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The intermediate disturbance hypothesis (IDH) has been thoroughly investigated, but much controversy has been found for supporting its assumptions, which rely largely on the nature of the disturbance, spatial scale, and biological predictors tested. In this paper, richness of native and non-native species along a suite of Neotropical aquatic ecosystems across a broad latitudinal and geographical range was used to test the IDH predictions. An extensive literature survey was performed to compile native species richness and the occurrence of several taxonomic groups listed as non-native for twenty-four coastal rivers and bays evenly distributed into three climatic zones (tropical, transitional, and subtropical). The climatic gradient was confirmed by NMDS and PERMANOVA, but IDH predictions were only significantly supported for native and total species richness in the coastal bays. The distribution patterns of non-native marine species showed a linear instead unimodal pattern of increase with latitudinal climatic gradient, but the responses are complex and dependent of many non-exclusive factors, such as the sampling effort per ecosystem and the potential interference of other disturbance gradients that should be further addressed to unravel the role of IDH for non-native species distribution.

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.

The dark false mussel Mytilopsis leucophaeata occurs as non-native species in Asia, Europe and South America. Despite the low population density usually found in its native range, M. leucophaeata forms dense clusters in newly invaded areas which lead to impacts on local organisms and environment. Some of the impacts of non-native species on newly colonized areas may be positive. However, despite the empirical evidences of increase in water transparency by freshwater dresseinids, the hypothesis that dark false mussel enhances the quality of brackish water has never been tested so far. Thus, the present study aimed to determine M. leucophaeata impacts on the water quality of a nutrient-enriched coastal lagoon by (1) analyzing a historical water dataset for pre- and post-invasion at Rodrigo de Freitas Lagoon (Brazil) and (2) experimentally testing dark false mussel direct effects on water quality. Historical field data evidenced significant lower phytoplankton abundance and chlorophyll a, and higher water transparency for the post-invasion period. These pattens were also supported by time-series analyses, which detected a decreasing trend for total coliforms density and an increased trend for dissolved oxygen over time. Moreover, time series indicated a gradual increase in lagoon water level with time, but none or minor changes were evidenced for floodgates operation routine, meteorological variables, and the frequency of sewage input. In microcosms, M. leucophaeata was effective to increase water transparency and decrease E. coli densities. The combination of field and laboratory data partially supported the hypothesis that M. leucophaeata invasion promoted an improvement in lagoon water quality, but increased phosphorus availability through excretion in microcosm assays. Management of dark false mussel populations seems to be a potential strategy for water quality improvement within already invaded systems where high sewage-enriched effluents are released. However, as non-native species often unbalance ecological relationships and functioning of the invaded ecosystems, new introductions of M. leucophaeata must be avoided.

The mussel Perna perna is an intertidal bivalve that is widely distributed, cultivated and consumed in South Africa, Brazil and Venezuela. Among marine resources, bivalve mollusks are one of the most impacted by anthropogenic pollution, as they can accumulate pathogenic bacteria and water pollutants. Hemocytes are molluscan defense cells, and their abundance and functions can be affected in response to contaminants, such as bacterial load. However, no previous study has investigated the immune response of P. perna hemocytes. The aim of this study was to evaluate several immune parameters in P. perna as indicators of fecal pollution in mussel hemolymph and in seawater. We collected mussels and adjacent seawater from beaches with different levels of fecal contamination in Rio de Janeiro state (Brazil): Vermelha Beach (VB); Icarai Beach (IB); Urca Beach (UB); and Jurujuba Beach (JB). Hemocyte parameters (density, morphology, phagocytic activity and production of Reactive Oxygen Species - ROS) were evaluated using flow cytometry. We quantified Fecal Indicator Bacteria (FIB) in seawater by the multiple tubes technique for each beach and for hemolymph by the spread-plate technique. In agreement with historical evaluation of fecal contamination levels, UB presented the highest FIB abundance in seawater (thermotolerant coliforms, TEC = 1600 NMP 100 mL−1), whereas VB exhibited the lowest (TEC = 17 NMP 100 mL−1). UB mussels had six and eight times higher hemocyte density and phagocytic activity, respectively, than mussels from VB. Mussels from VB and IB presented a significantly lower number of total coliforms in hemolymph and a significantly higher relative internal complexity of hemocytes than those from UB and JB (p ≤ 0.01, PERMANOVA). ROS production by hemocytes was significantly lower in mussels from VB compared to those from JB (p = 0.04, ANOVA). Our results indicate a significant relationship between the level of fecal contamination in aquatic environments and the immune response of mussel hemocytes. Immune-related parameters may therefore be useful as indicators of bivalve health and environmental quality. Our flow cytometric analysis of P. perna hemocytes represents a new approach for studying Perna perna biology and might represent a novel tool for measuring organic pollution and water quality.

