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• Biochemical markers related to mussel's oxidative status are efficient for metal's biomonitoring. • Genotoxicity and cytotoxicity assays provide a picture of hydrocarbon's contamination. • The neutral red assay gives a time-concentration cytotoxic response of a wide pollutants range. • P. perna hemocyte parameters are a useful approach for environmental pollutants biomonitoring. • Integrated biomarkers analysis can disclose a variety of pollutants in the environment. The brown mussel Perna perna (Linnaeus, 1758) is a valuable resource for aquaculture in tropical and subtropical coastal regions. It presents desirable characteristics for biomonitoring, including being sessile, widely distributed and abundant, and is a filter-feeder able to accumulate several classes of pollutants (e.g., metals, hydrocarbons, among others). Mussels' biological responses to pollution exposure can be measured as biomarkers, which include alterations ranging from molecular to physiological levels, to estimate the degree of environmental contamination and its effects on biota. This full review compiles two decades (2000–2020) of literature concerning biological effects on P. perna mussel caused by environmental pollutants (i.e., metals, hydrocarbons, and emerging pollutants), considering environmental and farm-based biomonitoring. Biochemical markers related to mussels' oxidative status were efficient for the biomonitoring of metals (i.e., antioxidant enzymes associated with oxidative damage in biomolecules). Genotoxicity and cytotoxicity indicators (i.e., comet, micronucleus, and neutral red assays) provided a depiction of hydrocarbon contamination. The neutral red assay gave a time-concentration cytotoxic response to a wide range of pollutants, including emerging pollutants (e.g., pharmaceuticals and biocides) and hydrocarbons. Perna perna hemocyte parameters provided a useful approach for biocide biomonitoring. This paper summarizes useful biomarkers from molecular to physiological levels in this mussel species used to identify and quantify the degree of coastal pollution. An integrated biomarker analysis may provide a way to overcome possible biomarker variations and assess multi-polluted sites. Nevertheless, it is necessary to investigate biomarker variations according to natural factors (e.g., season and gonad maturation stage) to standardize them for trustworthy biomonitoring. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Prorocentrum lima is a widely distributed marine benthic dinoflagellate that produces diarrhetic toxins, okadaic acid (OA) and its analogs, that may promote damage on bivalve tissues and cellular responses. Cultivation of the brown mussel Perna perna represents an important economic activity in the tropical and subtropical regions, where mussels may co-occur with P. lima. This study aimed to assess the behavioral, cellular immune responses, and pathological condition of P. perna following a short-term experimental exposure to P. lima. The toxic dinoflagellate treatment was compared to a non-toxic exposure to the chlorophyte Tetraselmis sp. at similar concentrations. The prevalence of pathological conditions and parasites were assessed, and a pathological index was applied by scoring the prevalences into four levels. Reaction time and the number of stimuli necessary for shell-valve closure response significantly increased after 72 h of P. lima exposure. Circulating hemocyte concentration was significantly lower in P. lima exposed mussels than in control mussels at 48- and 96 h of incubation, while hemocyte relative size in exposed mussels was significantly higher than that in control mussels. Comparatively, phagocytic activity and ROS production by hemocytes was significantly higher in mussels exposed to P. lima at 48- and 96 h of incubation, respectively. In addition, exposed mussels significantly presented exacerbated hemocytic infiltration in digestive organs, higher prevalence of moderate to severe atrophy in digestive tubules, and higher pathological index which suggests an impairment of mussel immunologic responses. A lower prevalence of Rickettsia-like organisms (RLOs), trematodes and copepods in P. lima exposed mussels suggests a direct toxic effect of OA on parasites. The exposure of mussels to P. lima is likely to occur frequently and may lead to constraints on mussel behavior, physiology, and pathological condition. Graphical abstract Image 1 Highlights • Lower reaction capacity and longer reaction time detected in P. lima exposed mussels. • Cellular immune parameters significantly shifted in response to P. lima exposure. • Higher hemocytic infiltration in digestive tissues of P. lima exposed mussels. • High incidence of moderate to severe pathological damages in P. lima exposed mussels. • Highest pathological index detected in mussels exposed to P. lima. [ABSTRACT FROM AUTHOR]

