Abstract The exploited mangrove crab Ucides cordatus, an important ecosystem engineer in South American mangroves, has a biphasic lifecycle with pelagic larvae developing offshore. Megalopae return to the mangrove forest to settle, i.e., metamorphose into benthic juveniles but its environmental drivers remain poorly understood. We postulate that conspecific crabs facilitate recruitment. In the field, we investigated whether the number of recruits is higher near conspecific burrows than in areas without conspecific bioturbation. Recruit sampling was conducted monthly from April 2008 to May 2009 along an environmental gradient. First, U. cordatus recruits of that year emerged from March to July. Intraspecific facilitation was indicated by significantly higher recruit numbers in bioturbated than in non-bioturbated substrates. Recruits were most abundant in zones with intermediate conditions of inundation, leaf litter standing stock, sediment consistency, luminosity, temperature, salinity, and pH. Avoidance of more inundated zones likely reduces predation by fishes and of less inundated zones helps individuals escape more stressful, drier environmental conditions. The observed habitat-specific recruitment pattern must be considered when designing field assessments of the population structure of U. cordatus (which should include sampling recruits) and enhancing stocks by releasing laboratory-cultivated larvae and first juveniles into the wild.

Abstract This study aimed to review previous records of Polydora species from Brazil, as well as provide new records, mainly from the Southeast and South regions of the country. In total, 11 species were distinguished and a key to their identification is given. Polydora cornuta , P. nuchalis , and a new species from the state of Rio de Janeiro, P. nonatoi sp. nov. were found to occur in silty sand tubes in soft sediments; six species were found to be opportunistic commensals boring in shells of various molluscs; P. colonia was found to only bore in sponges; and a new species, P. paulolanai sp. nov., was found to bore in both sponges and oyster shells in Paraná state. Adults of P. nonatoi sp. nov. have black stripes on the palps, black spots on the peristomium and 3−4 anterior chaetigers, short occipital antenna, falcate spines of chaetiger 5 with a large lateral tooth connected to main stem by thin sheath, and only capillary chaetae in the posterior notopodia. Adults of P. paulolanai sp. nov. have black bands on the palps, short occipital antenna, falcate spines of chaetiger 5 with transverse subdistal collar on concave side, and numerous needle-like spines loosely held in tufts in addition to capillary chaetae in the posterior notopodia. Polydora caeca Webster, 1879 is resurrected and treated here as a senior subjective synonym of P. neocaeca Williams & Radashevsky, 1999. Shell-boring worms from Brazil earlier identified as P. neocaeca or P. cf. haswelli Blake & Kudenov, 1978 are referred to P. caeca . The urgent need of molecular data for the correct identification of Polydora species from Brazilian waters is highlighted.

Abstract Of the 20,000 species of Annelida, most live in salt water, and the minority inhabits freshwater or terrestrial environments. Among the freshwater representatives, the family Aeolosomatidae draws attention mainly due to its enigmatic phylogenetic position. In the 1940s, Prof. Ernst Marcus was a pioneer in the study of Aeolosomatidae, mainly from collections in the state of São Paulo, Brazil. His research resulted in the description of eight species, four of which were new to science. Later, Marcus’ description of Aeolosoma headleyi was recognized as a fifth new species by Van der Land ( 1971 ) and named Aeolosoma marcusi in his honor. Recently, during a visit to the Museum of Zoology of the University of São Paulo (MZUSP), we found the original material deposited by Marcus ( 1944 ), but not formally registered. Thus, the aim of this work was to redescribe and designate the lectotypes and paralectotypes of Aeolosoma gertae Marcus, 1944 and Aeolosoma sawayai Marcus, 1944. We were able to study and photograph the specimens using a light microscope with Differential Interference Contrast (DIC). We were also able to identify and redescribe many important taxonomic features. However, some structures can only be observed in living individuals (as they are not preserved in the fixed material), which reinforces the need to study live specimens. This paper contributes to understand the diversity of Aeolosoma , provides new morphological knowledge and lays the foundation for new approaches to the study of aeolosomatids.

