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We present an interdisciplinary review of the observed and projected variations in atmospheric and oceanic circulation within the southwestern South Atlantic focused on basin-scale processes driven by climate change, and their potential impact on the regional fisheries. The observed patterns of atmospheric circulation anomalies are consistent with anthropogenic climate change. There is strong scientific evidence suggesting that the Brazil Current is intensifying and shifting southwards during the past decades in response to changes in near-surface wind patterns, leading to intense ocean warming along the path of the Brazil Current, the South Brazil Bight, and in the Río de la Plata. These changes are presumably responsible for the poleward shift of commercially important pelagic species in the region and the long-term shift from cold-water to warm-water species in industrial fisheries of Uruguay. Scientific and traditional knowledge shows that climate change is also affecting small-scale fisheries. Long-term records suggest that mass mortalities decimated harvested clam populations along coastal ecosystems of the region, leading to prolonged shellfishery closures. More frequent and intense harmful algal blooms together with unfavorable environmental conditions driven by climate change stressors affect coastal shellfisheries, impact economic revenues, and damage the livelihood of local communities. We identify future modelling needs to reduce uncertainty in the expected effects of climate change on marine fisheries. However, the paucity of fisheries data prevents a more effective assessment of the impact of climate change on fisheries and hampers the ability of governments and communities to adapt to these changes. [ABSTRACT FROM AUTHOR]

In this study, we describe what we term a Blue Transition, defined as the passage from fish biomass reduction to recovery in exploited aquatic resources, enabled by aquaculture. A Blue Transition is a key component of emergent "blue" discourses which support that the expansion of aquaculture would relieve pressure on declining capture fisheries, thus contributing to global food security, particularly of the poorest populations. Based on global secondary data and the case of Chile, we explore the evidence of such claim and the implications of a Blue Transition for fisheries and aquaculture development. In 2012, worldwide aquaculture production surpassed wild captures; nevertheless, such turnaround would have not taken place without China's contribution. In Chile, this turnaround occurred in 2014, concurrently with the lowest industrial landings registered since the 1960s (1,227,359 tons). Chile's aquaculture is not relieving wild fisheries or satisfying food demands of the lower income population, in the country or elsewhere. Salmon, the main aquaculture product, is destined mainly to Japan, Russia and United States where, due to its high prices, it is consumed mostly by wealthy consumers. For the case at hand, evidence suggests that a blue transition may be underway but is going in the wrong direction: from what may have been sustainable fisheries management before the 1970s to the overexploited wild fisheries of today. [ABSTRACT FROM AUTHOR]

Abstract Sandy beaches are dynamic systems that host a diverse range of fauna whose habitat is controlled by the interactions among sand, waves and tides. In recent decades much of the study of sand beach ecology has focused on community type and structure across the range of beach types, as well as regional variations. In order to compare different studies, accurate information is required on the nature of the environment studied: sand particle size, tide range and wave conditions. Unfortunately this has not always been provided by beach ecologists. Our understanding of sandy beach processes has advanced to the stage where ecologists can no longer omit assessing the role of wave climate, even if this cannot be done precisely, as can be done for sand and tides. In this paper we provide a method to quantify wave conditions and, in combination with sand particle size and tide range, determine the beach type and state. For waves, we first highlight the concepts 'sea' and 'swell' as distinct from the terms 'sheltered' and 'exposed'; we then provide a method to estimate breaker height. We then develop a model with two steps: first, breaker height is combined with tide range to identify whether waves or tides are the primary driver of beach morphology and thereby the define the beach type (wave-dominated, tide-modified or tide-dominated); then, using breaker height, period and sand particle size, the beach state is determined. Seven main beach morphodynamic types-states are defined. At the narrow and steep extreme are wave-dominated reflective beaches and at the wide and low gradient extreme are tide-dominated flats. The physical and ecological features typical of the seven types-states are presented, as well as some management implications. Highlights • A simple method is provided to estimate breaking wave height. • The terms 'sea' and 'swell' are differentiated from 'sheltered' and 'exposed'. • A two-step model is developed to determine sandy beach type and state. • Seven types-states are defined and discussed, with examples. [ABSTRACT FROM AUTHOR]

Structural and functional changes in a sandy beach ecosystem in the southwestern Atlantic (Barra del Chuy, Uruguay) were assessed by contrasting four Ecopath trophic models and performing temporal dynamic simulations using Ecosim. Each model (1982, 1989, 1996 and 2012) represents a historical period of a clam fishery in which regulatory structure, management tools and resource status varied substantially. The results showed that this land-ocean interface experienced significant changes reflected at the population and ecosystem levels, owing to a combined effect of fishing and climate variability. Most system biomass (excluding phytoplankton and detritus) consisted of benthic invertebrates. Phytoplankton increased significantly over time, whereas the biomass of benthic macrofaunal components varied among the periods due to bottom-up processes, mass mortalities of the harvested clams and fishing intensity. Major fishing impacts on the targeted clam and mass mortalities occurred concurrently with low phytoplankton biomass, and clam recovery occurred in the absence of harvesting and increasing primary production. Ecosystem-level attributes (e.g., Total System Throughput, Ascendency) showed considerable temporal fluctuations, which were primarily related to changes in system productivity associated with a climatic shift from a cold phase to a warm phase and increasing onshore winds. An analysis of robustness and order showed an ecosystem state lacking the flexibility to adapt to new perturbations. Dynamic simulations showed the prominent bottom-up role of environmental variability on ecosystem function and structure. Temporal dynamics is conducted by changes in primary production forced mainly by temperature patterns. The concurrent role of climate variations and fishing explained the long-term dynamics of this ecosystem, suggesting that sandy beaches are fragile social-ecological systems whose services are increasingly threatened by long-lasting stressors. [ABSTRACT FROM AUTHOR]

Aim While geographical patterns of species richness are reasonably well explored for single well-studied taxa, less is known about aggregate patterns of total richness for major biomes and their environmental correlates. Here we analyse continental-scale aggregate patterns of macrofaunal diversity for sandy beaches, a dominant habitat along the Atlantic and Pacific coasts of South America. Location South American coastlines. Time period Present day (data amassed from studies performed since 1971). Major taxa studied Benthic macrofauna, including crustaceans, polychaetes and molluscs. Methods We compiled richness information for all macrofaunal groups on 263 sandy beaches in South America using standard criteria. We further matched these data with environmental variables including sea surface temperature (SST), chlorophyll a, grain size, beach slope, tide range and various morphometrics. We used generalized linear mixed models to relate environmental factors to observed variation in total macrofaunal richness across all beaches, testing competing hypotheses about environmental correlates and possible drivers of latitudinal diversity. Results Macrofaunal richness decreased from tropical to temperate beaches in the Pacific and followed a parabolic trend in the Atlantic, with the highest biodiversity found at tropical and mid-latitudinal bands. Beach slope, tidal range and chlorophyll a mostly explained latitudinal trends in macrofaunal richness, followed by grain size, SST and ocean basin. Main conclusions This study indicates that richness of macrofaunal species at a given beach is most closely related to characteristics of the physical habitat, such as beach slope, area and grain size. At this scale, planktonic food supply also appeared to be more important than temperature, which is a dominant explanatory variable of global-scale variation in species richness. [ABSTRACT FROM AUTHOR]

