Evaluation of the multiple biomarkers on identification of the vulnerable coastal pollution hotspots

Elemental Concentrations in the Shells of the Mussel Perna perna: Discrimination of Origin

The potential use of elemental concentrations and element:calcium (Ca) ratios as indicators of provenance for bivalve mollusks on the Brazilian coast is evaluated herein for the first time. The approach was applied to shells of the mussel Perna perna (target of extractive fisheries) from geographically close areas but under distinct environmental and anthropogenic influences. Both concentrations of the elements normalized by Ca and the total concentrations can be applied to discriminate the mussels' origin. However, the canonical approach using the total concentrations indicated variations regarding the discriminatory power, and the concentrations of the elements normalized by Ca were more robust in differentiating the provenance of the shells. The origin of mussels was better discriminated by six elementary ratios: Al:Ca, Fe:Ca, K:Ca, Mg:Ca, Mn:Ca and Na:Ca. Thus, monitoring studies aiming to discriminate the origin of P. perna individuals along their distribution based on these elementary ratios of the shell are recommended.

Toxicity assessment of lead, nickel and cadmium on zebra fish augmented with Bacillus xiamenensis VITMSJ3: An insight on the defense mechanism against oxidative stress due to heavy metals

Increase urbanization in recent years has let to discharge of heavy metals into the environment which has caused severe impacts on soil as well as water. Therefore the current study was aimed to assess the toxicity of lead (Pb), nickel (Ni), and cadmium (Cd) from the contaminated water using zebra fish Danio rerio and detoxification of metals upon augmentation with Bacillus xiamenensis. Exposure doses till 150 mg L^-1 of Pb, Ni and Cd in water showed lethal effects on fish. Similarly the histopathological analysis showed severe tissue disruption in the gills and liver which were less upon supplementation with bacterial strain VITMSJ3. On the 20th day, the uptake concentration of Pb, Ni and Cd in zebra fish was found to be 87 mg L^-1, 89 mg L^-1 and 91 mg L^-1 respectively with VITMSJ3, from the water. Antioxidant enzymatic activities showed an increase upon bacterial supplementation, which reduced the oxidative stress. Further SEM-EDAX analysis confirmed the presence of Pb, Ni and Cd ions adsorbed on the gills. The results clearly showed less oxidative damages in fish with increased head and reduced tail %. Overall, the results showed a significant difference (p < 0.05) among the treatments compared with the control.

Settleable atmospheric particulate matter harms a marine invertebrate: Integrating chemical and biological damage in a bivalve model

Some atmospheric pollutants may affect aquatic ecosystems after settling, generating contamination, bioaccumulation, and threats to aquatic species. Metallurgical processes result in the emission of settleable atmospheric particulate matter (SePM), including metals and metalloids, along with rare earth elements (REE) that are considered emerging contaminants. We report the 30-day exposure of brown mussels (Perna perna) to SePM collected in a metallurgical area of southeast Brazil close to estuarine ecosystems, followed by a 30-day clearance period, to evaluate the toxic potential of SePM to this model mollusk. The bioaccumulation of 28 elements identified in SePM and the sublethal effects were evaluated. REEs were found in SePM (Ce, Y, and La). Significant bioaccumulation of eight metals (Fe, Ni, Cu, Zn, Rb, Sr, Cd, and Ba) was found in the bivalves and correlates with the cytotoxicity and genotoxicity, showing a dose-dependent mode and suggesting a pre-pathological condition that could lead to ecological disturbances over time. Conversely, the unchanged lipid-peroxidation level after SePM exposure could indicate the effectiveness of the antioxidant system in protecting gills and digestive glands. The clearance period was not enough to successfully reverse the negative effects observed. So far, the current results enhance the comprehension of the negative role of SePM on metal bioaccumulation and metal-induced toxicity to aquatic biota. Thus, this report adds innovative findings on the role of SePM in aquatic pollution in coastal areas affected by atmospheric pollution, which should be relevant for future public policies to verify and control the environmental pollution.

Comparative Analysis of Root Na+ Relation under Salinity between Oryza sativa and Oryza coarctata

Na⁺ toxicity is one of the major physiological constraints imposed by salinity on plant performance. At the same time, Na⁺ uptake may be beneficial under some circumstances as an easily accessible inorganic ion that can be used for increasing solute concentrations and maintaining cell turgor. Two rice species, Oryza sativa (cultivated rice, salt-sensitive) and Oryza coarctata (wild rice, salt-tolerant), demonstrated different strategies in controlling Na⁺ uptake. Glasshouse experiments and gene expression analysis suggested that salt-treated wild rice quickly increased xylem Na⁺ loading for osmotic adjustment but maintained a non-toxic level of stable shoot Na⁺ concentration by increased activity of a high affinity K⁺ transporter HKT1;5 (essential for xylem Na⁺ unloading) and a Na⁺/H⁺ exchanger NHX (for sequestering Na⁺ and K⁺ into root vacuoles). Cultivated rice prevented Na⁺ uptake and transport to the shoot at the beginning of salt treatment but failed to maintain it in the long term. While electrophysiological assays revealed greater net Na⁺ uptake upon salt application in cultivated rice, O. sativa plants showed much stronger activation of the root plasma membrane Na⁺/H⁺ Salt Overly Sensitive 1 (SOS1) exchanger. Thus, it appears that wild rice limits passive Na⁺ entry into root cells while cultivated rice relies heavily on SOS1-mediating Na⁺ exclusion, with major penalties imposed by the existence of the "futile cycle" at the plasma membrane.

Effect of sublethal gradient concentrations of nickel on postlarvae of Penaeus monodon, Perna viridis and Terapon jarbua: Enzyme activities and histopathological changes

The present study evaluates the enzyme activities and histopathological changes in the post larvae (PL) of shrimp (Penaeus monodon), green mussel (Perna viridis) and fingerlings of crescent perch (Terapon jarbua) exposed to sublethal gradient concentrations of Nickel (Ni). The median lethal concentration (LC₅₀) values were 2.49, 66.03 and 43.92 mg Ni L^-1 derived for the PL of shrimp, green mussel and fish fingerlings respectively. No Observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values of the PL of shrimp were 46.5, 73.0 and 58.3 μg Ni L^-1 derived for the 21-d survival endpoint. The NOEC, LOEC and chronic values for the 30-d survival endpoint of the green mussels and fish fingerlings were 4.6, 6.32, 5.4 and 1.95, 2.6, 2.25 mg Ni L^-1 respectively. The isoforms of esterase, superoxide dismutase and malate dehydrogenase activities in the whole body tissues of test organisms were studied by native polyacrylamide gel electrophoresis after exposure to Ni. Histological examination of compound eye sections of shrimp revealed deformation, compression, fusion and detachement in the corneal cells from the corneal facet of the ommatidia indicating cellular anomalies due to Ni toxicity. Gill sections of the green mussel witnessed reduced haemolymph in sinuses of gill filaments, degenerative changes in interfilamentous junction and necrosis of frontal ciliated epithelial cells with vacuoles after exposure to Ni. Nickel affects the vision of shrimp and fish fingerlings, gills and byssus of green mussels.