Abstract Coastal habitats are important feeding grounds for migratory shorebirds, which turns the coast of Piauí State into an important region for birds’ migration cycle. This study aimed to identify migratory shorebirds, analyze their patterns of habitat preference on coastal Piauí State, Brazil, and identify classes of invertebrates found in foraging sites. In total, 23,829 records of migratory shorebirds belonging to 15 species were found at feeding sites, presenting significant segregation between different foraging substrates (F1,23 = 8.41; p = 0.001). Limnodromus griseus (56.5±98.42; p > 0.001), Numenius hudsonicus (35.96±37.37; p > 0.001), and Calidris canutus (34.4±80.84; p < 0. 001) were the species accounting for the highest densities in muddy substrate. Calidris pusilla (77.37±178.02; p > 0.001), Charadrius semipalmatus (66±142.17: p > 0.001), and Calidris alba (56.5±181.24; p > 0.001) were the most significant species in sandy-muddy substrate. Birds’ lowest density was observed in sandy habitat, but C. alba (22.41±40.9) recorded the highest density in this substrate. Overall, most shorebirds (92.8 %) preferred foraging substrates presenting higher concentration of fine particles (silt, clay, and fine sand). Invertebrates belonging to classes Polychaeta, Gastropoda, Bivalvia, and Malacostraca prevailed in these sites. Therefore, substrate type and prey composition are factors influencing the density of migratory shorebirds in foraging sites. In addition, this region witnesses the occurrence of endangered species, and it reinforces the importance of these feeding sites for them during their migration to Brazil’s coastal region.

ABSTRACT Sandy shorelines show heightened susceptibility to alterations, highlighting the importance of reliable field measurements in forecasting coastal evolution. This study offers direct hydrodynamic measurements from the upper shoreface of a sandy beach in Paraná. We observed five distinct oceanographic conditions, including a high-energy event. Notably, wave height showed a positive correlation with northward longshore currents. During pre- and post-frontal periods, cross-shore flow predominates over longshore currents, particularly evident during low tides with pronounced offshore flow. These findings provide valuable insights for researchers seeking to quantify and model longshore sediment transport dynamics and morphological changes along sandy coastlines.

Abstract The introduction of species beyond their natural distribution area as a result of human activities is one of the main threats to marine biodiversity. In 2019, Perna viridis , an Indo-Pacific mytilid, was recorded for the first time in the coast of Brazil in Guanabara Bay (Rio de Janeiro State). In 2021, this species was recorded in the Northeast region of Brazil (Fortaleza, Ceará State). This record was subsequently replicated in studies from 2022, 2023, and 2024. The specimens from Ceará State were deposited in the malacological collection “Prof. Henry Ramos Matthews - Série B” of the Universidade Federal do Ceará. During a curation activity of this collection, these specimens were reanalyzed and their identification questioned. Therefore, this study aimed to confirm the record of P. viridis for the Northeast region of Brazil. According to the analyses, the individuals collected on the coast of Ceará are not P. viridis , but belong to Mytella strigata , a native species of the coast of South America. Thus, the occurrence of P. viridis in the Southwestern Atlantic remains restricted to the southeast region of Brazil.

Abstract Discarding unwanted catches is a significant issue arising from marine fishing activities, with far-reaching socioeconomic and ecological consequences. Uruguayan fishery regulations fail to penalize discarding but mandate self-reporting, providing an opportunity to analyze the discard from the two Uruguayan industrial bottom trawl fleets (shelf and coastal). By examining fishing logs, discard was estimated at 3,268 tons/year, accounting for 6.5% of the total catch (9.1% for the shelf fleet and 3.7% for the coastal fleet), with no discernible temporal trends for 2016, 2017, 2019, and 2020 nor significant seasonal variations in discard magnitude. Diversity, species richness, and evenness of the discard varied between fishing seasons and years. The most discarded species were Bassanago albescens in the shelf fleet and Brevoortia aurea in the coastal fleet. Both species showed magnitudes indicating a potential for exploitation development. Discard per unit of effort was mapped by fleet, enhancing the potential for discard information reconstruction for the area and thereby facilitating its inclusion in ecological and economic assessments. Discard reports have proven to be a valuable source of information that should be integrated into fisheries conservation and management initiatives.