The systematic dwindling over time of many commercially important fish stocks in developed countries and the increasing demand of international markets provided a window of opportunity for fishery sector development in many developing countries. Science-based assessments of how market forces impact on fisheries trends are particularly limited in developing countries. This study assessed long-term trends (1960–2013) of the Uruguayan industrial fishery sector, including: (i) landings discriminated by species and resource type; (ii) variations in nominal effort and fleet capacity; (iii) bioeconomic patterns for most important species; and (iv) export and import volumes at the Uruguayan seafood market. Results indicate the sector underwent four phases that depict long-term patterns: development, expansion, stabilization-diversification and declining yields and market contraction. The development of the sector was mainly due to the Argentine hake fishery, which was characterized by a sustained increase in landings, nominal effort and fleet capacity during the initial decades, but showed a decreasing trend afterwards. In response, a fishery diversification policy based on more valuable target species but with lower trophic levels was developed. Uruguay adopted a seafood net exporter role since the very beginning, with exports increasing linearly through time. More recently, seafood imports, with more competitive prices than locally caught seafood, have been gaining ground in the domestic market, reaching a third of all seafood currently consumed. Nowadays, the Uruguayan fishery sector is facing a crisis that is clearly reflected in the decreasing yields of the main species targeted, exports dwindling and increasing seafood imports. These results highlight the pressing need of the industrial sector to shift its model of fisheries exploitation. This study also provides evidence of the need to consider additional bioeconomic analysis to fully understand the behavior of the fishery sector as a dynamic social-ecological system operating in a globalized seafood trade scenario. [ABSTRACT FROM AUTHOR]

The sandy beaches that fringe much of the world's oceans are the most sought-after venue for recreation and tourism on our home planet. However, the value of sandy shores goes well beyond simple recreation, fun and enjoyment. The social-ecological system comprising the sandy littoral zone has diverse intrinsic values, not just in ecosystem services and as repositories of biodiversity, but also as part of our spiritual and cultural world. In this essay we aim to highlight the inherent beauty of sandy littoral zones as a whole and beaches in particular, through the eyes of celebrated poets. We explore the timeless fascination that beaches have held for people and their immense value in spiritual, cultural, economic and environmental contexts. We touch briefly on how beaches are threatened today by a variety of stressors, which are driven primarily by anthropogenic influences. We draw attention to the requirement to consider the sandy littoral holistically and include the beach, dunes and surf zone, which are tightly coupled systems. Then we conclude by emphasising the need for farsighted and participatory governance that should manage the entire sandy littoral as a whole and be underpinned by sound science. We hope that this essay will promote greater appreciation of sandy beaches and stimulate research focused on providing direction to coastal planning and management, as well as encouraging custodians of the coast to consider a more participatory approach to governance. [Display omitted] • Sandy beaches hold a timeless fascination and are the most sought-after recreation venue on our planet. • Beaches provide several ecosystem services to people over and above recreation. • Beaches face coastal squeeze, being constricted between rising sea level and encroaching development. • The future of these ecosystems depends on adaptive and participatory governance based on sound science. [ABSTRACT FROM AUTHOR]

The deep-sea crab Chaceon notialis is distributed along the continental shelf and slope of the SW Atlantic Ocean, mainly in Uruguayan waters, supporting a male-only fishery of high commercial value since 1993. A long-term study of catch per unit of effort (CPUE), population structure and individual weight was carried out before and after the onset of exploitation. Some 23,000 individuals were collected at 300–900 m depth and between latitudes 35°00′ and 36°40′S during seven fishery-independent trap surveys. Additional data on weight and individuals with signs of molting were gathered from 1000 to 1600 m south to 37°00′S after the start of the fishery. Individual weight decreased markedly over time, particularly after the start of the fishery, and decreased with depth for both sexes, with opposite patterns with latitude. CPUE peaked at 900 m and 35°40′S and remained stable over time, suggesting that it does not reflect the condition of the stock. Ovigerous females were found between 300 and 500 m and in the northernmost edge of the distribution range (35°00′S–35°40′S). The number of females decreased exponentially with depth and linearly with latitude. Molting males and females followed opposite latitudinal patterns, with highest percentages of molting individuals found between 600 and 900 m depth. A spatial management framework is proposed, which includes closing areas to fishing where ovigerous females, juvenile crabs and largest males are concentrated. [ABSTRACT FROM AUTHOR]

Ecosystem engineers can modify the environment, affecting the associated community. Studies of mussels as ecosystem engineers have been conducted mostly in the rocky intertidal zone, while those in sedimentary intertidals have been relatively scarce. The present study assessed the effect of varying densities of Brachidontes rodriguezii on local environmental variables (substrate weight, water content, organic matter, weight of sediments adhering to mussel byssus) and ecological attributes of the associated community (richness, abundance, diversity, evenness, and assemblage structure) at different intertidal levels, sites, and seasons, in a mixed-sediment intertidal region in San Antonio Bay (Patagonia, Argentina). We performed two independent manipulative field experiments at low and mid intertidal levels at two sites -Punta Verde (PV), with relatively higher current velocities and coarser grain sizes than Punta Delgado (PD)- in both winter and summer. Manipulative experiments consisted in reducing mussel density to 50% in the low intertidal and increasing that density to up to 100% in the mid zone. We hypothesized that local environmental variables and ecological attributes associated with B. rodriguezii depended on mussel density. The reduction in B. rodriguezii density increased the evenness and reduced the abundance at PD plus reduced the richness at PV. Also, when reducing mussel density, the assemblage structure differed in water content and organic matter at both sites between treatments and seasons. The sediment weight adhering to mussel byssus in PD and substrate weight in PV were the best descriptors of the assemblages. The increase in mussel density, however, produced a weak effect on the ecological attributes of the community, and the assemblage structure did not correlate with the environmental variables considered. Our results demonstrated a stronger engineering effect of B. rodriguezii at reduced, but not increased, mussel density. This study revealed that the ecological attributes associated with B. rodriguezii both were density-dependent and varied with sites along the year in mixed-sediment intertidal zones. • Manipulative experiments showed an engineering effect of the mussel B. rodriguezii. • Increasing and reducing the mussel-density modified the local environmental variables. • Manipulation of the mussel density affected the evenness, abundance and richness. • This effect was stronger in the low than in the mid-intertidal level in both sites. • The assemblage structure was explained by some environmental variables. [ABSTRACT FROM AUTHOR]

Co-management (Co-M), defined as the sharing of management tasks and responsibilities between governments and local users, is emerging as a powerful institutional arrangement to redress fisheries paradigm failures, yet long-term assessments of its performance are lacking. A comparative analysis of five small-scale Latin American shellfisheries was conducted to identify factors suggesting success and failure. In Chile, Uruguay and Mexico Co-M produced positive effects, including stabilization of landings at low levels, increase in abundance, CPUE, unit prices and revenues per unit of effort, and reduced interannual variability in several fishery indicators, particularly in landings. Co-M was successful because it was mainly bottom-up implemented and accompanied by-catch shares (spatial property rights and community quotas). By contrast, Co-M implementation was unable to prevent the collapse of the Galapagos sea cucumber fishery, as reflected by a decrease in abundance and CPUE. Negative effects were also observed in the Galapagos spiny lobster fishery during Co-M implementation. However, recovery was observed in recent years, reflected in a stabilization of fishing effort and the highest CPUE and economic revenues observed since the beginning of the Co-M implementation phase. The combined effects of market forces, climate variability and a moratorium on fishing effort were critical in fishery recovery. We conclude that Co-M is not a blueprint that can be applied to all shellfisheries to enhance their governability. These social-ecological systems need to be managed by jointly addressing problems related to the resources, their marine environment and the people targeting them, accounting for their socioeconomic and cultural contexts. [ABSTRACT FROM AUTHOR]