In the last decades, metal pollution has become one of the most critical environmental and public health concerns. Human use and processing of trace metals have altered these metals’ natural biogeochemical cycles, which is causing adverse impacts on human beings, natural communities, and aquatic ecosystems. In Brazil, mining and smelting are relevant metal contamination sources that affect many aquatic systems, besides agricultural residues, industrial and urban effluent discharges. In this context, seaweed biosorption is a promising technology for the removal of metals from wastewater that could prevent environmental contamination. Seaweeds show high metal sequestering capacities, cost-effectiveness, and eco-friendliness. In this review, we aimed to assess previous studies on trace metals biosorption using the brown seaweed of the genus Sargassum conducted in Brazil during the last two decades (1999–2019). An overview of metal pollution in Brazil and its possible treatments are presented. A theoretical basis regarding Sargassum and its mechanism of sorption of trace metals is described. We also discuss previous Brazilian studies on this topic, including their aims, the trace metals analyzed, and the experimental conditions that increase biosorption effectiveness, which include pH, temperature, algae pretreatment, and immobilization of the biosorbent in a matrix. Given the abundance of this genus throughout the Brazilian coast and its high metal recovering capacity, the algae sorption process remains an underexplored resource. We conclude this work with a patent search and a discussion of the future perspectives of Sargassum use by society.

The cell surface hydrophobicity of 60 isolates and three reference strains of Staphylococcus epidermidis was assayed by means of bacterial aggregation in liquid broth, phosphate-buffered saline, and in ammonium sulfate, as well as by affinity of the bacteria to n-hexadecane and polystyrene surfaces. In order to better characterize the isolates, the influence of bacterial growth time and enzyme treatment on cell hydrophobicity and the analysis of the slime production were also investigated. The strains presented the following profiles when assayed by the ammonium sulfate aggregation test (SAT): SAT1M, SAT 1M -2M, SAT 2M -4M, and SATor=4M. When SAT1M, the strains showed positive results for most of the cell surface hydrophobicity tests. None of the strains belonging to the groups with SATor= 1M showed spontaneous aggregation (SA), auto-aggregation (AA), or glass adherence, albeit 32 (62.7%) strains were polystyrene adherent and 42 (82.3%) presented weak adherence to n-hexadecane (20%). The best correlation of the results was found among the AA and glass adherence tests (100%), followed by SA/ glass adherence (98%) and SA/ AA test (98%). The polystyrene adherence test and microbial adherence to n-hexadecane test (MATH) showed 78% correlation. Proteinase K treatment reduced bacterial adherence to polystyrene, but did not influence the SAT values. Three distinct groups of strains were distinguished by the polystyrene micromethod and glass tube adherence assay: 0.0-0.4 O.D. group, including non-glass adherent isolates; 0.5-0.7 O.D. group, including strains with variable profiles (adherent or non-adherent); and 0.8-1.3 O.D. group, composed of glass-adherent strains. Evaluation by a single method seemed not to reliably determine the surface hydrophobicity characteristics of S. epidermidis clinical isolates. Auto-aggregation properties of the strains that adhered to glass seemed related to slime expression, rather than cell surface hydrophobicity. Data also suggested involvement of protein components in adherence to polystyrene, but not in auto-aggregation properties assayed by SAT.

Coagulase-negative Staphylococcus spp. (CNS) has been associated with primary bloodstream infections and implanted medical devices. Its importance is increasing due to the acquisition of resistance to oxacillin (Oxa) and, recently, resistance to mupirocin (Mup). Mupirocin, a topical antimicrobial, has been used in the prevention of staphylococci catheter colonization. Susceptibility to Oxa and Mup was analyzed by different testing methods in clinical CNS isolates. Among 112 CNS strains, 69 (61.6%) were Oxa R by the disk diffusion (DD) method and 72 (64.2%) grew on the oxacillin agar screen plate. S. epidermidis and S. haemolyticus presented high rates of oxacillin resistance, 75.4% and 96.1%, respectively. Twenty four (21.4%) strains were Mup R by the DD test and 21 of them (87.5%) were identified as S. epidermidis . The detection of the mecA and ileS-2 genes, determined by multiplex-PCR, showed that 72 (64.2%) CNS strains possessed the mecA gene, while 16 (14.3%) possessed the ileS-2 gene. Fifteen of these strains presented the two resistance genes simultaneously. The isolates containing the ileS-2 gene presented a minimum inhibitory concentration (MIC) >1024 μg/mL in the E-test, while low-level mupirocin resistance (MICs of 12–16 μg/mL) was observed in those strains without ileS-2. The resistances to high and low levels of mupirocin could not be distinguished when the DD test was used. The analysis of the Mup R S. epidermidis strains by Pulsed Field Gel Electrophoresis showed that 17 (80.9%) strains belonged to one of two patterns (A and B), which have been shown to be prevalent in hospitals in Rio de Janeiro. This report showed that the PCR method for detection of oxacillin and mupirocin resistance in CNS is necessary to determine accurate rates of these resistance, and will can help in the staphylococcal infections prevention and control policies in Brazil.