Abstract In 2021, rubber bales appeared along the Brazilian coastline, causing environmental impacts. In this research paper, we identified a Second World War shipwreck that was associated with this event. Numerical simulations provided robust evidence to support the hypothesis that the origin of the 2021 bales was the MV Weserland . Moreover, it was sunk to a depth of approximately 5,000 m with a cargo containing rubber, tin, and wolframite. Tin is currently considered a strategic metal, with prices rising from USD 13,375/t in March 2020 to USD 34,462/t in May 2021. We provided evidence that the departure of rubber bales from the wreck and the increase in the price of its metal cargo were temporally associated; this reinforced the hypothesis of deep-sea unauthorized salvage in international waters (areas beyond national jurisdiction). The novel results demonstrate that historical shipwrecks are ticking time-bombs with risks of high and unmapped pollution in oceans worldwide.

Abstract During an expedition in January 2019, nanoplastics were sampled at a depth of −5,170 m over Cape Basin, in the South Atlantic Ocean. Using photo-induced force microscopy, it was suggested that these were polyethylene terephthalate (PET-like) particles with various sizes down to 100 nm, at different stages of degradation. By using a state-of-the-art Lagrangian 3D model, which includes fragmentation, we backtracked virtual particles to map the origin of the PET nanoplastics sampled at this location. Fragmentation processes are crucial to understanding the origin of nanoplastics (and microplastics) because they allow for detecting when and where particles become so small that they transition to a colloidal state, in which the buoyant force becomes negligible. We found that it is very unlikely that the nanoplastic particles entered the ocean as nanoplastics and then drifted to the sampling location. We also found that the fragmentation scheme, particularly the fragmentation timescale prescribed to the modeled particles, affects how they drift in the ocean by the velocity with which they sink. This study contributes to understanding the fate and sources of nanoplastics in the deep ocean and the development of 3D backtracking simulations for source attribution of ocean plastic.

Abstract Ecoacoustic indices may become an important tool to monitor marine ecosystems because they take passive and non-invasive measurements over wide spatial and temporal ranges. However, the performance and limitations of marine ecoacoustic indices are yet to be fully understood. This study evaluated the Acoustic Complexity Index (ACI), Acoustic Diversity Index (ADI), Bioacoustic Index (H), and Normalized Difference Sound Index (NDSI) in a marine protected area (MPA) named Resex mar Arraial do Cabo in a coastal upwelling in Rio de Janeiro, Brazil. All considered variables, such as water temperature, wind direction, solar radiation, and vessel traffic were monitored from September to December 2018. Principal component analysis showed that the ACI index was negatively correlated with the number of vessels, whereas the ADI and H indices were correlated with water temperature. After categorizing specific moments, the ACI configured the best index for differentiating specific times of day, whereas the ADI was ideal for distinguishing between moments with and without vessel presence. Thus, the ACI and ADI showed the best performance overall. This study identified the main variables influencing the soundscape of a productive upwelling region and intensely used MPA. Furthermore, this research has laid the foundation for further exploration and the development of a robust, non-invasive tool for monitoring marine environments.

Abstract A 117-year series of hourly-observed heights in the Río de la Plata estuary allows studying the recorded changes in positive storm surge (PSS) events spanning from 1905 to 2021, and calculate the annual mean river level (AMRL) trend. The analysis of PSS focuses on the trend of the annual number of events, the annual mean events duration, and the annual maximum PSS height. Seasonal analyses of these variables can also be conducted. This study aimed to ascertain any correlation between the rising AMRL and the evolution of PSS. Since AMRL increase is related to the effects of global warming, the observation series is divided into two periods based on the behavior of the curve of greenhouse gas emissions into the atmosphere. One period covers 1905 to 1962 and is characterized by a less pronounced curve slope, while the other period, 1965 to 2021, exhibits a drastically steeper curve slope. Moreover, two sets of data were obtained to calculate the PSS in two different scenarios for both periods: a hypothetical one, with no trend in AMRL, and a realistic one, maintaining the observed AMRL trend. The results show the acceleration trend of two of the analyzed variables, namely the annual number of events and the average duration of events, when transitioning from one period to the other (following the behavior observed in AMRL). However, the increase in AMRL could not be the only explanation of these accelerations. On the one hand, although the accelerations decrease when the hypothetical scenario is considered, they do not totally disappear. Moreover, the annual average duration of the events increases follows the realistic scenario when removing AMRL trend. On the other hand, the maximum height of PSS shows no trend in either period and remains unaffected comparing the two scenarios.