Small-scale fisheries (SSFs) are social-ecological systems that play a critical role in terms of food security and poverty alleviation in Latin America. These fisheries are increasingly threatened by anthropogenic and climatic drivers acting at multiple scales. We review the effects of climate variability on Latin American SSFs, and discuss the combined effects of two additional human drivers: globalization of markets and governance. We show drastic long-term and large-scale effects of climate variability, e.g., sea surface temperature anomalies, wind intensity, sea level, and climatic indices, on SSFs. These variables, acting in concert with economic drivers, have exacerbated stock depletion rates in Latin American SSFs. The impact of these drivers varied according to the life cycle and latitudinal distribution of the target species, the characteristics of the oceanographic systems, and the inherent features of the social systems. Our review highlights the urgent need to improve management and governance systems to promote resilience as a way to cope with the increasing uncertainty about the impacts of climate and globalization of markets on Latin American SSFs. [ABSTRACT FROM AUTHOR]

Abstract: Global patterns in species richness in sandy beach ecosystems have been poorly understood until comparatively recently, because of the difficulty of compiling high-resolution databases at continental scales. We analyze information from more than 200 sandy beaches around the world, which harbor hundreds of macrofauna species, and explore latitudinal trends in species richness, abundance and biomass. Species richness increases from temperate to tropical sites. Abundance follows contrasting trends depending on the slope of the beach: in gentle slope beaches, it is higher at temperate sites, whereas in steep-slope beaches it is higher at the tropics. Biomass follows identical negative trends for both climatic regions at the whole range of beach slopes, suggesting decreasing rates in carrying capacity of the environment towards reflective beaches. Various morphodynamic variables determine global trends in beach macrofauna. Species richness, abundance and biomass are higher at dissipative than at reflective beaches, whereas a body size follows the reverse pattern. A generalized linear model showed that large tidal range (which determines the vertical dimension of the intertidal habitat), small size of sand particles and flat beach slope (a product of the interaction among wave energy, tidal range and grain size) are correlated with high species richness, suggesting that these parameters represent the most parsimonious variables for modelling patterns in sandy beach macrofauna. Large-scale patterns indicate a scaling of abundance to a body size, suggesting that dissipative beaches harbor communities with highest abundance and species with the smallest body sizes. Additional information for tropical and northern hemisphere sandy beaches (underrepresented in our compilation) is required to decipher more conclusive trends, particularly in abundance, biomass and body size. Further research should integrate meaningful oceanographic variables, such as temperature and primary production, in deciphering latitudinal trends. [Copyright &y& Elsevier]

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]

Abstract: Exposed marine beaches are physically rigorous habitats in which macrofaunal patterns have been well correlated with physical factors. In this context, the habitat safety hypothesis (HSH) predicts an increase in abundance of supralittoral species from dissipative to reflective conditions in microtidal oceanic beaches. However, the HSH has not been adequately tested in estuarine sandy beaches. Here, we build a predictive model based on the supralittoral talitrid amphipod Atlantorchestoidea brasiliensis that allowed us to test the HSH along a macroscale estuarine gradient. Fifteen Uruguayan sandy beaches along a salinity gradient (from 0.1 to 34.3) generated by the Río de la Plata estuary (SW Atlantic Ocean) were sampled over a two-year period. A conditional two-step procedure using a General Additive Model (GAM) was performed in order to model A. brasiliensis occurrence (1st-step) and abundance (2nd-step), based on a comprehensive set of environmental variables [salinity, water temperature, beach face slope (BFS), mean grain size, wave height and sand compaction, moisture and organic matter]. Each GAM was parameterized using generalized linear models (GLMs). An external validation procedure was used. Data were divided randomly into training (75%) and test (25%) sets. The 1st-step GAM/GLM retained 5 physical descriptors in the model (decreasing order of importance): wave height, salinity, BFS, organic matter and sand compaction. The 2nd-step GAM/GLM retained 6 physical descriptors: sand compaction, water content, salinity, wave height, water temperature and organic matter. The predictive ability of these models and the resulted combined model, as well as their external validity, was highly significant and supported the predictions of the HSH. However, the highest and lowest abundances were observed, respectively, on reflective and dissipative beaches in the outer estuary; i.e., the predictions based on the HSH did not account for the high levels of abundance observed on these beaches compared with oceanic ones. Therefore, the HSH was expanded to include microtidal estuarine beaches. [Copyright &y& Elsevier]

Phylogenetically related species share attributes that lead to common responses to environmental conditions, but which could also produce the exclusion of species by its relatives. These processes could generate the patterns of phylogenetic attraction or repulsion in local communities, where related species would tend to coexist more or less than expected by chance. This paper aims to (1) analyse the phylogenetic structure of a benthic gastropod assemblage in the south-western Atlantic Ocean (SAO); (2) explore the linkages between phylogenetic structure and spatial distribution patterns; (3) compare outcomes driven by the analysis of presence-only data and predictive species distribution models; and (4) explore which aspects of the gained knowledge can be useful to the design of sound conservation and/or management actions. Uruguayan shelf and slope in the SAO. Spatial patterns in taxonomical relatedness were assessed using (1) raw presence/absence data (i.e. realized niche approach) and (2) reconstruction of the potential composition of the assemblage from niche modelling (i.e. fundamental niche approach). Null models were used to test hypotheses on assemblage structure. Significant departures from the null hypothesis that all species were drawn from the same assemblage were observed irrespectively of the approach, indicating the existence of non-random structures. However, a high proportion of local communities can be thought as random subsets of the regional species pool. This lack of a strong signal of a taxonomic effect could be related to the absence of a linkage between taxonomic distances and ecological similarities. Our results suggest a random assembly of local communities from the regional species pool and/or niche filtering independent of phylogeny as main determinants of local community composition. We also suggest that local assemblages displaying significantly higher (or lower) than expected taxonomic relatedness should be taken into consideration for designing spatially explicit conservation measures. [ABSTRACT FROM AUTHOR]

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]

Abstract: We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world''s single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical–biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders. [Copyright &y& Elsevier]

Ovarian macroscopical analysis, histological validation and field sampling procedures were used to evaluate the variability in reproductive traits of the mole crab Emerita brasiliensis Schmitt, 1935 (Decapoda: Hippidae) in two exposed sandy beaches of Uruguay with contrasting morphodynamics. All developmental stages involved in the complex life cycle exhibited lower abundance, individual size and temporal occurrence in a harsh reflective beach, compared with a more benign dissipative environment. In addition, this population showed more compressed events of the reproductive cycle (e.g oogenesis, encounter of potential mate and female parental care) and recruitment period. However, the beginning of the vitellogenesis, ovary maturity, male sexual differentiation and ending of spermatogenesis occurred at smaller sizes under dissipative conditions. These results disagree with the recent findings of delayed sexual maturity in dissipative beaches. We postulate that, in dissipative conditions, high food availability might allow an overlapping of reproductive and moulting processes, and thus females may reach optimum size and sexual maturity with fewer moults than in reflective beaches. Hence, reproductive responses must be considered not only in relation to environmental harshness, but also in the context of life history traits and their phylogenetic and allometric constraints. [ABSTRACT FROM AUTHOR]

