Seasonal distribution and abundance of microplastics in the coastal sediments of north eastern Arabian Sea.

The present study reports site-specific data on the seasonal variation in microplastic abundance and characteristics in coastal sediments along the North Eastern Arabian Sea, India. The abundance of MP in coastal sediments ranged from 4400 to 15,300 items/kg dry weight (DW), with the dominance of the size ranging between 100 and 500 µm. In the studied sediment samples, fibers were the most dominant form, followed by fragments. Ten different microplastics polymers were recorded during the study with dominance of polyethylene, polyester, polyamide and all the recorded plastic items in the sediments were denser than water, except polyethylene. The mean abundance of MP in sediments was significantly higher in the monsoon season. During this season, freshwater flow increases to the sea, which brings a higher concentration of microplastics from catchment areas. For a better insight, more time-series data and research are required to assess the source of MP pollution, understand spatial-temporal variations in MP abundance and their possible hazardous impacts on marine organisms and the environment.

Effect of temperature on growth performance and immuno-biochemical changes in endangered golden mahseer, Tor putitora (Hamilton, 1923).

The present study to evaluated the effect of different thermal regimes on growth performance, oxidative stress, antioxidant enzymes, and immuno-biochemical responses of endangered golden mahseer, Tor putitora. A total of 144 healthy fingerlings were randomly distributed into four experimental groups (13 °C, 16 °C, 19 °C, 22 ± 0.5 °C) in triplicate rectangular fiberglass reinforced plastics tanks. The highest and lowest Growth rate, Specific growth rate, Daily growth index, Thermal growth coefficient, Viscera-somatic index, and Growth hormone were observed at 19 °C and 13 °C, respectively. The lowest SGR and VSI were observed at 22 °C. The feed conversion ratio was significantly higher in the control group (p < 0.05), whereas there was a significant decrease in all the treatment groups. The highest and lowest hepato-somatic index was observed at a temperature of 13 °C and 16 °C, respectively, while no significant (p > 0.05) impact of temperature regimes were observed on the length-weight relationship. Regarding hematological indices results, the hematocrit, hemoglobin, total erythrocyte count, and total leucocyte count were significantly higher at 13 °C, whereas the lowest was observed in all the treatment groups (p < 0.05). Higher myeloperoxidase activity and lysozyme activity were observed at 13 °C, whereas lowest at 22 °C. Anti-oxidant potential, SOD, and catalase (muscle) were significantly higher in the control group, whereas they gradually decreased with an increasing temperature. Catalase (liver) level was significantly higher at 22 °C. GST content was significantly higher at 22 °C compared to 13 °C, and GST content increased gradually with an increased temperature. The lipid peroxidation level in the liver and muscle was significantly higher at 22 °C and 13 °C, respectively. The present study concluded that the different phenotypic, antioxidative, and immuno-biochemical modulations of golden mahseer fingerlings in response to different temperature regimes could be used for better management and propagation.

Abundance and characteristics of microplastics in gastrointestinal tracts and gills of croaker fish (Johnius dussumieri) from off Mumbai coastal waters of India.

The present study was conducted to establish the intensity of microplastic pollution in demersal fish species, Johnius dussumieri, from the north eastern coastal waters of the Arabian sea. MP recovered were analysed for size, morphology, colour, and polymer type. The study results indicated that the GI tract and gills of individual fishes had 6.6 ± 1.7 and 6.2 ± 1.7 items, respectively. The microplastics having a size of <100 µm consisting of beads were found to be most predominant. Black and blue were the most present colours of microplastic in the tissues. Among the different studied months, a higher number of MP incidence was observed in the post monsoon period. There is no significant correlation observed between the microplastic numbers in gills and guts tissue. The present study shows that there is a potential risk of microplastic bioaccumulation in the fish body and subsequent risk to the consumers and organisms sharing the food chain.

Microplastic pollution in coastal ecosystem off Mumbai coast, India.

