Search Results (3)

Heavy metals enter river basins through industrial effluents, agricultural wastes, surface run-offs, and other human activities, negatively impacting aquatic and terrestrial life by bioaccumulating in the food chain. This problem is on a continuous rise in under-developed and developing countries, such as in Pakistan. Therefore, the current study was aimed to determine concentrations of heavy metals, essential trace elements, and macrominerals (Zn, Pb, Ni, Mn, Mg, Fe, Cu, Cr, Co, Cd, Ca, and As) in the water, sediments, and tissues (gills, liver, and muscles) of Bagarius bagarius and Bagre marinus in the Jhelum River, Pakistan. The hematological and biochemical profiles of these fish across two sampling sites (Jhelum Bridge Khushab, upstream, and Langarwala Pull—downstream) were also evaluated. Results showed greater bioaccumulation of heavy metals in fish downstream, correlating with higher concentrations of these metals in water and sediments downstream. In the case of B. marinus, the highest concentration observed was 16.59 mg/g (Ca), and the lowest concentration was 9.51 mg/g (Fe). In the case of B. bagarius, the highest concentration observed was 17.47 mg/g (Ca), and the lowest concentration was 7.95 mg/g (Mg). Increased activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were observed downstream. Hematological changes included increased white blood cells (WBCs) and decreased red blood cells (RBCs), lymphocytes, hemoglobin (Hb), platelets (Plt), and hematocrit (Hct). A significant correlation was observed among heavy metals across the water, sediment, and different tissues of B. marinus and B. bagarius. Moreover, principal component analysis (PCA) for both species along both sampling sites illustrated the relationship between fish tissues and metals. The current study concluded that the fish accumulated a significantly higher concentration of heavy metals downstream, which might be linked with dumping of the domestic wastes and industrial and agricultural runoff, adversely affecting both fish and human health. Full article

Bagarius bagarius (Hamilton, 1822) is widely distributed in South and Southeast Asian countries, including Bangladesh. This species is economically important as a game and food fish. The abundance of this fish is declining around the world, especially in Bangladesh, due to a variety of meteorological and mostly anthropogenic factors, which is potentially generating concern among the conservationists. Therefore, this species has already been declared a critically endangered species by IUCN Bangladesh. Although there is no specific conservation initiative for B. bagarius in Bangladesh, various measures are there to conserve fisheries resources, which may have an impact on conserving B. bagarius in this country. This study reviews the biology and ecology with its distribution throughout the country as well as the world, threats, conservation measures, and finds out the gaps in research on this fish. Moreover, this review suggests a suitable conservation framework to improve the conservation strategy for this critically endangered fish that can be replicated in other countries for the same purpose. Full article

Body size is one of the most important attributes of a species, but the basic question of why and how each species reaches a different “right size” is still largely unknown. Herein, three phylogenetically closely related catfishes from Sisoridae, including one extraordinarily large-sized Bagarius yarrelli and two average-sized Glyptothorax macromaculatus and Oreoglanis setiger, were comparatively studied using RNA-Seq. Approximately 17,000 protein-coding genes were annotated for each of the three fishes, and 9509 genes were identified as high-confidence orthologous gene pairs. Comparative expressions uncovered a similar functional cluster about ribosome biogenesis was enriched in different tissues of the upregulated genes of Bagarius yarrelli. Moreover, differentially expressed genes and positively selected genes revealed that the glycolysis/pyruvate metabolism and cell cycle pathways have also greatly enhanced in this large-sized species. In total, 20 size-related candidate genes (including two growth modulators: the serine/threonine-protein kinases 3 (AKT3) and adaptor protein 1 (SH2B1), and a crucial pyruvate kinase (PKM2A)) were identified by multiplying comparative analyses along with gene functional screening, which would play major roles in enabling the large body size associated with Bagarius yarrelli and provide new insights into body size evolution. In conjunction with field observations and morphological comparisons, we hypothesize that habitat preferences promote size divergence of sisorids. Full article