Microplastic contamination in filter-feeding oyster Saccostrea cuccullata: Novel insights in a marine ecosystem.

Microplastic (MP) pollution has become a pressing global concern. Oysters are well-known filter feeders who ingest food by filtering microscopic particles suspended in the surrounding water. Along with organic matter, filter-feeding also causes accidental ingestion of MP by oysters. Hence, the aim of the current investigation is to understand the MP contamination in filter-feeding oysters. A total of 500 specimens of oyster Saccostrea cuccullata collected from the intertidal zone of five sampling locations on the Gujarat coast, India. Specimens underwent analysis following established protocols. Each specimen was found to exhibit MP contamination, showing an abundance of 2.72 ± 1.98 MPs/g. A negative relationship was found between shell length and MP abundance. Predominantly, fibers were documented across all study sites. Black, blue, and red-colored MPs with 1-2 mm sizes were most dominant. MP polymer composition was identified as polyethylene terephthalate and polypropylene. Findings provide baseline information on levels of MPs contamination, which can be used to monitor future effects of MP pollution.

On population structure and breeding biology of burrowing crab Dotilla blanfordi Alcock, 1900.

Background: The present study investigated the population structure and breeding biology of the burrowing brachyuran crab species Dotilla blanfordi Alcock, 1900, which is commonly found on the sandy beach of Bhavnagar, located on the Gulf of Kachchh, Gujarat coast, India. Methods: Monthly sampling was conducted from February 2021 to January 2022 at the time of low tide using three line transects perpendicular to the water line, intercepted by a quadrate (0.25 m2) each at three different levels of the middle intertidal region: 20 m, 70 m, and 120 m. The quadrate area was excavated up to 30 cm and sieved for specimen collection. The collected specimens were categorised into different sexes viz., male, non-ovigerous female, or ovigerous female. For the fecundity study of D. blanfordi, the carapace width (mm) as a measure of size as well as their wet weight (g), size, number, and mass of their eggs were also recorded. Results: The study revealed sexual dimorphism among the population, with females having significantly smaller sizes as compared to males. The overall population was skewed towards females, with a bimodal distribution of males and females. The occurrence of ovigerous females throughout the year suggests that the population breeds incessantly throughout the year, with the highest occurrence in August and September. A positive correlation was observed between the morphology of crabs (carapace width and wet body weight) and the size, number, and mass of eggs.

Population structure and fecundity of the Xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) on the rocky shore of Gujarat state, India.

Background: The population structure and breeding biology of the Xanthid crab, Leptodius exaratus (H. Milne Edwards, 1834), on the rocky intertidal region of Shivrajpur in Saurashtra coast, Gujarat state, were examined. Method: From March 2021 to February 2022, monthly sampling was conducted during low tide using catch per unit effort in the 500 m2 area. The sampled specimens were categorised into male, non-ovigerous female or ovigerous female. In order to estimate fecundity, the morphology of the crab specimens (carapace width and body weight) as well as the size of eggs, number of eggs and weight of egg mass were recorded. Results: A total of 1,215 individuals were sampled of which 558 individuals were males and 657 individuals were females. The size (carapace width) of males ranges from 5.15 to 29.98 mm, while females ranges from 5.26 to 28.63 mm which shows that the average size of male and female individuals did not differ significantly. The overall as well as monthly sex ratio was skewed towards males with a bimodal distribution while unimodal in females. The population breeds year-round, which was indicated by the occurrence of ovigerous females throughout the year. However, the maximum percentage occurrence of ovigerous females was observed from December to April which indicates the peak breeding season. The size of eggs, number of eggs and weight of egg mass were shown to positively correlate with the morphology of ovigerous females (carapace width and wet weight).

Microplastic prevalence in epipelagic layer: Evidence from epipelagic inhabiting prawns of north-west Arabian Sea.

The escalating global microplastic (MP) pollution severely threatens marine life due to insufficient waste management and widespread single-use plastic. This study focuses on assessing MP contamination in commercial prawns from Gujarat State, India. Ten prawn species collected at five main fishing harbors revealed 590 MP particles in their gastrointestinal tracts, averaging 6.08 ± 5.96 MPs/g and 1.15 ± 0.78 MPs/individual. Significant variations in contamination levels were observed between species and study sites. Pollution indices indicated very high contamination throughout the study sites. Threads were the predominant shape, with blue and black as prevalent colors. Size-wise, 1-2 mm MPs dominated. Polymer analysis identified polyethylene terephthalate, polyurethane, polystyrene, polypropylene, polyvinyl chloride, and acrylonitrile butadiene styrene. The findings provided crucial preliminary information for ecotoxicology and seafood safety investigations regarding MP contamination in commercially important prawns.

Quantitative assessment of microplastic contamination in muddy shores of Gulf of Khambhat, India.

Microplastics (MPs) have become a global concern due to their widespread distribution in marine ecosystems. The present study was aimed to assess MPs contamination in 21 muddy shores sites situated in the Gulf of Khambhat. From each site, five samples (1 kg each) were collected. In the laboratory, the replicates were homogenated, out of which a 100 g sample was used for analysis. The total number of MPs, shape, colour, size and polymer composition of MPs were assessed. The MPs abundance ranged from 0.32 ± 0.18 particles/g (Jampore) to 2.81 ± 0.50 particles/g (Uncha Kotda) among different study sites. Moreover, threads were recorded maximum followed by films, foams and fragments. In case of MPs colour, black and blue coloured MPs occurred dominantly, with sizes ranging from 1 mm to 5 mm. FTIR analysis identified seven different types of plastic polymers, out of which polypropylene was the dominant plastic polymer (32.46 %) followed by polyurethane (32.16 %), acrylonitrile butadiene styrene (14.93 %), polystyrene (9.62 %), polyethylene terephthalate (4.61 %), polyethylene (3.71 %) and polyvinyl chloride (2.51 %). Based on the results of the Contamination factor (CF) value, Alang, Mahua, Ghogha and Uncha Kotda were identified as very high contaminated sites (CF ≥ 6). Pollution Load Index (PLI) value of entire study area revealed the Gulf of Khambhat as a polluted area with MPs contamination (PLI > 1). While value of Hazardous Index (H) identified 12 study sites as class-V risk category (H value > 10,000). Moreover, Pollution Risk Index (PRI) value revealed fifteen sites as very high contaminated sites (PRI > 1200). Pollution indices can be useful in predicting the level of MPs contamination at the study site. Overall, the present study provides the information on MPs contamination in the coastal region of the Gulf of Khambhat that can be used as a baseline data for future studies on the ecotoxicity of MPs on marine biota.

Quantitative assessment of microplastic in sandy beaches of Gujarat state, India.

The present study was carried out to quantify microplastic prevalence among 20 sandy beaches on the Gujarat coast. Beaches were categorised into three different classes, viz. low-impacted sites, moderately impacted sites, and highly impacted sites based on anthropogenic pressure. Microplastic (MP) (≤ 5 mm) contamination on the beaches varied with an average of 1.4 MPs/kg to 26 MPs/kg sediment. Sutrapada site-1 and Porbandar showed the highest and lowest mean abundance of microplastics, respectively, among 20 selected beaches. Out of the total assessed microplastics, threads were the maximum (89.98%), followed by the films (4.75%), fragments (3.36%) and foam (1.89%). In terms of colour and size, different microplastics were recorded in this study. The chemical composition of microplastics was identified by ATR-FTIR as polypropylene (47.5%), polyethylene (26%), and polystyrene (25%). Tourism and fishing activities are the possible sources of higher microplastic contamination at highly impacted sites.