Microplastics (MPs) are anthropogenic pollutants which can adsorb toxic substances from surrounding water and absorb into the fish body. During the present study, MPs were observed in water, sediment, and gastrointestinal tracts of marine biota samples collected from the coastal waters of Mumbai, India. The mean abundances of MPs recorded in water samples 372 ± 143 items/liter and 9630 ± 2947 items/kg dry weight (DW) in sediment samples. The mean abundance of MPs in pelagic fish species varied from 6.74 ± 2.74 to 9.12 ± 3.57 items/individual and in the demersal species the values ranged from 5.62 ± 2.27 to 6.6 ± 2.98 items/individual. Shape-wise, four type of MPs were observed in the surface waters, sediments and all studied species, predominantly fibers, followed by fragments, pellets/beads, and films. Seven different colors of MPs (red, blue, black, translucent, brown, green, and yellow) were observed from studied samples. MPs of size below 250 µm formed the dominant size in the surface water, sediments, and biota samples except Bombay duck and Malabar sole fish. Based on Raman spectroscopy analysis, eleven types of plastic polymers identified from all studied samples. Thus, presence of MPs in studied biota indicates the transfer of MPs through interlinked food chain/web to higher trophic levels and the occurrence of MPs in the fish gut underlines the necessity of more studies on processing interventions for reducing the microplastic contamination in fish for human consumption.

Incidence of microplastics in gastrointestinal tract of golden anchovy (Coilia dussumieri) from north east coast of Arabian Sea: The ecological perspective.

Anthropogenic marine litters or microplastics (MPs) accumulation in marine organisms is an emerging environmental threat. In this background, the gastrointestinal tract of Coilia dussumieri (n = 150) was studied in the samples collected from the fishing grounds of the north east coast of Arabian Sea through experimental fishing. Out of the total 150 specimens collected, all showed the incidence of microplastic particulates in the guts. The average abundance of MPs was found to be 6.98 ± 2.73 items/individual whereas gastrointestinal tract recorded with an average number of 28.84 ± 10.13 MPs/g in the gut material. The dominant MPs were found in the size range of 100-250 µm and of fibers type mostly blue in color. The prevalence of MPs in Coilia dussumieri is a matter of serious concern due to its ecological consequences due to trophic transfer in the connected food chains and probable threats to the health of human beings consuming the fish.

Microplastics in shrimps: a study from the trawling grounds of north eastern part of Arabian Sea.

Accumulation of microplastics (MPs) in marine organisms poses an imminent environmental threat and health risk due to the possibility of trophic transfer of accumulated MPs in ecologically important food chains. In this context, a field-level study was conducted on the fishing grounds of the north eastern part of the Arabian Sea through experimental fishing, and the gastrointestinal tracts (GT) of three different species of shrimps (n=180) were examined for the incidence of microplastics. The results showed that all shrimp caught from the fishing grounds had significant levels of MPs in the gastrointestinal tracts. A total number of 1220 microplastic items were recorded from the pooled samples, with an average of 6.78 ± 2.80 items per individual. The gastrointestinal tract showed an average number of 70.32 ± 34.67 MPs per gram of the gut material. The MPs with the size range of 100-250 µm were the most abundant form found in the shrimp species analyzed. Among the colored MP particles, black color was the most dominant (30.16%) form of MP. Fibers, fragments, pellets, beads, and films were the common morphotypes; however, fibers showed an occurrence of 39.40%, 47.39%, and 41.89% in the GTs of Metapenaeus monoceros, Parapeneopsis stylifera, and Penaeus indicus, respectively. In the present study, six types of plastic polymers were identified from the GTs of the studied samples. The findings confirm the presence of microplastics in the natural habitats of shrimps beyond the coast and indicate that shrimps caught from these coastal fishing grounds contain MPs in their gut. The findings underline the immediate scientific intervention for the microplastic reduction in the marine environment.