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Urban waste is a complex mixture of different substances, including microplastics and pharmaceuticals and personal care products. Microplastics have a high affinity for hydrophobic substances. One of these substances is triclosan, a bactericide used in a variety of hygiene products. Therefore, microplastics (MPs) may serve as a vector between triclosan and aquatic organisms. The current study sought to evaluate the effects of the interaction between microplastics and triclosan based on a mechanistic approach in which the oyster Crassostrea brasiliana was used as a model. The organisms were exposed to three conditions: the control, microplastic (MP), and microplastic contaminated with triclosan (MPT). The organisms were exposed for 3 or 7 days. After the exposure time, hemolymph was sampled for performing the neutral red retention time assay and, subsequently, the gills, digestive glands, and adductor muscles were dissected for measuring biomarkers responses (EROD, DBF, GST, GPx, GSH, lipid peroxidation, DNA strand breaks, and AChE). Our results demonstrate combined effects of MPs associated with triclosan on oyster physiology and biochemistry, as well as on lysosomal membrane stability. These results contribute to understanding the effects of contaminants of emerging concern and microplastics on aquatic organisms.

The Ostreidae are well known for their high intra-specific variation, which makes identification problematic. The present paper aims to provide a morpho-anatomical and taxonomic review of the Brazilian species of Crassostrea, as well as some congeneric species from other relevant areas. The Brazilian species are Crassostrea mangle sp.nov. and Crassostrea brasiliana. The exotic species Crassostrea gigas, cultivated in the southern region of the country, is also included in this study. Additional species are: Crassostrea virginica, from the Atlantic coast of the USA, the type species, and Crassostrea rhizophorae, a south-eastern Caribbean species that is supposed to occur in Brazil, but is here understood as a different entity endemic to that region. Taking into account their economic importance, the differentiation between these species is critical, and is essential for a better planning of production and preservation strategies. We point out the differences in almost all structures amongst these species, which are formally redescribed herein. The occurrence of the African species Crassostrea gasar in Brazil is established as false. The voucher specimens of previous studies responsible for this assumption were examined, evidencing a misidentification for Crassostrea brasiliana from an estuarine environment. The geographical distribution of the studied species is recognized as follows: Crassostrea rhizophorae in the south-east Caribbean Sea; Crassostrea mangle sp. nov. from Pará to the Santa Catarina, only in mangroves; Crassostrea brasiliana from Paraíba to Santa Catarina, both in rocky shores and mangroves; Crassostrea virginica ranges from the Atlantic coast of Canada to the Caribbean; and Crassostrea gigas originates from the Indo-Pacific, but has been introduced in southern Brazil. This paper also deals with conchological aspects of the endemic species Crassostrea praia, from south Lagoa dos Patos, Rio Grande do Sul; after a more detailed definition, and considering the deleterious effects of the nearby port and construction sites, it can be classified as an endangered species.

Aquatic organisms that inhabit coastal areas are often exposed to several contaminants. It is known that the bioaccumulation of contaminants can be amplified according to the species feeding habits and contaminant properties. As a consequence, species can experience different effects to contaminant exposure even if they inhabit the same area. The present study aimed to investigate the activities of carbonic anhydrase (CA), Ca2+-ATPase, and Mg2+-ATPase in different tissues (soft tissue, mantle, and gill) of three mollusk species (Lottia subrugosa, Stramonita brasiliensis, and Crassostrea brasiliana) with different feeding habits (herbivore, carnivore, and filter-feeder, respectively) which were sampled within a known contamination gradient at Santos Estuarine System (Southeastern Brazil). From the three enzymes tested, only CA was affected by the presence of contaminants within the contamination gradient evaluated. In general, the CA activity from the three species were lower in contaminated sites when compared to the reference site. The contrasting CA activity response observed in S. brasiliensis compared to L. subrugosa and C. brasiliana could be related to the tissue-specificity of this enzyme activity and species feeding habits (filter-feeders can accumulate more contaminants than herbivores and even carnivores). Results indicated that C. brasiliana mantle is the most suitable tissue for the use of CA analysis as a biomarker.

