Evaluation of microplastic pollution and risk assessment in a tropical monsoonal estuary, with special emphasis on contamination in jellyfish.

Estuaries, which serve as vital links between land and coastal ecosystems, play a significant part in facilitating the transfer of plastic waste from the land to the ocean. In this research, we examined the prevalence, characteristics, and ecological risks of microplastics (MPs) in the extensively urbanized Cochin Estuarine System (CES), India. Additionally, it represents one of the initial evidence-based examinations of MPs ingestion by jellyfish in Indian waters, focusing on Acromitus flagellatus, Blackfordia virginica, and Pleurobrachia pileus species. The abundance of MPs found in the surface water of the Cochin Estuarine System (CES) varied between 14.44 ± 9 to 30 ± 15.94 MP/m3, with an average of 21.6 ± 11 MP/m3. In both surface waters and jellyfish from the Cochin Estuarine System (CES), fibers were the most prevalent type of MPs, with polyethylene (PE), polypropylene (PP), and polyamide (PA) being the most common polymer varieties. To evaluate the current levels of MPs and their effect on the CES, the Pollution Load Index (PLI), Potential Ecological Risk Index (PERI), and Polymeric Risk Index (H) were utilized. The high PLIestuary values (20.33), high Hestuary values (234.02), and extreme PERIestuary value (1646.06) indicate that the CES is facing an extreme ecological risk. Among the 280 jellyfish individuals examined, 118 (42.14%) were recognized to contain MPs with an average of 1.54 ± 2.68 MPs/individual. Pearson bivariate analysis revealed a significant correlation between the jellyfish bell size and number of plastics per individual. Comparison between jellyfish species revealed, the majority (66%) of the MPs identified in jellyfish were from A. flagellatus and 44 among the 50 jellyfish examined (88%) had MPs. These findings suggest that A. flagellatus may be a potential sink for MPs and may be utilized to be a bioindicator for monitoring MPs contamination in estuarine systems, aiding in future plastic pollution mitigation efforts.

Spatial distribution of total petroleum hydrocarbons in the seawater and sediment of Southeast coast of India.

The spatial distribution of total petroleum hydrocarbons (TPH) were analysed in the seawater and sediment samples collected from 27 locations along the Southeast coast of India. A first-time assessment was carried out on the distribution of TPH in both water and sediments for the entire coastline of Tamil Nadu. The concentration of TPH in seawater showed large spatial variation ranging from below detection level (BDL) to 47.5 µg/L and 0.01 to 53.12 µg/L in the surface and bottom waters, respectively. TPH levels exceeded the regulatory limits specified by FAO, China's Marine Monitoring Standards and the European Community in the seawater samples of Thoothukudi harbour (S2 station). The results showed that seawaters of southern stations were comparatively more polluted with TPH. TPH values in sediment were between 2.33 and 30.07 µg/g, and their levels remained below the Marine Sediment Quality Standard (500 µg/g). The spatial profile of TPH in sediments were contrasting to that observed for seawater. Higher TPH values were observed in sediments of the northern region than southern. TPH contents are strongly correlated with clay (R2 = 0.776; P < 0.001) and silt (R2 = 0.648; P < 0.001); conversely, there is a significant negative correlation between TPH and sand (R2 = 0.753; P < 0.001). ANOVA analysis demonstrated a significant difference (F = 11.75; p < 0.01) between the TPH concentrations of water and sediments. Non-metric multidimensional scaling (nMDS) was performed to determine the similarity among sampling stations that formed five crusted groups. Sediment along the southeast coast can be categorised as slightly polluted with respect to TPH as per the ATSDR standards.

In vivo appraisal of oxidative stress response, cell ultrastructural aberration and accumulation in Juvenile Scylla serrata exposed to uranium.

In vivo studies were performed to evaluate the organ specific tissue accumulation and cellular toxicity of uranium to mud crab Scylla serrata. The specimens were acclimated in natural seawater and the exposure to 50-250 µg/L uranium was investigated up to 60 days. The present study examined the effects of concentration and duration of uranium exposure in the tissue of S. serrata at cellular and subcellular level using scanning electron microscopy and bright field transmission electron microscopy in addition to histological analysis. The results indicated that accumulation of U in S. serrata was organ specific and followed the order gills > hepatopancreas > muscle. The response of key antioxidant enzyme activities such as SOD, GPx and CAT in different organs of crabs indicated oxidative stress due to U in the ambient medium and tissue. At 50 and 100 µg/L of U exposure, individuals were able to acclimate the oxidative stress and withstand the uranium exposure. This acclimation could not be sustained at higher concentrations (250 µg/L), affecting the production of CAT in the tissues. Cellular and subcellular changes were observed in the hemocytes with reduction in their number in consonance with the antioxidant enzymes. Histological aberrations like lamellar disruption of gill, necrosis of hepatopancreas, disruption and rupture of muscle bundles were observed at different concentrations and were severe at higher concentration (250 µg/L). Necrosis was observed in the electron micrographs of tissues shortly after 15 days of exposure. SEM micrograph clearly shows disrupted lamellae, folding of marginal canal and reduction of inter lamellar spaces in the gills of crab exposed to high concentration of uranium. Mitochondrial anomalies are reported for the first time in the present study in addition to the subcellular changes and vacuoles on exposure uranium in the cells of gill and hepatopancreas.

