Guanabara Bay, located at Rio de Janeiro, Brazil, is a highly urbanized and polluted estuary that houses different port areas, shipyards, and marinas of intense maritime traffic. This infrastructure is widely associated with the introduction and spread of non-native sessile species. A rapid assessment of non-native benthic sessile species conducted in the bay in late 2022 across 19 sites identified a total of 83 taxa, both native and non-native, classified into the following main groups: one Cyanophyta, 13 Macroalgae, 14 Porifera, 11 Cnidaria, six Bryozoa, five Annelida, 10 Mollusca, six Crustacea, 10 Echinodermata, and seven Ascidiacea. Our findings revealed the proliferation of the Asian green mussel (Perna viridis Linnaeus, 1758), a species noted for its exceptional ability to achieve extremely high biomass levels globally. In Brazil, the bivalve was first reported less than 6 years ago in 2018 at Guanabara Bay, on a mariculture farm at Arraial do Cabo (200 km away) in 2023 and more recently in the south (Paranaguá Bay), besides two coastal islands outside Guanabara Bay on natural rocky shores. The present survey recorded P. viridis at 17 sites, including natural substrata, co-occurring with native species. No Tubastraea spp. were observed in Guanabara Bay. Controlling and mitigating the consequences of bioinvasion events can be challenging, but biosafety protocols should be adopted in the near feature to minimize the risks and impacts caused by species dispersal.

Among the various forms of pollution, anthropogenic debris has been widely documented to cause entanglement and premature death of sea turtles, in addition to being ingested by these animals. One of the most affected species is the green turtle, which is commonly found along the south-central coast of Rio de Janeiro (RJ), an area characterized by high human population density. This study aimed to assess the impact of anthropogenic debris on green turtles by analyzing the gastrointestinal tracts of 66 individuals stranded along the south-central coast of RJ, as documented by the Santos Basin Beach Monitoring Project. Pieces of debris (1,683 in total) were found in 69.7% of the individuals analyzed, with the highest concentration observed in the large intestine. The most common types of debris were flexible plastic waste (50.5%; 850 items) and amber/brown debris (36.5%; 614 items) within the size range of 0.5 mm to 2.5 cm (41.2%; 693 items). No significant differences in debris composition were observed between turtles encountered inside and outside the bays. The substantial number

Several studies have reported on the presence of litter on beaches and in the oceans, but this represents the smallest part of the litter that ends up in the sea. Little is known about the litter that settles on the ocean floor, especially near coastal regions. Thus, this study quantified, classified and determined possible sources of subtidal benthic marine litter input off the coast of Rio de Janeiro, Brazil. Different sites were selected in Guanabara Bay, an area with the greatest industrial and population concentration in the state of Rio de Janeiro, and on the coasts of Costa do Sol and Costa Verde, where tourism represents the main economic activity. Material was collected by scuba diving at depths of between 5 and 15 meters at 31 sites distributed among the study areas. A total of 1, 209 items was found, with Guanabara Bay having the highest average concentration (92.40 items/km²), followed by Costa do Sol and Costa Verde (14.15 items/km² and 9.91 items/km², respectively). Plastic materials are the most representative solid waste (55.08%), followed by metals (14.97%) and fishing gear (12.48%). Results indicated that local activities affected the composition of the marine litter on Costa do Sol and Costa Verde, whereas in Guanabara Bay, anthropogenic material carried by rivers influenced the marine litter composition at certain locations in addition to local activities. Environmental education actions associated with tourism and fishing activities and better waste management are necessary to minimize the presence of litter in subtidal benthic environments.

Perna viridis is an invasive mussel species recently introduced to the southeastern coast of Brazil, where it coexists with the native Perna perna . Morphological similarity between these species, particularly in early life stages, has led to frequent misidentifications, compromising ecological assessments and management efforts. In this study, we applied geometric morphometrics to compare the shell shape of P . viridis and P . perna using 29 and 33 specimens, respectively, collected from Arraial do Cabo, Rio de Janeiro. Using Procrustes ANOVA, we detected significant shape differences ( F = 20.46, Z = 3.87, p < 0.01), particularly in the umbo, ligament curvature, posterior edge, and inferior margin. Perna viridis exhibited a more elongated and flattened profile, while P. perna displayed a robust, rounded shell. These findings demonstrate the potential of geometric morphometrics to support accurate species identification, essential for ecological monitoring, regulation of shellfish trade, and the development of conservation strategies targeting non‐indigenous species. As P. viridis continues to expand its range along the Brazilian coast, reliable morphological tools are critical for distinguishing it from native species and mitigating its ecological and economic impacts.