A bloom of D. acuminata complex was detected in early March 2008 in the shellfish farming area of Baía Sul, southern Brazil. Cell density reached up to 4.7 × 10⁴ cells/L at the surface by March 31st, quickly decreasing (<4.0 × 10³ cells/L) 1–2 weeks later as salinity increased (>32) in all sampling stations. On average, commercial-sized mussels, Perna perna, accumulated 11-fold higher okadaic acid (OA) levels in the digestive glands (DG) (maximum 2422 ng/g) compared to those of oysters, Crassostrea gigas (maximum 271 ng/g). Moreover, 50 % of the mussel DG extracts tested (n = 42) produced acute toxic effects as assessed by mouse bioassay, whereas all oyster samples produced negative results (n = 17). In parallel, juvenile oysters, Crassostrea brasiliana and C. gigas, and juvenile mussels, P. perna, exposed to a laboratory-simulated D. acuminata complex bloom (1350–13,750 cells/L) accumulated 7.5, 23.4, and 51.1 ng OA/g in whole bodies (22.7, 66.1, and 183.3 ng OA/g in visceral tissues), respectively. Toxin levels in the whole bodies dropped to similarly low average levels in all bivalve species (3.6, 3.7, and 1.3 ng/g, respectively) after 168 h of depuration. Mussels, therefore, detoxified OA at faster rates (0.023/h) than oysters C. gigas (0.010/h) and C. brasiliana (0.004/h).

Metal contamination is a threat to estuarine environments. They can accumulate in the food chain and cause toxic effects on aquatic organisms and human health. This study evaluated the concentrations of metals (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) in aquatic organisms of Antonina Bay (southern Brazil) to analyze whether the metal concentrations were in accordance with Brazilian food legislation and estimate the human risk of local seafood consumption. All analyzed organisms ( Centropomus parallelus , Mugil curema , Genidens genidens , Crassostrea brasiliana , and Xiphopenaeus kroyeri ) showed traces of metals in their tissues with different metal concentrations among species. Metal concentrations were generally higher in oyster C. brasiliana , and biomagnification was not observed. Cr and Zn concentrations were above the limits established by legislation for all species in at least one sample. The concentrations of the other metals were within permitted levels. However, concentrations of Cd, Cr, Fe, and Zn posed a human consumption risk. In general, the C. brasiliana oyster presented the highest risk for human consumption, probably due to its filtering habit. Thus, the results indicated that metal concentrations in the tissues of the Antonina Bay seafood can pose a risk to human health, and this chronic exposure to metals also can cause toxic effects on local aquatic biota.

This study focuses on the discussion of different lines of evidence (LoEs) applied to a sediment-quality assessment that considered the following: chemical concentrations of metals; polycyclic aromatic hydrocarbons (PAHs) in estuarine waters, sediments, and oysters (native and caged Crassostrea brasiliana ); PAHs in semipermeable membrane devices (SPMDs); simultaneously extracted metals-acid volatile sulfides (SEM-AVS); benthic community assessment (the exploratory benthic index and the relative benthic index); chronic toxicity tests with the sea urchin Lytechinus variegatus ; and bioaccumulation models. Significantly contaminated sediments from the Santos Estuarine System and the consequent toxicity of tested organisms were measured. Caged oysters presented bioaccumulation rates ≤2,500 % of total PAH content and 200 % of metal content when compared with control organisms from an uncontaminated area. SPMD results presented the same bioaccumulation pattern as caged oysters but at lower concentrations. Benthic communities presented some alterations, and there was a predominance of tolerant species in the inner part of the estuary. According to the SEM-AVS approach, metals should be assumed to be nonbioavailable, but experiments with transplanted C. brasiliana showed metal bioaccumulation, particularly in the cases of chromium, copper, mercury, and zinc. The weight-of-evidence approach was applied to compare and harmonize LoEs commonly used in sediment-quality assessments and to then classify estuary environments according to both their potential for having adverse effects on the biota and their possible ecological risks. All of the results of these approaches (except for SEM-AVS) were found to complement each other.

The Potiguar Basin has oil and gas production fields offshore and onshore. All treated produced water (PW) from these fields is discharged through submarine outfalls. Although polycyclic aromatic hydrocarbons (PAHs) are minor constituents of PW, their input into the marine ecosystem is environmentally critical due to potential ecological hazards. A 2-year monitoring program was conducted in the vicinity of the outfalls to evaluate PAH bioaccumulation in marine life from PW discharges. The study was performed using transplanted bivalves Crassostrea brasiliana and semipermeable membrane devices (SPMDs) to measure PAH concentrations via bioaccumulation and in seawater. The bioaccumulation of PAH in transplanted bivalves reached up to 1105 ng g −1 in the vicinity of the monitored outfall. Significantly lower PAH concentrations were found in the reference area in comparison to the studied area around the outfalls. Time-integrated PAH concentrations in seawater ranged from 38 to 0.3 ng L −1 near the outfalls and from 10 ng L −1 to not detected in the reference area. Both measurement techniques were found to be effective for determining a gradient of descending PAH concentrations from the outfalls. In addition, this study also evaluated the bioavailability of PAH for local marine biota and provided information about the influence of PW discharges on the water quality of marine ecosystems.