Comparative toxicity of chlorpyrifos: Sublethal effects on enzyme activities and histopathology of Mugil cephalus and Chanos chanos.

Ecotoxicological data and potential impact of chlorpyrifos (CPF) in the region are scarce for prescribing safety limits. Therefore, toxicity and sublethal impact of CPF on fish fingerlings of Mugil cephalus (3.0 ±â€¯1.2 cm) and Chanos chanos (3.0 ±â€¯1.5 cm) were studied. Acute and chronic toxicity tests were conducted by continuous flow through method and derived 96 h median lethal concentration (LC50). Mean LC50 value of 1.13 µg/L for M. cephalus, and 3.20 µg/L for C. chanos were derived by Probit. Chronic toxicity tests were conducted for 30 days and determined no observed effect concentration values of 0.09 µg/L 0.17 µg/L and lowest observed effect concentration values of 0.16 µg/L 0.32 µg/L and chronic values of 0.13 µg/L 0.25 µg/L for M. cephalus and C. chanos respectively. Key biomarker enzyme activities viz., EST, SOD and MDH were studied at sublethal concentrations of CPF. Native gel electrophoresis revealed gradual decrease in isoforms of EST and SOD activities, whereas MDH activity increased in fingerlings. These responses indicate inhibition of cholinesterase, antioxidants and synthesis of ATPs in the cells due to CPF stress. Pathological lesions were evaluated in gill and eye tissues of fingerlings. Epithelial fusion and degenerative changes were prominent in primary lamellae. Hyperplasia, lifting epithelium, fusion of lamellae and necrosis were evidenced in the secondary lamellae. Cellular anomalies in the retina of the eye of C. chanos include vacuoles in nerve fiber layer, shrinkage of outer plexiform layer and detachment of pigment epithelium layer. These changes indicate physiological disturbance in the gill and eye.

Biomarker and histopathological responses of Lates calcarifer on exposure to sub lethal concentrations of chlorpyrifos.

Bioassay tests on fingerlings (3.0 ± 0.5cm) of euryhyaline fish Lates calcarifer were conducted using customized continuous flow through system and derived 96h acute toxicity value for chlorpyrifos (CPF). Based on the measured concentration of CPF mean median lethal concentration (LC50) of 1.07µg/l with lower and upper 95% confidence limits (0.95 and 1.19µg/l). No observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values were found to be 0.4, 0.09 and 0.07µg/l respectively. Key biomarker enzyme activities such as esterase, superoxide dismutase and malate dehydrogenase were measured in whole body tissues of the fish fingerlings on exposure to sublethal toxicity of CPF resulting in inhibition of enzyme activities. Native gel electrophoresis revealed single isoform of SOD and MDH enzyme activities exhibiting time and concentration dependent inhibition. Interestingly, three isoforms of esterase activity were witnessed, two isoforms didn't show changes and one isoform was completely inhibited. The observed changes indicated continuous production of reactive oxygen species (ROS) in cells, affecting the integrity and function of cell membrane. Decreased MDH activity indicates reduction of ATP production in the mitochondria leading to susceptibility of fish fingerlings due to the imposed CPF toxicity. Histopathological changes are evident as physiological signatures of chemical interactions in the cell and are prominently used for the evaluation of toxic effects. Gills and eye tissues were selected considering the possible effects on respiratory surfaces and vision impairment. Their tissue sections were observed for changes in primary & secondary lamellae, and retina of the eye respectively. Prominent pathological lesions of gills and retina of the eye include degeneration of cells, fusion, lifting of epithelium and increased cellular space, detachment of pigment epithelium, fusion of photoreceptor cells, respectively on exposure to 30 days of sub lethal concentrations. CPF was found to be highly toxic, affecting the vital functions of respiration, vision and cellular activities leading to susceptibility of fish fingerlings.

Morphological changes induced by Caesalpinia bonducella seed extract on rat sperm: scanning electron microscope study.

Morphological changes in the sperm of albino rats observed under scanning electron microscope illustrate the disturbance in the plasma membrane, as well as in the acrosomal membrane upon treatment with graded doses of an alcoholic seed extract of Caesalpinia bonducella. Considerable changes in the shape and size of the sperm head were observed, with the middle region of the sperm head being slightly constricted dorsoventrally. Most sperm appeared morphologically abnormal in the head region showing the distortion at the anterior region and bulging of the acrosomal membrane when compared with the control. The results of this study suggest that such effects might have resulted from general disturbance in proteins and alteration in the cauda epididymal milieu, probably due to an androgen deficiency consequent to the treatment with Caesalpinia bonducella.

Hepatotoxic potential of Malathion in the freshwater teleost, Cirrhinus mrigala (Hamilton).

Freshwater edible fish, Cirrhinus mrigala, were exposed to a sublethal concentration (3 microl/L) of commercial grade malathion (50% EC) for 5, 15, or 25 days. After each exposure period, the liver was removed to study biochemical alterations. An increase in free amino acids, protease activity, and acetylcholine (Ach) levels, in contrast to decrement in total, structural, and soluble proteins, and acetylcholine esterase (AchE) activity were observed at 5 and 15 days of exposure, but on day 25 of exposure, all values reached near normalcy. The restoration to normalcy implies that after 15 d of exposure, an oscillatory phase in protein turnover toward a more-synthetic phase seems to occur, leading to the establishment of recuperation and adaptation phenomena.