Microscopic analysis and field sampling procedures were used to compare demographic and reproductive strategies of the intertidal wedge clam Donax hanleyanus (Bivalvia: Donacidae) in two exposed sandy beaches with contrasting morphodynamics (reflective vs. dissipative) during 13 consecutive months. Histological analysis showed that: (1) the reproductive cycle of D. hanleyanus was more extended in the dissipative beach, and this was true for all the three pre-active (beginning of gonadal activity), active (maturation) and spawning stages; and (2) males and females showed significantly smaller sizes at sexual maturity at the reflective beach. Even though successive increments in proportion and mature at size were observed, the sigmoid function was significantly steeper at the reflective Arachania for both sexes, suggesting an abrupt transition to maturity. Field sampling revealed a more extended recruitment period at the dissipative beach, where recruits were also significantly more abundant than at the reflective beach. These results give support for the habitat harshness hypothesis, which predicts that in intertidal species capable of sustaining populations across a wide spectrum of physical conditions, such as D. hanleyanus, abundance, recruitment, size at maturity and extent of reproductive and recruitment seasons increase from reflective to dissipative beaches. However, a recent hypothesis suggests that reflective beaches acting as sink populations were not sustained, because mature and spawning individuals of both sexes were found in the reflective beach throughout the study period. Thus, we suggest that post-settlement processes are critical in modulating population patterns for this bivalve. [ABSTRACT FROM AUTHOR]

The habitat harshness hypothesis (HHH) postulates that in reflective beaches the harsh environment forces organisms to divert more energy towards maintenance and they therefore have lower abundance, fecundity, growth and survival rates than in dissipative beaches. Recent investigations have tested this hypothesis through single comparisons of only two beaches, and thus the observed trends in population level variables cannot be attributed incontestably to the beach state, but only to location. Here, abundance, reproduction, recruitment, population structure and body size of the intertidal mole crab Emerita brasiliensis were compared between populations from eight microtidal exposed sandy beaches with contrasting morphodynamics, sampled bimonthly during 22 months throughout the 180 km Uruguayan Atlantic coast. Physical variables and compound indices of the beach state were used to categorize sandy beaches. The results of this bi-annual large-scale analysis were fully consistent with the predictions of the HHH: abundance (total and population components), duration of the reproduction and recruitment seasons and the individual size of megalops and females of the mole crab E. brasiliensis decreased from dissipative to reflective beaches. This was reflected by linear or, mostly, nonlinear relationships between biological and both physical variables and compound indices of beach state. In conclusion, this multi-beach sampling provides compelling evidence of a consistent response of demographic and life history traits of an intertidal beach species to morphodynamic characteristics. [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]

Abstract: Salinity has been identified as a key variable affecting the distribution of aquatic organisms and influencing critical physiological processes. In sandy beach environments, variations in salinity resulting from local freshwater discharges have shown to produce dramatic effects in the habitat and the resident macrofauna. However, macroscale effects of salinity on sandy beach macrofauna have not been assessed yet. Here, we describe large-scale (400km) variations in species richness and abundance along a full salinity gradient generated by the Río de la Plata estuary in the south-western Atlantic Ocean. Two-year data assembled from 16 Uruguayan sandy beaches spanning a continuum from reflective to dissipative states were used to model variations in species richness and abundance as a function of salinity and beach morphodynamics. Environmental variables were highly correlated, showing a strong increase (linear or nonlinear) in swash/beach width, wave height and wave period towards oceanic beaches. The association between mean salinity and salinity range was best explained by a quadratic relationship, meaning highest variability at intermediate salinities (14–24). Species richness clearly increased with salinity, swash width and the compound index of beach state Ω (Dean''s parameter), and markedly decreased with salinity range and beach face slope. A multiple stepwise regression model that explained 89% of the variance in species richness, included salinity range and beach width as the most important predictor variables. Total abundance increased from estuarine to oceanic beaches and from reflective to dissipative ones. Multiple regression analysis incorporated five environmental variables as main predictors: in addition to salinity range, the model included grain size, sorting, penetrability and organic matter content of the sediment. We conclude that salinity variability is a key factor affecting sandy beach morphodynamics and shaping macroscale patterns in species richness. Alternatively, concurrent variations in salinity and sedimentological variables shape the spatial distribution of total abundance in sandy beach macrofauna. [Copyright &y& Elsevier]

The influence of environmental (temperature, salinity, aquatic vegetation) and density-dependent (abundance of recruits) factors on growth and mortality of four Farfantepenaeus species were evaluated during their period of estuarine residence, through a 2-year field study at Celestun lagoon, Mexico. Growth rates of the three most abundant species (F. brasiliensis, F. duorarum, F. notialis) were positively related with temperature and aquatic vegetation biomass, whereas some significant relationships between environmental factors and mortality rates were also demonstrated. Our results suggest that density-dependent processes regulate growth and mortality in these shrimp populations. Density-dependent mortality was also suggested by a strong compensatory relationship between recruits and juveniles. We conclude that population dynamics of Farfantepenaeus shrimps during their estuarine phase seem to be driven by the combined forces of density-dependent and environmental factors operating together. [ABSTRACT FROM PUBLISHER]

Biogeographic patterns in life history traits of the Pan-American sandy beach isopod Excirolana braziliensis were analyzed to determine latitudinal variations along its distribution, from tropical (9°N) to temperate (39°S) sandy beaches in Atlantic and Pacific oceans. Population features exhibited systematic geographical patterns of variation: (1) an increase in individual sizes and growth rates towards temperate beaches, following an inverse relationship with mean water temperature of the surf zone; (2) a shift from almost continuous to seasonal growth from subtropical to temperate Atlantic beaches and a positive relationship between amplitude of intra-annual growth oscillations and temperature range; (3) a linear decrease in life span and an increase in natural mortality from temperate to subtropical beaches; and (4) an increase in the individual mass-at-size (length–mass relationship) from subtropical to temperate beaches. Analyses discriminated by sex were consistent with the patterns illustrated above. Local effects of temperature and beach morphodynamics are discussed. Our results demonstrate that the population dynamics of E. braziliensis is highly plastic over latitudinal gradients, with large-scale variations in temperature and concurrent environmental variables leading to an adjustment of the phenotype–environment relationship. [Copyright &y& Elsevier]

Demographic and life-history attributes of the mole crab Emerita brasiliensis were analysed along 2700 km of the Atlantic coast of South America, including sandy beaches at the southernmost limit (Uruguay) and at the core of its geographical range (Brazil). Population features varied markedly within this range and exhibited systematic geographical patterns of variation. Abundance significantly increased from temperate to subtropical beaches, and the same held true for the asymptotic weight of males. Conversely, length at maturity and asymptotic weight of females increased from subtropical to temperate beaches, being inversely related to sea water temperature. Macroecological patterns in abundance and body weight showed the first large-scale evidence of scaling of population density to body size for a sandy beach population. Mortality rates (both sexes) followed a nonlinear increase from low-density temperate beaches to high-density subtropical beaches. The effect of habitat quality and availability could explain discontinuities in the species distribution within its range, and also differential responses in life-history attributes at a local scale. Asymmetries and converse latitudinal trends between sexes suggest that there is not a single general factor determining large-scale patterns in life-history traits of this species. Our results reinforce the view that density-dependent and environmental factors operating together regulate sandy beach populations. The need to develop macroecological studies in sandy beach ecology is highlighted, as knowledge acquired from local to large spatial scales throws light on population structure and regulation mechanisms. [ABSTRACT FROM AUTHOR]

