiers between 1995 and 2010. This analysis allowed us to quantify the geographical extent of fisheries in the long term, providing critical information for fisheries management and marine spatial planning. • The "Métier" concept was applied to fisheries between 1960 and 2018. • Sixty métiers were identified, including active and inactive, in two fleet segments. • The use of marine areas was different in small-scale and industrial fleet segments. • The area used by the industrial fleet expanded when the number of métiers reached the maximum. [ABSTRACT FROM AUTHOR]

The yellow clam Mesodesma mactroides is a cool-water species that typifies sandy beaches of the Southwestern Atlantic Ocean (SAO), which embraces one of the strongest ocean warming hotspots. The region is influenced by the Rio de la Plata (RdlP), which represents a zoogeographic barrier that restricts its larval exchange. We investigated yellow clam larval connectivity patterns using an individual based model (IBM). The IBM combined outputs from a 3D hydrodynamic model with a clam submodel that considered salinity- and temperature-dependent mortality for the planktonic larvae. Connectivity across the RdlP estuary occurred only for larvae released in spring during a strong La Niña event. Mortality due to freshwater precluded larval transport across the RdlP, whereas larval mortality induced by warmer waters reduced connectivity, leading to self-recruitment in most areas. Warming acceleration in this hotspot could further restrict larval connectivity between populations in the SAO, with conservation implications for this threatened species. • Mesodesma mactroides larval connectivity was studied through individual-based model. • 12-year ROMS outputs were used to address connectivity along Atlantic sandy beaches. • Connectivity across Rio de la Plata estuary occurred during a strong La Niña event. • Larval mortality due to warm water temperature reduced larval connectivity. • Warming acceleration could further restrict connectivity in this threatened species. [ABSTRACT FROM AUTHOR]