Research Article
Biodiversity and Community Structure of Micro-Arthropods in the Memve’ele Dam, the Tributary River and the River Receiving the Evacuated Turbine Water (South-Cameroon)
Issue:
Volume 9, Issue 2, June 2024
Pages:
56-87
Received:
17 April 2024
Accepted:
29 April 2024
Published:
24 May 2024
Abstract: A survey was undertaken from July 2021 to January 2022 in South-Cameroon on the biodiversity of micro-arthopods in the Memve’ele dam (Site 1), the tributary river (Site 2) and the adjacent river (Sites 3 and 4). Four abiotic parameters were measured in-situ while nine other abiotic parameters were measured in the laboratory using standard methods. Micro-arthopods were counted and identified. Water quality was determined. BOD5, conductivity, NO2-, NO3-, pH, PO43-, temperature and suspended solids were on average within the standards for drinking water. Chlorophyll a, color, DO, NH4+ and turbidity values were on average above the standard upper limits. Based on the water quality index (WQI) raw waters were unfit for direct drinking (Dam: WQI=898.864; Site 2: WQI=752.451; Site 3: WQI=883.808; and Site 4: WQI=1,665.883) and presented ideal conditions for fish farming or irrigation for agriculture. A total of 5,487 specimens belonged to three classes, eight orders, 20 families, 57 genera, and 87 species and morphospecies (54 freshwater and 33 tolerant species able to develop in at least two water environments). Ectocyclops sp. was the most recorded species (10.6%), followed by Cyclops sp. (9.1%), Alona costata (8.9%), Mesocyclops sp. (7.9%), Tropocyclops sp. (7.5%), Senecella calanoides (6.8%), Diaphanosoma sarsi (6.1%), while other species were represented each by less than 5.0%. Low species richness, high species diversity and a very low dominance by a few species were noted. Assemblages were highly even (Pielou’s index close to 1). Species exhibited in all sites, a positive global net association. The assemblage recorded during the wet season at Site 3 functioned as a pioneer community (Broken-Stick model) while, the assemblage recorded during the dry season at Site 2 and the one recorded during the dry season at Site 3 functioned as nomocenosis (log-linear or log-normal models) and were therefore little evolved. In contrast, during the two seasons in the dam and Site 4, as well as during the rainy season in Site 2 and the combined seasons in Site 3, the assemblages functioned as highly evolved communities (Zipf or Zipf-models) with significant regenerative force, suggesting that these assemblages maintained a complex information network developed at spatio-temporal scales. The evolved state (close to natural balance) of the micro-arthopods communities should be preserved and protected.
Abstract: A survey was undertaken from July 2021 to January 2022 in South-Cameroon on the biodiversity of micro-arthopods in the Memve’ele dam (Site 1), the tributary river (Site 2) and the adjacent river (Sites 3 and 4). Four abiotic parameters were measured in-situ while nine other abiotic parameters were measured in the laboratory using standard methods. ...
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Review Article
Agricultural Pesticide-Induced Physiological Stresses in Freshwater Fishes of Bangladesh
Md. Mohibul Hasan*
,
Shayla Sultana Mely
Issue:
Volume 9, Issue 2, June 2024
Pages:
88-93
Received:
23 May 2024
Accepted:
19 June 2024
Published:
29 July 2024
Abstract: In Bangladesh, most croplands are situated in floodplains, enriched by numerous rivers and extensive freshwater wetlands. These areas also support productive open-water fisheries, crucial for supplying protein, generating income, creating jobs, and boosting the GDP. However, the widespread use of pesticides in these floodplains to protect crops and enhance food production leads to significant environmental issues. Agricultural pesticide residues enter water bodies through runoff, rainwater, drainage, seepage, and spray drift, contaminating natural water bodies and exerting continuous stress on aquatic life, including fish. Previous studies have detected pesticide residues in surface waters, sediments, and fish in Bangladesh, posing a major threat to wetland ecosystems. Research on freshwater fish species in Bangladesh has highlighted toxic effects on fish gonads, such as adhesion, inter-follicular space degeneration, ovigerous lamellae degeneration, necrosis, degenerated perinucleolar oocytes, cytoplasmic retraction in ovaries, and damage to sertoli cells. Additional observed effects include irregularly shaped seminiferous tubules, breakage of seminiferous tubules, and empty lumens in testes. Pesticides also inflict harm on other internal organs of fish, with gill effects like clubbing, reduction of gill filaments, telangiectasia of gill lamellae, hemorrhage, and damage to gill rakers. Kidney and liver damage include necrosis, cellular tissue degradation, acute cellular swelling, and irregular renal corpuscles, along with autolysis, vacuolation, and fatty changes in the liver. Developing embryos and larvae of freshwater fish are particularly vulnerable to the toxic effects of agro-pesticides. Studies reveal acute toxicity during early life stages, evidenced by deformities like edema, notochord deformity, caudal fin damage, yolk sac damage, posterior region damage, tissue fragmentation, black pigmentation on the yolk, body curvature, and lordosis in larvae. Exposed embryos exhibit deformities such as dark brown yolk sacs, notochord deformities, and broken eggshells. Mortality rates of fish embryos and larvae escalate with higher pesticide concentrations in water. Haemato-biochemical parameters serve as crucial indicators of pesticide exposure in fish studies, showing alterations in blood hemoglobin, glucose, RBC, WBC counts, and various erythrocytic abnormalities like twin cells, fusion, echinocyte formation, spindle-shaped, tear-drop, and elongated cells. Nuclear abnormalities include binucleated cells, nuclear buds, nuclear bridges, karyopyknosis, and notched nuclei. Research suggests that even at low concentrations, agro-pesticides disrupt physiological functions and life history traits of fish, adversely impacting the natural productivity and biodiversity of freshwater fish in Bangladesh.
Abstract: In Bangladesh, most croplands are situated in floodplains, enriched by numerous rivers and extensive freshwater wetlands. These areas also support productive open-water fisheries, crucial for supplying protein, generating income, creating jobs, and boosting the GDP. However, the widespread use of pesticides in these floodplains to protect crops and...
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