Abstract Guiana dolphins in the Costa Verde estuarine complex of southeastern Brazil are relatively well-studied, but there is still limited knowledge about their movement patterns between the two management units in the region. This study was based on the identification of the individual dolphins that transited between the two Costa Verde management units. Dolphins were photo-identified within the study area from 1994 to 2020, and two photo-identification catalogs were compiled based on this material. These catalogs were systematically compared on the finFindR software, which found 80 individuals that had transited between both management units, between 904 in Sepetiba bay and 808 in Ilha Grande Bay. The most common type of movement was a one-way (no return) movement from Sepetiba to Ilha Grande bay (62.5 %).

Abstract Human-wildlife conflicts pose significant challenges, requiring nuanced solutions rooted in ecological understanding and community engagement. In this sense, this opinion essay explores the first documented South American conflict scenario between Neotropic cormorants ( Nannopterum brasilianum ) and artisanal fisheries, located on Laguna Estuarine System, southern Brazil. Local reports converge on the information that, after 2015, Neotropic cormorants began to establish a reproductive colony on a non-breeders dormitory located at Noca Lagoon, near the estuary mouth. The colony’s consistent presence over the years and intense feeding activity, along with possible recruitment of cormorants, may lead to the perspective of increased population and nuances among fishermen. These concerns include vegetation suppression dealt by guano deposition, food competition, property damage, and fishery resources depletion. Despite no evidence of cormorant population increase and due the fact that fishing is an important regional activity, there was a response from local lawmakers to address this issue (Municipal Ordinary Law number 2.154/2020). The law imposes the harmful status to the native bird species and permit measures to “clean” harmful populations from properties. In addition, this law lacks control guidelines to cormorant populations, threating the local biodiversity and exacerbating the emerging human-wildlife conflict. To address these challenges, holistic and interdisciplinary approaches that understand cormorant behaviors and its interaction with fisheries activity are needed. From the knowledge bridge built from lawmakers, stakeholders, scientists, and fishermen, it is possible to foster dialogue and adopt a conceptual framework to mitigate conflict outputs and promote harmonious coexistence between wildlife and human activities.

Abstract The Fundão dam failure in the Rio Doce basin in 2015 triggered a significant socioecological regime shift. In this study, changes and strategies employed by small-scale fisheries (SSFs) in the wake of dam failure were analyzed. From 2021 to 2022, 441 semi-structured interviews were conducted with fishers in Espírito Santo municipalities, using the snowball method to sample 20% of total fishers. The interviews focused on socioeconomic aspects and post-disaster changes. Responses were statistically analyzed according to data type (chi-square test, ANOVA, or Kruskal–Wallis’s test). Overall, 96.35% of surveyed participants were impacted by the dam failure. The strategies adopted after the disaster characterized three groups: the first abandoned the fishery, the second made adaptations in their fisheries, and the third did not make any changes. In this context, we highlighted two aspects for study: (1) understanding the characteristics of the most affected groups and (2) understanding the main adaptations found. The first aspect mainly involved those farther from the coastal zone, including a higher proportion of women and older and more experienced individuals who currently have a lower mean income and greater economic dependence on monetary indemnities. The second aspect involved those who managed to make adaptations, largely aimed at maintaining fishing activities, often by changing the target species and/or fishing area. All groups identified environmental contamination as the main current challenge. This study contributes to the deepening of knowledge about local impacts and recovery strategies following human-made disasters. Moreover, understanding the experiences of groups affected to varying degrees, each with distinct implications and structural differences, can facilitate the development of collective strategies for more effective coping with the challenges faced by SSFs. This case presents potential for improvement by adopting more participatory frameworks aimed at implementing mitigation and recovery measures.