This paper develops a precautionary bioeconomic approach for the red grouper (Epinephelus morio) multi-fleet fishery in the Campeche Bank, Gulf of Mexico, based on a long-term analysis covering the years 1980–2000. Population structure was estimated through commercial sampling of the three fishing fleets participating in the fishery: two Mexican (one artisanal and the other industrial) and one Cuban (industrial). Length frequency distributions (LFDs) did not show significant differences between the Mexican industrial and the Cuban fleets, but differed from those of the artisanal fishery, which targets smaller individuals. The lack of differences in the LFDs between years suggests that the population structure was stable during the last two decades. However, the instantaneous coefficient of total mortality Z, estimated through length-converted catch curves, significantly increased during the 21-year period of analysis, being in average 1.22 times higher in 2000 than in 1980. Annual estimates of yield and Z, together with unit costs of effort and ex-vessel prices, were used as inputs to build a bioeconomic yield–mortality model. A sensitivity analysis was performed under three scenarios of natural mortality M (0.16, 0.25 and 0.35 per year). The yield at maximum economic yield (YMEY) and the associated mortality levels ZMEY and FMEY were always the most conservative bioeconomic reference points (BRPs). The yield at maximum biological production (YMBP), YMEY and mortality-related BRPs were substantially lower than those based on maximum sustainable yield (MSY), thus constituting useful target BRPs for precautionary management. The bootstrap method used for determining the uncertainty associated at BRPs, shows that the best targets BRPs were YMEY and YMBP, whereas MSY is confirmed as a risky and limit BRP. A simple approach to the formulation of risk-averse management strategies was explored using the percentiles of cumulative distributions of MSY, YMBP and YMEY estimates generated from bootstrap against Z. We conclude that the red grouper fishery at Campeche Bank is overexploited and that immediate management actions are needed to prevent stock collapse. [Copyright &y& Elsevier]

The spatial structure and seasonal changes of estuarine fish assemblages in the Cie´naga Grande de Santa Marta (CGSM) were analysed based on four seasonal comprehensive surveys conducted in 1993–1994 and 1997. Geostatistical and multivariate techniques were used to: (a) determine seasonal changes in spatial distribution of the species richness, and (b) identify assemblages of estuarine fish and their relation to abiotic factors. Potential biotic interactions affecting the assemblage structure were also explored. A total of 11075 individuals representing 39 species were collected, with Eugerres plumieri, Diapterus rhombeus, Micropogonias furnieri, Mugil incilis, Cathorops spixii, Elops saurus and Anchovia clupeoides as dominant species between seasons. Spatial distribution of fish richness differed between rainy and dry seasons in each year, whereas species mapping showed spatial patchiness in 1993–1994 and gradients during 1997. Strong evidence of species saturation was found in all seasons, suggesting biotic interactions limiting species richness at a threshold density of ca. 50 ind./5000 m2. Marine, marine-estuarine and freshwater species were classified in each season according to their capability to cope with salinity fluctuations. Associations defined by functional feeding guilds were also identified. Empirical and statistic evidence showed that fish assemblages differed between seasons within each year, and each assemblage was always dominated by a small number of species, notably E. plumieri in both years 1993–1994 and 1997. Between-season differences in fish assemblage structure in the CGSM seem to be driven by abiotic factors; however, evidence of species saturation could suggest the existence of density-dependent factors operating together. [Copyright &y& Elsevier]

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]

We demonstrated through a 2-year field study that mortality rates of juvenile shrimps Farfantepenaeus duorarum in a coastal lagoon from the Gulf of Mexico decrease as the individual size increases. The size-dependent mortality was successfully modeled by a reciprocal function of length as well as by the conventional exponential decay model. The reciprocal model appears to provide a more reasonable prediction from a biological point of view, because the exponential model could underestimate mortality at smaller sizes. [Copyright &y& Elsevier]

We estimated the spatial population structure by size and the economical potential (biovalue) of a multispecies fish resource in an estuarine lagoon in Colombia, based on fishery-dependent (catch and effort) and independent (seasonal fishing surveys) data. Model-based (geostatistics, kriging) estimations of such performance variables were used to quantify the uncertainty in abundance, individual price by size and variable costs per haul. Monte Carlo analysis was used to assess the status of the fishery. The spatial dimension of risk analysis was explored by indicator kriging, whereas effects of biovalue on the spatial allocation of fishing effort were evaluated using contingency tables. Fish abundance, individual sizes and biovalue were spatially structured, but the spatial patterns varied between seasons and species. Analysis of biovalue showed a moderate risk that fishers had economic losses derived from the fishing activity. Spatial risk analysis showed that no more than 30% of the total area from the lagoon registered profitable levels of fish abundance, which affected the spatial allocation of fishing effort. Management implications supported by our study suggest seasonal and spatial fishing closures to protect juveniles and spawning stock of fish species. [Copyright &y& Elsevier]

A quantitative fishing survey of the scallop Zygochlamys patagonica was conducted in Uruguayan waters of the southwestern Atlantic Ocean in July 2001. The area surveyed extends between latitudes 35°50′S and 36°50′S, water depth ranging from 75 to 135 m. Stations were located systematically on parallel transects along the latitudinal gradient at 10-miles intervals and tows were set at every 5 m water depth interval. Stock estimates were obtained using geostatistics (kriging). This model-based approach showed a persistent spatial structure of the scallop population, as denoted by the spherical model fitted to both the whole population and the harvestable stock (individual height>55 mm). The structure of spatial dependence suggests a latitudinal structured process close to 48 km (total population) and 61 km (harvestable stock). Mean kriged density for the most likely value of gear efficiency (e=0.35) was 0.0122 and 0.0089 kg m−2 respectively, whereas global biomass estimated by block kriging were 48 039 and 35 246 t. Further analysis conducted at the bed of highest scallop densities provided additional support to the spatially structured process observed at a macroscale. Sensitivity analysis conducted with gear efficiency (e), revealed consistency of estimates with accepted theory, i.e., density and biomass estimates increased with decreasing e. Most of the life history traits of Z. patagonica showed clear large scale patterns: (1) concerning latitude, the highest density patch was found at the middle (36°20′S: mean=0.0279 kg m−2) of the surveyed area, whereas the southern border (36°50′S: mean=0.0204 kg m−2) had densities 16 times higher than the northern one (35°50′S: 0.0013 kg m−2). Muscle weight also increased linearly towards higher latitudes, whereas the harvestable stock, mean individual height and maximum height increased asymptotically in the NE–SW direction. Only muscle yield, either as global mean or discriminated by scallop size, significantly increased at the northern end of species distribution. (2) Bathymetric analysis showed a clear maximum density at depths close to 100 m, coinciding with the minimum proportion of harvestable stock, and a consistent inverse relationship between depth and (a) individual height and (b) muscle weight. Guidelines are suggested for fishery planning and development, taking special emphasis on the applicability of spatially explicit management tools. [Copyright &y& Elsevier]

