علوم محیطی (Mar 2024)
Quantitative and Qualitative Assessment of Microplastics Pollution in the Blackfin Barracuda (Sphyraena genie) in the Oman Sea
Abstract
Introduction: Due to the abundance and durability of plastic waste, especially in marineenvironments, it has caused significant environmental effects and has become one of the mostserious threats to oceans and biodiversity. Microplastics (1 micrometer to 5 mm), are animportant component of marine plastic pollution. The growing concern over the negative effectsof microplastics on human health has heightened attention to their presence in aquaticenvironments and edible aquatic animals. Therefore, the main goal of this research is toinvestigate the presence and quantitative (abundance and size) and qualitative (shape and color)microplastics in the digestive system of blackfin barracuda (Sphyraena genie) in the Oman Sea.Material and Methods: For this research, 27 pieces of S. genie with an average total length of42.5 ± 5.36 cm and total weight of 353.5 ± 2.5 grams were collected by local fishermen using gillnets from the northern shores of the Oman Sea were collected in the winter of 2020 and bioassayedafter being transferred to the laboratory. The extraction of microplastics was done by digesting thedigestive system with ten percent KOH and then vacuum filtration. Identification, counting anddetermining the characteristics of microplastics (shape, size and color) were done bystereomicroscope. Particle dimensions (μm) were measured using ImageJ software.Results and Discussion: According to the obtained results, 285 plastic particles were detected inthe S. genie on the coast of Oman. All the examined fish had microplastics in their digestivesystem. The average abundance of 10.5 ± 5.19 particles per individual and 0.8 ± 0.2 particles pergram of wet weight microplastics were observed in the digestive system of fish. The mostidentified microplastics were in the form of fiber (abundance: 73%), irregular fragments (26%)and film (1%). The identified microplastics were of various dark and light colors. The colorcombination according to abundance was black > gray > transparent > cream > red > blue anddark red > green and brown > pink and white > dark blue and peach. About half of themicroplastics were shorter than 300 μm in length, while only about 9% of the microplasticparticles were between 1 and 5 mm in length. In terms of size, microplastics were classified intoeight groups: category one (size: 1-100 micrometers; 64 microplastics), category two (100-300micrometers; 85 microplastics), category three (300-500 micrometers; 45 microplastics), categoryfour (1 mm-500 micrometers; 66 microplastics) category five (1-2 mm; 19 microplastic), categorysix (2-3 mm; 5 microplastic), category seven (3-4 mm; 1 microplastic) and category eight (4-5mm; without microplastics). The size of the fragments of microplastics was smaller than the fiber,and most of the fragments were less than 100 micrometers in size. Considering the small size ofmost microplastic particles and the presence of small fish remains (skulls, scales and gill fibers)and shell fragments in the digestive system of fish and the carnivorous diet of the S. genie, it canbe assumed that the source of the microplastic particles swallowed by these fish, which representenvironmental pollution with plastic waste is the secondary microplastics in this area.Conclusion: Microplastic particles were observed in the digestive tract of all the examinedsamples of S. genie. The isolated microplastics were in the form of fiber, irregular fragmentsand films. Black, gray, and transparent colors were evident as the dominant colors, and fiberwas the dominant shape in microplastics. Microplastics with a size of 1 mm and less were themost abundant (92%) size. The existence of microplastics in the investigated fish leads toecological and health concerns. Therefore, it is necessary to manage the entry of plasticpollutants into the marine environment.
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