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The crisis in small-scale fisheries (SSFs) is worsened by weak governance structures, requiring urgent transformation. Participatory arrangements like co-management offer potential to enhance resilience in these social-ecological systems. However, the performance of collaborative governance modes must be evaluated to support institutional learning, refine governance structures, and ensure the legitimacy of transformative changes. In Uruguay, Local Fishery Councils (LFCs) were institutionalized a decade ago to involve fishers in managing and governing SSFs. This study assesses the LFC for the yellow clam SSF using three approaches: analysis of LFC meeting minutes, compilation of stakeholder perceptions, and analysis of social networks. The study found a decline in session frequency due to limited resources caused by the termination of an externally funded project. Performance indicators from the minutes identified recurring concerns on assessment, governance, and management, and issues related to monitoring, control, and surveillance. The influence of markets and the impact of red tides on fisheries performance were also brought up. Stakeholders perceived successful management solutions achieved through collaborative efforts, supporting co-management and resource recovery progress. However, social network analysis revealed communication patterns marked by core-periphery structure, showing partial disconnection and reluctance of the coastal marine authority to engage in inter-institutional collaboration. Despite challenges from climate change and markets, the LFC played a crucial role in co-creating solutions, empowering fishers with new skills and knowledge. Findings stress the importance of collaborative governance in promoting sustainable management and supporting institutional learning for transformative change in SSFs. • Governance transformation into co-management is assessed in a small-scale fishery. • Mixed methods using content analysis of minutes and structured interviews. • Participatory management led to success, optimism, and support for co-management. • Challenges in sustaining governance infrastructure hinder effective management. • Social network analysis suggests that engaging peripheral actors enhances governance. [ABSTRACT FROM AUTHOR]

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

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]

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]

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]

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]

This paper analyses the spatial and temporal effects of a freshwater discharge (Canal Andreoni) on the macroinfauna community and its habitat in a sandy beach of Uruguay. Bimonthly, we examined 17 environmental variables plus macroinfauna abundance, biomass, richness, evenness and diversity of three sites: Andreoni, at the canal mouth, Coronilla, at 1 km, and Barra, at 13 km from the mouth. Both univariate and multivariate techniques showed an increasing degree of perturbation towards the canal. This was reflected by abiotic and biotic differences between sites and by a consistent two-dimensional ordination of the samples. A clear seasonal pattern was found, specially accentuated at Coronilla, where the effects of the canal were stronger in winter and weaker in summer. Multivariate linking between macroinfauna and its habitat highlighted the role of salinity as explanatory variable of the observed trends. [Copyright &y& Elsevier]

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]

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]

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]

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: This paper analyzes the spatial and temporal effects of a freshwater discharge (Andreoni Canal) on polychaete assemblages and the corresponding habitat in a sandy beach of Uruguay. Bimonthly, we examined 17 environmental variables plus polychaete abundance, richness, and diversity of three sites: ‘Andreoni’ (highly disturbed) at the canal mouth, ‘Coronilla’ (moderately disturbed), 1km far away, and ‘Barra del Chuy’ (less disturbed), 13km north from Andreoni Canal. The highly disturbed site showed significantly lower values of salinity, beach width, swash width, slope, chlorophyll a, and significantly higher values of sediment organic matter. Polychaete abundance and diversity significantly decreased towards the canal and were positively correlated with spatial variations in salinity, which was the most important factor structuring polychaete assemblages. The results highlighted the negative effects of this artificial freshwater discharge on the sandy beach environment and stress the usefulness of polychaetes as effective and reliable ecological indicators for these ecosystems. [Copyright &y& Elsevier]

Stable isotopes (δ 13 C and δ 15 N) together with chlorophyll a and densities of surf diatoms were used to analyze changes in trophic niches of species in two sandy beaches of Uruguay with contrasting morphodynamics (i.e. dissipative vs. reflective). Consumers and food sources were collected over four seasons, including sediment organic matter (SOM), suspended particulate organic matter (POM) and the surf zone diatom Asterionellopsis guyunusae . Circular statistics and a Bayesian isotope mixing model were used to quantify food web differences between beaches. Consumers changed their trophic niche between beaches in the same direction of the food web space towards higher reliance on surf diatoms in the dissipative beach. Mixing models indicated that A. guyunusae was the primary nutrition source for suspension feeders in the dissipative beach, explaining their change in dietary niche compared to the reflective beach where the proportional contribution of surf diatoms was low. The high C/N ratios in A. guyunusae indicated its high nutritional value and N content, and may help to explain the high assimilation by suspension feeders at the dissipative beach. Furthermore, density of A. guyunusae was higher in the dissipative than in the reflective beach, and cell density was positively correlated with chlorophyll a only in the dissipative beach. Therefore, surf diatoms are important drivers in the dynamics of sandy beach food webs, determining the trophic niche space and productivity. Our study provides valuable insights on shifting foraging behavior by beach fauna in response to changes in resource availability. [ABSTRACT FROM AUTHOR]

Abstract: Spatial heterogeneity is a conspicuous feature in life history traits of the deep sea red crab Chaceon notialis in the Southwestern Atlantic Ocean. However, a quantitative assessment of its spatial distribution in Uruguayan waters is lacking. A fishing survey was conducted in 2005 between latitudes 35°00′S and 37°00′S, water depth ranging from 300 to 1600m. A likelihood-based geostatistical approach showed a persistent spatial structure of the red crab for both the whole population and the harvestable stock, with global biomass estimates of 55,054t and 34,870t respectively. Similar estimates were provided by the “effective fishing area” technique (53,800t and 36,400t, respectively). C. notialis showed clear large-scale patterns: (1) concerning latitude, the highest density and CPUE were found between 35°40′S and 36°20′S. Males were mainly concentrated between 35°20′S and 36°00′S, whereas the relative representation of both ovigerous and non-ovigerous females increased at the northern end of the study area. Male individual weight increased asymptotically towards higher latitudes, while females followed the reverse pattern. (2) Bathymetric analysis showed the highest density and CPUE at depths close to 900–1100m, coinciding with the highest representation of males. By contrast, females mainly occurred in shallower waters (300–500m), and ovigerous females only between 300 and 400m. Individual weight of males and females consistently decreased from 300 to 1600m. Proportion of molting males increased with latitude and depth, whereas molting females followed the reverse trend. Spatially explicit management tools are suggested, including fishing closures between 300 and 500m depth and between latitudes 35°00′S and 35°40′S (main spawning area with the highest proportion of females) and at depths>1200m (recruitment area). [Copyright &y& Elsevier]

Abstract: The worldwide increasing trend in fishing catches together with the impact of fishing on ecosystems and inefficient fishery management have led to overfishing and frequent collapse of traditional fish stocks. In this context, the assessment of fishery-induced impacts and the implementation of ecosystem-based fisheries management programs are urgently required. In this study, the mean trophic level (TLm) and the fishing-in-balance (FIB)-index of Uruguayan landings during 1990 and 2001 were estimated using the trophic level of 60 fishery resources. A decline in total landings (Y) is observed, which is explained by the lower fishing yield in major fishery resources (especially demersal). Moreover, a marked decreasing trend in TLm at a rate of approximately 0.28 trophic levels per decade, and a decreasing trend in FIB-index since 1997 were observed. The present situation of fishery resources in Uruguay (fully exploited or overexploited) and the drop in Y, FIB and TLm can be considered as indirect indicators of the fishing impacts on the trophic structure of Uruguayan marine communities. We suggest that a more holistic ecosystem-based fisheries management could help to alleviate the critical situation of fish stocks in Uruguayan waters. [Copyright &y& Elsevier]