We analyze intra and inter-annual harvesting patterns of the black escolar Lepidocybium flavobrunneum (Gempylidae), an important component of the incidental catch of the Uruguayan tuna fleet (UTF) at the southwestern Atlantic Ocean (SAO), based on daily information of catch, fishing effort and individual weight of all the specimens caught during 16 years (1981–1996). The analysis also compares the activities of two fishing fleets that operated in two different periods of fishery development: category A, which comprises Japanese vessels that operated between 1981 and 1991, and category B, consisting of American and Spanish vessels that operated between 1992 and 1996. The relative representation of the total incidental catch significantly increased during the 16-year period of activity of the UTF, reaching 43% of the total catch in 1995. A recurrent seasonal pattern in fishing effort, catch and catch per unit of effort (CPUE) was observed, peaking in austral winter and spring. The daily number of hooks and total catch were significantly higher for category A, which exerted 2.7 times higher number of hooks and obtained catches 3.33 times higher than category B. Differing with the above trends, mean daily CPUE of a category B vessel was 16% higher than category A, which can be attributed to the increase of fishing power. The mean individual weight decreased almost 40% in 15 years, i.e., from 23.2 kg in 1982 to 14.1 kg in 1996, suggesting overexploitation risks of this incidental species. The effect of increasing fishing power and the effectiveness of management measures for large pelagics at the SAO are discussed. [Copyright &y& Elsevier]

Over the last three decades, the advent and the continuous sophistication of telemetry devices have revolutionized our understanding of how pelagic sharks move and exploit their three-dimensional underwater habitat, with implications for management and conservation. In this study, conventional (4,648) and electronic (18) tags were used to assess the horizontal and vertical movements of blue sharks, Prionace glauca, and their vertical overlap with shallow and deep-set longline fishing gears in the southwestern Atlantic Ocean. Results revealed prolonged permanence in the area, large-scale displacements, including trans-equatorial, trans-Atlantic and Indian–Atlantic movements, and high daily displacement rates. Blue sharks showed an extensive use of the water column and considerable variability among and within individuals in vertical behavior, involving normal and reverse diel vertical migrations, surface-oriented behavior, extended use of mesopelagic waters, and occasional extreme dives into bathypelagic waters. Depth distribution appeared unrelated to size or sex but was influenced by the time of day and temperature, with deeper and colder temperatures consistently found during the day. The moon cycle affected the vertical distribution of some sharks but not others. Temperature-depth recorders deployed on hooks, combined with depth distribution from electronic tags, provided insightful information on the species' vertical overlap with shallow- and deep-set longline configurations. Encounterability values were higher during nighttime and lower during daytime for both longline configurations, but were largely affected by the individuals' vertical behavior, highlighting the importance of accounting for environmental conditions besides fishing gear configuration and métiers. This novel information on blue sharks' movements and fishery interactions in the South Atlantic Ocean can inform future management and conservation strategies. [ABSTRACT FROM AUTHOR]

The biophysical mechanisms influencing larval distribution and their impacts on the metapopulation dynamics of sandy beaches, particularly the connectivity patterns associated with larval dispersal, are poorly understood. Here, we identify larval connectivity patterns of the mole crab Emerita brasiliensis in the coast of Uruguay. A biophysical individual based model (IBM) of larval transport was coupled to a regional high-resolution physical model to estimate the monthly and interannual variation of larval connectivity, as well as the impact of the length of the reproductive period on it. Larval connectivity showed marked interannual variations, which were mainly related to interannual changes in seasonal winds and associated ocean circulation patterns, particularly during La Niña years. The southernmost area where E. brasiliensis occurs only received larvae from the nearest release area in November and January spawning events during a strong La Niña year, characterized by intense northeasterly winds. The Uruguayan coast constitutes the leading (poleward) edge of the distribution of E. brasiliensis , where climate change effects are projected to intensify. Extrapolation of these results to a climate change scenario with stronger La Niña events, suggest that larval transport to southernmost beaches will become more probable. • Emerita brasiliensis larval connectivity was studied through individual-based models. • 12-year ROMS outputs were used to address connectivity in the coast of Uruguay. • Connectivity changed drastically during La Niña event with intense northeasterly winds. [ABSTRACT FROM AUTHOR]

• State-of-the-art of sandy beach research is presented. • Local and global knowledge achievements and gaps are summarized. • Further research directions are indicated. [ABSTRACT FROM AUTHOR]

Abstract Sandy beaches comprise 31% of the ice free coasts of the world, providing a variety of ecosystem services essential to support human well-being, particularly protection against erosion and extreme climatic events. These highly dynamic environments are controlled principally by wave energy, tides and grain size, generating complex morphodynamic patterns that translate into strong area variation. Estimates of beach area and its variability are prime inputs for coastal management, a challenge that requires data representing a wide spatiotemporal scale. In this paper, a Landsat-based semi-automated methodology was developed to reconstruct the area of 21 sandy beaches of the Montevideo (Uruguay) coast from 1984 to 2016. This long-term information was also used to discern erosion-accretion cycles by means of wavelet analysis, and to explore the role of climatic forcing on these cycles through linear mixed models. A random forest classification algorithm was applied to Landsat images in order to estimate beach area. Long-term trends described a 27-year cycle with well-delimited quasi-decadal erosion and accretion phases related to climatic configurations. The beach area was negatively affected by an increase in sea level and climatic conditions of the previous year, being positively correlated with sea surface temperature anomalies and offshore winds (which favored accretion) and negatively correlated with onshore winds and intense El Niño Southern Oscillation (ENSO) events (favoring erosion). Our findings, together with the predicted increase in the occurrence and intensity of storms and extreme ENSO events, constitute a worrying scenario, as erosion in this populated coastal zone could have negative social, economic and ecological repercussions. The methodology developed here was useful to detect long-term changes in beach area and is entirely based on open-access information. Therefore, it is potentially applicable at any location on the planet. This approach is also useful to counteract the scarcity of long-term information that has precluded robust assessments of climate change effects on coastal zones. Highlights • Beach area was estimated through random forest classification on Landsat images. • Beach area estimations were based on open data and can be replicated elsewhere. • Sandy beach area showed a 27-year cycle, with defined erosion and accretion phases. • Erosion/accretion patterns in Montevideo beaches responded to climatic conditions. • Beach area model and IPCC predictions suggest an erosive scenario for this coast. [ABSTRACT FROM AUTHOR]

