Biodiversity of commercially important finfish species caught by mid-water and bottom trawls from two different coasts of Arabian Sea: Threats and conservation strategies

Microplastics in water, sediments, and fish at Alpine River, originating from the Hindu Kush Mountain, Pakistan: implications for conservation

Microplastics (MP) pollution is an emerging threat to life and the environment. These particles are not restricted to human-inhabited lands but also found in different mountains and glaciers where the human population is relatively low. These MPs make their way to the river ecosystem from glaciers, rains, and municipal and industrial effluents. The current study was designed to highlight MPs' pollution in water, sediments, and fishes of the Swat River: originating from the Hindu Kush Mountain Range. These samples were collected from eight different sites across the river. An average concentration of MPs detected in water samples (305.79 ± 289.66 MPs/m³), fish (12.54 ± 8.02 MPs/individual), and sediments (588.29 ± 253.95 MPs/kg). The highest concentration was observed among water samples at Mingora city and the lowest at the confluence point of the rivers near Charsadda being 753.71 ± 330.08 MPs/m³ and 57.64 ± 31.98 MPs/m³, respectively. MP concentrations in the sediment samples were also the highest at Mingora city (834.0 ± 367.21 MPs/kg), and lowest at Chakdara (215.0 ± 20.0 MPs/kg). Among the fish samples, Schizothorax plagiostomus contained the highest while Wallago attu contained the lowest MP concentrations corresponding to 17.08 ± 8.27 MPs/individual and 5.0 ± 2.36 MPs/individual, respectively. Fibers were the most prevalent MPs in all the matrices representing 80%, 92%, and 85% of the total MP count in water, sediments, and fish samples. These findings highlighted that freshwater ecosystem are not free from MPs and are as much vulnerable to anthropogenic activities as marine ecosystem. Therefore, need attention not less than marine ecosystem awareness, education, ecotourism, sustainable reduction in plastic use, and strict rules and regulations could be helpful to prevent the anthropogenic menace.

Elemental composition of three-spot swimming crab Portunus sanguinolentus (Herbst, 1783) shell from the coasts of Sindh and Balochistan, Pakistan

The present study aimed to investigate the elemental composition of the hard shell of the three-spot swimming crab, Portunus sanguinolentus, collected from the coasts of Pakistan. Thirty crab shells were collected and divided into three groups considering their size. The element detection was performed by energy-dispersive X-ray spectroscopy with scanning electron microscope (SIM/EDAX). The mean concentration of carbon, oxygen, calcium, copper, magnesium, and phosphorus observed in the shell of P. sanguinolentus was 13.63 ± 6.21%, 46.25 ± 12.62%, 34.39 ± 18.33%, 3.19 ± 1.25%, 1.15 ± 0.99%, and 1.39 ± 0.51%, respectively. The concentration pattern of these observed elements in P. sanguinolentus shells was found in the following order: O > Ca > C > Cu > P > Mg. To compare among the three groups of shells, the highest concentration of calcium (54.60%) was obtained in large-sized shell groups, which was significantly different from the other groups (p < 0.05). A high concentration of copper was found to be accumulated in the large-sized (3.55%) and medium-sized (4.21%) shell groups, which was significantly higher than in small-sized shell groups (p < 0.05). In the case of the large-sized shell group, the mean concentrations of magnesium and phosphorus were significantly lower than the medium-sized shell group (p < 0.05). The results indicate that crab shells could act as a good bio-sorbent for several minerals in its ecosystem. P. sanguinolentus shell is very rich in calcium, magnesium, and phosphorus. Extraction of calcium, magnesium, and phosphorus from P. sanguinolentus shells could be profitable for biofertilizer and pharmaceutical industries.