Sandy beaches constitute a key ecosystem and provide socioeconomic goods and services, thereby playing an important role in the maintenance of human populations and in biodiversity conservation. Despite the ecological and social importance of these ecosytems, Brazilian sandy beaches are significantly impacted by human interference, chemical and organic pollution and tourism, as well as global climate change. These factors drive the need to better understand the environmental change and its consequences for biota. To promote the implementation of integrated studies to detect the effects of regional and global environmental change on beaches and on other benthic habitats of the Brazilian coast, Brazilian marine researchers have established The Coastal Benthic Habitats Monitoring Network (ReBentos). In order to provide input for sample planning by ReBentos, we have conducted an intensive review of the studies conducted on Brazilian beaches and summarized the current knowledge about this environment. In this paper, we present the results of this review and describe the physical, biological and socioeconomics features of Brazilian beaches. We have used these results, our personal experience and worldwide literature to identify research projects that should be prioritized in the assessment of regional and global change on Brazilian sandy beaches. We trust that this paper will provide insights for future studies and represent a significant step towards the conservation of Brazilian beaches and their biodiversity.

Climate change is predicted to lead to more extreme weather events, including changes to storm frequency, intensity and location. Yet the ecological responses to storms are incompletely understood for sandy shorelines, the globe’s longest land-ocean interface. Here we document how storms of different magnitude impacted the invertebrate assemblages on a tidal flat in Brazil. We specifically tested the relationships between wave energy and spatial heterogeneity, both for habitat properties (habitat heterogeneity) and fauna (β-diversity), predicting that larger storms redistribute sediments and hence lead to spatially less variable faunal assemblages. The sediment matrix tended to become less heterogeneous across the flat after high-energy wave events, whereas β-diversity increased after storms. This higher β-diversity was primarily driven by species losses. Significantly fewer species at a significantly lower density occurred within days to weeks after storms. Negative density and biomass responses to storm events were most prominent in crustaceans. Invertebrate assemblages appeared to recover within a short time (weeks to months) after storms, highlighting that most species typical of sedimentary shorelines are, to some degree, resilient to short-term changes in wave energy. Given that storm frequency and intensity are predicted to change in the coming decades, identifying properties that determine resilience and recovery of ecosystems constitute a research priority for sedimentary shorelines and beyond.

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The reproductive cycle and parasitism in the clam Anomalocardia brasiliana were studied in two different areas, an intermediate beach (Cidade) and a tidal flat (Araçá), in Southeast Brazil. Four gametogenic stages were described for males and females in both areas. Mature and spawning individuals were present throughout the period of study at Cidade and Araçá; however, major temporal differences were recorded between sites. Whereas only a few individuals in the resting stage were recorded at Cidade throughout the study period, resting stage individuals were frequent at Araçá. Moreover, a shorter period of gametogenesis was observed at Araçá than at Cidade. Oocyte number was the most effective parameter to differentiate gametogenic stages. An unidentified digenetic trematode was the only parasite infecting A. brasiliana at the study sites, and caused castration of all hosts. Parasite prevalence (proportion of infected hosts) was similar and low (ca 7.5%) at Cidade and Araçá and therefore is not expected to compromise the reproductive output of these populations. Comparison with data from previous studies suggests a latitudinal pattern for the reproductive biology of A. brasiliana, with resting stages occurring only at two high-latitude sites; however, no evidence was found for a latitudinal pattern of trematode prevalence in this species.

Evaluation of relative (allometric) growth provides useful information to understand the development of organisms, as well as to aid in the management of fishery-exploited species. Usually, relative growth analyses use classical models such as the linear equation or the power function (allometric equation). However, these methods do not consider discontinuities in growth and may mask important biological information. As an alternative to overcome poor results and misleading interpretations, recent studies have suggested the use of more complex models, such as non-linear regressions, in conjunction with a model selection approach. Here, we tested differences in the performance of diverse models (simple linear regression, power function, and polynomial models) to assess the relative growth of the trigonal clam Tivela mactroides, an important fishing resource along the South American coast. Regressions were employed to relate parameters of the shell (length (L), width (W), height (H) and weight (SW)) among each other and with soft parts of the organism (dry weight (DW) and ash-free dry weight (ASDW)). Then, model selection was performed using the information theory and multi-model inference approach. The power function was more suitable to describe the relationships involving shell parameters and soft parts weight parameters (i.e., L vs. SW, DW, and AFDW, and SW vs. DW). However, it failed in unveiling changes in the morphometric relationships between shell parameters (i.e., L vs. W and H; W vs. H) over time, which were better described by polynomial functions. Linear models, in turn, were not selected for any relationship. Overall, our results show that more complex models (in this study polynomial functions) can unveil changes in growth related to modifications in environmental features or physiology. Therefore, we suggest that classical and more complex models should be combined in future studies of allometric growth of molluscs.

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