Highlights • Short-term fishery dynamics assessed by a community-based data collection program. • GLMMs used to model the contribution of environmental, socio-economic, and cultural factors. • Winds and red tides play a critical role in fishery dynamics. • CPUE of each fishing event affected by fisher attributes such as gender and age. • Adaptation strategies needed to counteract the increasing effects of external drivers. Abstract We assessed the relative contribution of a set of predictors on the short-term dynamics of the yellow clam intertidal fishery in Uruguay based on a community-based data collection program for five consecutive fishing seasons. Results of generalized linear mixed models showed that the occurrence of fishable days depends on the absence of red tide events and prevailing wind conditions, but also was related to the timing of each fishing event throughout the fishing season. Furthermore, higher fishing yields were coincident with the prevalence of northerly offshore winds. Catch per unit of effort levels of each fishing event were mostly related to interannual characteristics of each fishing season and, to a lesser extent, with fisher attributes (gender and age) and the timing of each fishing event. The adverse effect of red tides and unfavorable environmental conditions impose a high degree of uncertainty in this social-ecological system, leading to economic inefficiency. A key challenge for successful management of the yellow clam fishery and other similar small-scale fisheries relies in considering not only the resource and the governance subsystems, but also the dynamics of the resource users, together with relevant external drivers affecting them. [ABSTRACT FROM AUTHOR]

Unlike the advances generated on land, the knowledge of global diversity patterns in marine ecosystems is limited to a small number of studies. For sandy beaches, which dominate the world's ocean shores, previous meta-analyses highlighted the role of beach morphodynamics in explaining species richness patterns. Oceanographic variables and historical processes have not been considered, even though they could be main predictors of community structure. Our work, based on 256 sandy beaches around the world, analysed species richness considering for the first time temperature, salinity and primary productivity. Biogeographic units (realms, provinces and ecoregions) were used to incorporate historical factors in modelling processes. Ecoregions, which implicitly include isolation and coastal complexity among other historical geographic factors, best represented trends in species richness worldwide. Temperature was a main predictor of species richness, which increased from temperate to tropical sandy beaches. Species richness increased with tide range and towards wide beaches with gentle slopes and fine grains, which is consistent with the hypothesis that habitat availability has an important role in structuring sandy beach communities. The role of temperature and habitat availability suggests that ocean warming and sea level rise could affect the distribution of obligate species living in these narrow ecosystems. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor commenting on the article "Ecosystem-Based Fishery Management," by E.K. Pikitch, published in the July 16, 2005 issue.

Five catchment areas in Uruguay were selected to conduct a nutrient exportation analysis and to evaluate the effects of current land use on the eutrophication of coastal lagoons. Satellite images and national agriculture censuses were used for a quantitative analysis of land use changes from 1974 to 2005, and a nutrient export coefficient approximation was used to determine long-term changes in annual loads. Several eutrophication indicators (water, sediment and autotrophic communities) were assessed seasonally in the lagoon basins during 2005 and 2006. The areal annual load of nutrients exported to the lagoons increased over time. Population and extensive livestock ranching were the most important nutrient sources, while agriculture is increasing in importance. Buffer effects of riparian forests on eutrophication indicators were observed in contrast to the wetlands surrounding the lagoons, which seem to be acting as a source of nutrients. Catchment size was inversely related to most eutrophication indicators. Afforestation and agriculture were found not to directly impact eutrophication indicators, however, catchments with larger agricultural areas showed higher concentrations of suspended solids, which may indicate the export of particulate nutrients. Salinity was inversely related to most eutrophication indicators, suggesting that the manipulation of the sand bar of the lagoons is a critical management issue. Sediment-related eutrophication indicators were more sensitive to changes in land uses and covers, in contrast with the more variable water column indicators, suggesting their potential use as enduring indicators. This research provides a rapid and integral assessment for qualitatively linking catchment changes with eutrophication indicators in coastal environments, which can easily be replicated to track pollutants in locations that lack standardized monitoring programs needed for more complex catchment modeling approaches. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article “The Impact of Climate Change on the World's Marine Ecosystems,” by 0. Hoegh-Guldberg and J. F. Bruno in the June 18, 2010 issue.

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. [ABSTRACT FROM AUTHOR]

Most studies of sandy beach macrofauna have been restricted to semiterrestrial species and do not include insects when providing species richness and abundance estimates. Particularly, spatio-temporal patterns of community structure of the entomofauna inhabiting these ecosystems have been scarcely documented. This study assessed spatio-temporal distributional patterns of the night active entomofauna on a beach-dune system of Uruguay, including variations in species richness, abundance and diversity, and their relationship with environmental factors. A deconstructive taxonomic analysis was also performed, considering richness and abundance patterns separately for the most abundant insect Orders (Hymenoptera and Coleoptera) to better understand the factors which drive their patterns. We found clear temporal and across-shore patterns in the insect community inhabiting a land–ocean interface, which matched spatiotemporal variations in the environment. Abundance and species richness were highest in spring and summer, concurrently with high temperatures and low values of sediment moisture and compaction. Multivariate ordinations showed two well-defined species groups, which separated summer, autumn and spring samples from winter ones. Generalized Linear Models allowed us to describe a clear segregation in space of the most important orders of the insect community, with specific preferences for the terrestrial (Hymenoptera) and beach (Coleoptera) fringes. Hymenoptera preferred the dune zone, characterized by high elevation and low sand moisture and compaction levels, whereas Coleoptera preferred gentle slopes and fine and humid sands of the beach. Our results suggest that beach and dune ecosystems operate as two separate components in regard to their physical and biological features. The high values of species richness and abundance of insects reveal that this group has a more significant ecological role than that originally considered so far in sandy beach ecology. [ABSTRACT FROM AUTHOR]

Sandy ocean beaches are iconic assets that provide irreplaceable ecosystem services to society. Despite their great socioeconomic importance, beaches as ecosystems are severely under-represented in the literature on climate-change ecology. Here, we redress this imbalance by examining whether beach biota have been observed to respond to recent climate change in ways that are consistent with expectations under climate change. We base our assessments on evidence coming from case studies on beach invertebrates in South America and on sea turtles globally. Surprisingly, we find that observational evidence for climate-change responses in beach biota is more convincing for invertebrates than for highly charismatic turtles. This asymmetry is paradoxical given the better theoretical understanding of the mechanisms by which turtles are likely to respond to changes in climate. Regardless of this disparity, knowledge of the unique attributes of beach systems can complement our detection of climate-change impacts on sandy-shore invertebrates to add rigor to studies of climate-change ecology for sandy beaches. To this end, we combine theory from beach ecology and climate-change ecology to put forward a suite of predictive hypotheses regarding climate impacts on beaches and to suggest ways that these can be tested. Addressing these hypotheses could significantly advance both beach and climate-change ecology, thereby progressing understanding of how future climate change will impact coastal ecosystems more generally. [ABSTRACT FROM AUTHOR]