The brown mussel Perna perna is a valuable fishing resource, primarily in tropical and subtropical coastal regions. Because of their filter-feeding habits, mussels are directly exposed to bacteria in the water column. Escherichia coli (EC) and Salmonella enterica (SE) inhabit human guts and reach the marine environment through anthropogenic sources, such as sewage. Vibrio parahaemolyticus (VP) is indigenous to coastal ecosystems but can be harmful to shellfish. In this study, we aimed to assess the protein profile of the hepatopancreas of P. perna mussel challenged by introduced - E. coli and S. enterica - and indigenous marine bacteria - V. parahaemolyticus. Bacterial-challenge groups were compared with non-injected (NC) and injected control (IC) - that consisted in mussels not challenged and mussels injected with sterile PBS-NaCl, respectively. Through LC-MS/MS proteomic analysis, 3805 proteins were found in the hepatopancreas of P. perna. From the total, 597 were significantly different among conditions. Mussels injected with VP presented 343 proteins downregulated compared with all the other conditions, suggesting that VP suppresses their immune response. Particularly, 31 altered proteins - upregulated or downregulated - for one or more challenge groups (EC, SE, and VP) compared with controls (NC and IC) are discussed in detail in the paper. For the three tested bacteria, significantly different proteins were found to perform critical roles in immune response at all levels, namely: recognition and signal transduction; transcription; RNA processing; translation and protein processing; secretion; and humoral effectors. This is the first shotgun proteomic study in P. perna mussel, therefore providing an overview of the protein profile of the mussel hepatopancreas, focused on the immune response against bacteria. Hence, it is possible to understand the immune-bacteria relationship at molecular levels better. This knowledge can support the development of strategies and tools to be applied to coastal marine resource management and contribute to the sustainability of coastal systems. [Display omitted] • A total of 3805 proteins were found in the hepatopancreas of P. perna mussel. • Vibrio parahaemolyticus seems to be virulent and suppresses P. perna immune response. • E. coli and S. enterica triggered a general immune response against bacteria. • Proteins altered in response to all challenge-bacteria were vital for immune defense. • This study points out critical proteins against bacteria, promising for biotechnology. [ABSTRACT FROM AUTHOR]

Maricultural systems for food production have expanded worldwide since the 2000s, including the production of brown mussel Perna perna - a key aquaculture species in Venezuela, South Africa, and Brazil. Bivalves grown in sewage-polluted areas can act as sources for human diseases given their filter-feeding behavior. Moreover, sewage can affect mussels' microbiota and fitness, thereby making them more susceptible to infections and diseases, leading to mortalities. In the present study, we investigated the impacts of coastal fecal pollution on P. perna pathological conditions. Fecal indicator bacteria (FIB) were used to assess the microbiological quality in the seawater and mussels' hemolymph from four beaches located at Guanabara Bay, Rio de Janeiro, Brazil: Vermelha (VB), Icaraí (IB), and Urca (UB), where mussels are exploited for consumption and local market sale; and Jurujuba (JB) farming area where mussels are cultured. Additionally, mussels had their organs surveyed for pathological conditions and parasitic infection by histology. UB presented the highest FIB counts in seawater, followed by IB, JB and VB. Moreover, significantly lower values of total coliforms (TC) were found in mussels' hemolymph from VB and IB than JB and UB, which are probably related to differences in the hydrodynamic of these beaches; VB and IB are open beaches, while JB and UB are sheltered. Our findings suggest that mussel's hemolymph could be used as an indicator of the water quality. Mussels from VB and IB presented lower overall incidence of pathological conditions than ones from JB and UB, suggesting that higher fecal contamination increases mussel susceptibility to pathologies. Mussels from VB were associated with an elasmobranch parasite (Tylocephalum sp.) that indicate a conservative ecological dynamic. Our findings highlight that sewage inputs into coastal systems and farming areas raises the risks of parasitosis and diseases in mussels, which may compromise the quantity and quality of shellfish production and lead to economic losses. In response, public investments in urban planning and sanitary regulation close to coastal systems and farming areas are crucial to prevent future problems for the shellfish market and human safety, especially in developing countries such as Brazil. [Display omitted] • Total coliforms in mussel hemolymph corresponded to the beach's pollution degree. • Total coliforms in mussel hemolymph were correlated with pathological conditions. • Mussels from areas with higher fecal pollution were more susceptible to pathologies. • Parasites were detected in mussel populations from farming and harvesting areas. • Public sanitation is crucial to improve the quality and production of mussels. [ABSTRACT FROM AUTHOR]