Coastal ecosystems of northeastern Brazil have important biodiversity with regard to marine mollusks, which are insufficiently studied. Here we provide an inventory of mollusks from two sites in the estuary of the Paraíba River. Mollusks were collected in 2014 and 2016 on the coast and sandbanks located on the properties of Treze de Maio and Costinha de Santo Antônio. The malacofaunal survey identified 12 families, 20 genera and 21 species of bivalves, 17 families, 19 genera and 20 species of gastropods and one species of cephalopod. Bivalves of the family Veneridae Rafinesque, 1815 were the most representative, with a total of five species. Gastropods of the family Littorinidae Children, 1834 had the greatest species richness. The most abundant species were: Neritina virginea (Linnaeus, 1758), Brachidontes exustus (Linnaeus, 1758), Crassostrea brasiliana (Lamarck, 1819), Cerithium atratum (Born, 1778), Anomalocardia brasiliana (Gmelin, 1791), Parvanachis obesa (C. B. Adams, 1845), Phrontis polygonata (Lamarck, 1822), Littoraria angulifera (Lamarck, 1822), L. flava (King, 1832), Tagelus plebeius (Lightfoot, 1786), Echinolittorina lineolata (d'Orbigny, 1840) and Iphigenia brasiliensis (Lamarck, 1818). The results show that the study area has considerable species richness of Mollusca, requiring environmental monitoring in the region mainly due to the economic importance of some species to the local population.

This study aimed to determine the effect of temperature and period of postharvest storage on the microbiological quality and shelf life of raw mangrove oysters, Crassostrea brasiliana. A total of 150 dozen oysters were collected directly from the points of extraction or cultivation in southern Brazil, and in the laboratory, they were stored raw at 5, 10, 15, 20, and 25°C for 1, 4, 8, 11, and 15 days. On each of these days, the oysters were subjected to microbiological analyses of aerobic mesophilic count, total coliforms, enterococci, Escherichia coli, Staphylococcus aureus, and Salmonella. None of the tested samples under any storage condition showed contamination levels above those allowed by Brazilian legislation for E. coli, S. aureus, and Salmonella, and there was no change (P > 0.05) in the counts of these microorganisms due to the temperature and/or period of oyster storage. Counts of enterococci and total coliforms showed a tendency to increase (P < 0.05) among the different temperatures tested. Raw mangrove oysters remain in safe microbiological conditions for consumption up to 8 days after harvesting, regardless of temperature, and their shelf life may be extended to 15 days if they are stored at temperatures not exceeding 15°C.

Three species of mangrove oysters, Crassostrea rhizophorae, C. brasiliana, and C. gasar, have been described along the Atlantic shores of South America and Africa. Because the distribution of these molluscs is of great biological and commercial interest, their taxonomy and distribution deserve further clarification. Therefore, 15 populations were sampled from both continents. Their 16S mitochondrial polymorphism was studied by sequencing and PCR-RFLP analysis. Two haplotypes were identified. Haplotype a was the only one observed in Africa, but it was also observed in South America together with haplotype b. Because C. gasar is the only mangrove oyster identified on the west coast of Africa, haplotype a was attributed to this species, which has thus been shown to occur in South America. Haplotype b is attributed to C. rhizophorae. The karyotypes of specimens of C. gasar, from Africa and from South America, were very similar, and both species were observed at the same location in Brazil. The occurrence of C. gasar in South America adds a third species-in addition to C. rhizophorae and C. brasiliana-to the list of species present along these coasts. The predominant surface circulation patterns in this part of the Atlantic Ocean favor the hypothesis that C. gasar was transported from Africa to America. Finally, a phylogenetic tree built with seven 16S sequences from Crassostrea and Saccostrea species showed that C. gasar is intermediate between the American Crassostrea species (C. virginica and C. rhizophorae) and the Asian species (C. gigas and C. ariakensis).