The yellow clam Amarilladesma mactroides (Reeve, 1854) inhabits the intertidal zone of sandy beaches along the temperate Atlantic coast from Brazil to Argentina (24°-41°S). Over the past decades, there has been a noticeable decline in its abundance, underscoring the importance of understanding their reproductive strategies and phenotypic plasticity for conservation efforts. This study explored large-scale variations in the size at first sexual maturity (SL 50), the age at maturity (A 50), the vitellogenic oocyte area (VOA), and a reproductive age index (RAI) that combines A 50 and the lifespan of each clam population, in relation to local habitat characteristics (e.g., beach morphodynamics) and large-scale environmental variables, such as salinity, sea surface temperature (SST) and chlorophyll- a. Four sandy beach clam populations from Uruguay and Argentina (latitudinal range: 33°45′S - 38°56′S) were sampled monthly between June and August during the reproductive season. SL 50 increased linearly with the mean and maximum SST (SSTmean, SSTmax), while VOA and RAI decreased with tidal range and width of intertidal zone, respectively. In beaches that had higher SSTmean and SSTmax, yellow clams reached maturity earlier and spent more than 70% of their lifespan in reproduction. The yellow clam population at the lowest latitude showed the largest oocyte sizes and a shorter lifespan of 3.5 years, while the population at the highest latitude had a longer lifespan (7 years) and the smallest VOA values. Populations at intermediate latitudes showed delayed sexual maturity, a 50–60% investment of their lifespan in reproduction, the longest lifespan (up to 9 years) and intermediate VOA values. The influence of the Rio de la Plata and Bahia Blanca estuaries modified the expected latitudinal gradient in reproductive traits, but local habitat conditions prevailed over large-scale environmental variables as explanatory factors of the reproductive strategy of the yellow clam. Therefore, the species displays phenotypic plasticity in its reproductive aspects to ensure population success. • Sea surface temperature explained between-beach differences in yellow clam maturity. • Estuaries modified the expected latitudinal gradient in reproductive traits. • Local factors prevailed over large-scale environmental ones in reproductive strategy. [ABSTRACT FROM AUTHOR]

Abstract: The food web structure of two sandy beach ecosystems with contrasting morphodynamics (dissipative vs. reflective) was examined using stable carbon (δ13C) and nitrogen (δ15N) isotope analysis. Organic matter sources (POM: particulate organic matter; SOM: sediment organic matter) and consumers (zooplankton, benthic invertebrates and fishes) were sampled seasonally in both sandy beaches. Food webs significantly differed between beaches: even though both webs were mainly supported by POM, depleted δ13C and δ15N values for food sources and consumers were found in the dissipative system (following the reverse pattern in δ13C values for consumers) for all the four seasons. Primary consumers (zooplankton and benthic invertebrates) use different organic matter sources on each beach and these differences are propagated up in the food web. The higher productivity found in the dissipative beach provided a significant amount of food for primary consumers, notably suspension feeders. Thus, the dissipative beach supported a more complex food web with more trophic links and a higher number of prey and top predators than the reflective beach. Morphodynamic factors could explain the contrasting differences in food web structure. The high degree of retention (nutrients and phytoplankton) recorded for the surf zone of the dissipative beach would result in the renewed accumulation of POM that sustains a more diverse and richer fauna than the reflective beach. Further studies directed to assess connections between the macroscopic food web, the surf-zone microbial loop and the interstitial compartment will provide a deeper understanding on the functioning of sandy beach ecosystems. [Copyright &y& Elsevier]

One billion people depend on seafood as their primary source of protein and 25% of the world's total animal protein comes from fisheries. Yet a third of fish stocks worldwide are overexploited or depleted. Using individual case studies, many have argued that community-based co-management should prevent the tragedy of the commons because cooperative management by fishers, managers and scientists often results in sustainable fisheries. However, general and multidisciplinary evaluations of co-management regimes and the conditions for social, economic and ecological success within such regimes are lacking. Here we examine 130 co-managed fisheries in a wide range of countries with different degrees of development, ecosystems, fishing sectors and type of resources. We identified strong leadership as the most important attribute contributing to success, followed by individual or community quotas, social cohesion and protected areas. Less important conditions included enforcement mechanisms, long-term management policies and life history of the resources. Fisheries were most successful when at least eight co-management attributes were present, showing a strong positive relationship between the number of these attributes and success, owing to redundancy in management regulations. Our results demonstrate the critical importance of prominent community leaders and robust social capital, combined with clear incentives through catch shares and conservation benefits derived from protected areas, for successfully managing aquatic resources and securing the livelihoods of communities depending on them. Our study offers hope that co-management, the only realistic solution for the majority of the world's fisheries, can solve many of the problems facing global fisheries. [ABSTRACT FROM AUTHOR]

We model and compare for the first time the ecosystem structure and trophic networks of two sandy beaches with contrasting morphodynamics (i.e. dissipative and reflective). To this end, an Ecopath model was implemented to represent the macroscopic food web on each sandy beach ecosystem. The dissipative beach model comprised 20 compartments and the reflective nine, including detritus, phytoplankton, zooplankton, benthic invertebrates, fishes and seabirds. Input data mainly came from direct surveys, whereas additional information was gathered from published and unpublished sources. Results revealed a major number of top predators and higher trophic levels (TLs) in the dissipative beach (seabirds, fishes, gastropods and the polychaete Hemipodus olivieri) than in the reflective one (fishes and Hemipodus olivieri). Detritivorous and filter feeding benthic invertebrates constituted intermediate trophic levels on both beaches. Exportation of most primary production and detritus was a common feature, with a detritivory:herbivory ratio of 0.42 in the dissipative beach and 0.51 in the reflective, indicating a higher utilization of the primary production in the former. The aggregation analysis showed five TLs in the dissipative beach and four in the reflective. Lower transfer efficiencies in the reflective beach could be attributed to a lower diversity of predators when compared to the dissipative system. Comparison of global ecosystem properties showed that the dissipative system had higher values for total system throughput, total biomass, net production, Ascendency and total number of pathways. We concluded that the greater diversity and biomass in the dissipative beach are reflected in a higher dimension and ecosystem organization than in the reflective beach, thus providing new evidences at the ecosystem level about well-established differences in biological descriptors between beach types. Finally, we stressed the need for acquiring experimentally-based information on benthic invertebrate's consumption rates and the inclusion of the surf zone microbial loop and the interstitial compartment to test for differences in structure and functioning of these coastal ecosystems. [Copyright &y& Elsevier]

Abstract: Understanding the relationships between beach morphodynamics and macrofauna assemblages has been critical in theoretical evolution of sandy beach ecology. However, macroscale studies that consider the concurrent effects of large-scale estuarine and morphodynamic gradients have been exceptional. The present study evaluates the combined effects of large-scale (>400km) salinity and morphodynamics on the distribution of Excirolana armata. Along a salinity gradient (from 0.10 to 34.30) generated by the Río de la Plata estuary (SW Atlantic Ocean), sixteen Uruguayan sandy beaches were analyzed over a two-year period. A conditional two-step procedure using a General Additive Model (2-step GAM) was performed in order to model occurrence (1st-step) and abundance (2nd-step) of E. armata, in relation to salinity, grain size, sand moisture, compaction and organic matter of the sand, slope, beach and swash width, and water and sediment temperature. The 1st-step GAM retained 6 physical descriptors in the model (decreasing order): mean grain size, organic matter, salinity, beach width, sand moisture and water temperature. The 2nd-step GAM showed that mean grain size, salinity, sand moisture, beach width, sand compaction and organic matter were the most important explanatory variables (in decreasing order) of abundance. Mean grain size was the main predictor in both models, suggesting an important substrate specificity of E. armata towards smallest grain sizes. A meta-analysis concerning large-scale variation in abundance of E. armata in sandy beaches of the Rio Grande ecoregion (28°S–35°S) of the Warm-Temperate Southwestern Atlantic Province gave compelling evidence of this high-substrate specificity of the E. armata. Salinity was also a key factor shaping patterns in occurrence and abundance, which increased from low to intermediate/high salinities (>20), reinforcing the notion of E. armata as a marine species with relatively high tolerance to estuarine conditions. The potential role that internal brooding gives for protection of offspring to osmotic stress is discussed. [Copyright &y& Elsevier]