Induction of Micronuclei, Cellular Stress Response, and DNA Strand Breakage in Two Common Fish Species From Rivers and Reservoirs in Ilorin, Nigeria.

Indiscriminate discharge of home, agricultural, and industrial wastes into water bodies, most rivers and reservoirs around the world are becoming polluted. The ecotoxicological potential of this in fish species gathered from important reservoirs and rivers in Ilorin, Nigeria, was explored in this study. Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity), and Asa river (Unity) water samples were collected and physicochemical characteristics were investigated at five distinct sites: Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity), and Asa river (Unity) (Harmony). In Tilapia zillii and Clarias gariepinus, we measured serum biochemical (AST, ALT, ALP, serum ALB), histopathological (gills, lungs), and serum antioxidant enzyme responses (SOD, CAT, GPx, GR, GST) as a biomarker for oxidative stress, while micronucleus and comet assays were used to detect DNA damage. Except for DO, which was very low in the two rivers, the physicochemical parameters and heavy metals evaluated in the five separate water bodies were within the allowed levels of the NSDWQ and WHO standard for drinking water. In comparison to the Unilorin, Apodu, and Asa reservoirs, a slight increase in Pb was observed across the five sampling sites, which could contribute to increased biochemical and haematological profiles, histopathological lesions in the gill and lungs, inductions of MN, NA, and DNA single strand break in T. zillii and C. gariepinus collected from Asa rivers. This could be due to the indiscriminate dumping of effluents from adjacent industries, agricultural wastes, and household wastes into rivers.

Cellular stress response, induction of micronuclei and DNA strand breaks in two common fish species of Rivers and Reservoirs in Ilorin, North Central, Nigeria.

Most rivers and reservoirs in the world are prone to pollution because of indiscriminate disposal of domestic, agricultural and industrial wastes into the water bodies. In this study, we investigated the ecotoxicological potential this could pose in fish species collected from major reservoirs and rivers in Ilorin, north central, Nigeria. Water samples were collected and the physicochemical parameters were examined from five different sites; Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity) and Asa river (Harmony). We determined serum biochemical (AST, ALT, ALP, serum ALB), histopathological (gill, lungs), serum antioxidant enzyme responses (SOD, CAT, GPx, GR, GST) which serves as a biomarker for evaluating oxidative stress while micronucleus and comet assays were used to detect level of DNA damage in Tilapia zillii and Clarias gariepinus. The physicochemical parameters and heavy metal analysed (Pb, Mn, Cu, Ni, N, P, Fe, Cl, and Ca) in the five different water bodies were below the permissible limits of WHO and USEPA except the DO, which was very low in the two rivers, indicating hypoxia. Our results showed significant increase in biochemical and hematological profiles, histopathological lesions in the gill and lungs, inductions of MN, NA and DNA single strand break in Tilapia zillii and Clarias gariepinus collected from Asa rivers compared to the Unilorin, Apodun and Asa reservoirs. This may be attributed to indiscriminate discharge of effluents from nearby industries, agricultural and domestic wastes into the rivers.

CO2 and CH4 Emissions from an Arid Fluvial Network on the Chinese Loess Plateau

The emissions of greenhouse gases (GHGs) from inland waters are an important component of the global carbon (C) cycle. However, the current understanding of GHGs emissions from arid river systems remains largely unknown. To shed light on GHGs emissions from inland waters in arid regions, high-resolution carbon dioxide (CO2) and methane (CH4) emission measurements were carried out in the arid Kuye River Basin (KRB) on the Chinese Loess Plateau to examine their spatio-temporal variability. Our results show that all streams and rivers were net C sources, but some of the reservoirs in the KRB became carbon sinks at certain times. The CO2 flux (FCO2) recorded in the rivers (91.0 mmol m−2 d−1) was higher than that of the reservoirs (10.0 mmol m−2 d−1), while CH4 flux (FCH4) in rivers (0.35 mmol m−2 d−1) was lower than that of the reservoirs (0.78 mmol m−2 d−1). The best model developed from a number of environmental parameters was able to explain almost 40% of the variability in partial pressure of CO2 (pCO2) for rivers and reservoirs, respectively. For CH4 emissions, at least 70% of the flux occurred in the form of ebullition. The emissions of CH4 in summer were more than threefold higher than in spring and autumn, with water temperature being the key environmental variable affecting emission rates. Since the construction of reservoirs can alter the morphology of existing fluvial systems and consequently the characteristics of CO2 and CH4 emissions, we conclude that future sampling efforts conducted at the basin scale need to cover both rivers and reservoirs concurrently.

PARASITOCENOSES OF FISH IN RIVERS AND RESERVOIRS OF THE RYAZAN REGION

The wide distribution of trematodes and other helminths with a complex biological cycle in the reservoirs of the Ryazan Region indicates an increase in the level of their eutrophication. We performed a complete helminthological study of the ide (25 copies), roach (21 copies), and perch (29 copies) according to K.I. Skryabin. Taking into account complex hydrological indicators (species composition of higher plants, microphytes, fauna of hydrobionts and their parasites), the Pra River is a dystrophic water body, the Pronya River is an eutrophic water body, and the Novomichurinsk Reservoir is a hypertrophic water body. Parasites of Pra River were represented by nine species, the Pronya River by four species, and the Novomichurinsky Reservoir by six species. Trematodes dominate in all reservoirs of the Ryazan Region. We found an endemic focus of opisthorchiasis in the Pra River where the infection of the ide with metacercarias Opisthorchis felineus reaches 38–50% with an invasion intensity of up to 70 specimens. A number of species of trematodes (Ichthyocotylurus spp., Paracoenogonimus ovatus, Diplostomum spp., Posthodiplostomum spp., Tylodelphys clavata) and cestodes (Ligula intestinalis) should be considered as indicators for assessing an increase in concentration of dissolved biogenic substances in the water bodies. There is a direct correlation between the infection of fish with the above species of trematodes and cestodes (tapeworms) being indicators of the invasion intensity and the degree of eutrophication of the reservoirs.

Cyprinid Fishes: An Overview on the Present Status in Meghalaya, India

Cyprinid fishes of Meghalaya were investigated from twin drainage basins Brahmaputra and Barak-Surma-Meghna. 27 cyprinid fishes under 14 genus and 7 sub families were recorded from rivers and reservoirs of four different gradient zones. The diversity of Cyprinid fishes was highest with 49% representation of Cyprinids at lower elevation Zone IV below 500 m above MSL and bio diversity indices estimated as H: 3.05, 1-D: 0.10. In contrary lowest diversity with 7% representation of fishes was observed at elevation 1501 to 2000 m above MSL in Zone I with bio diversity indices H: 0.25, 1-D: 0.57. Distribution of commercially important cyprinids under genus Labeo, Systomus and Cirrhinus were found to be restricted to rivers of Barak-Surma-Meghna drainage basin. Catch percentage of cyprinids indicates that 70% of fishes exhibit occasional occurrence and 30% as common occurrence. High percentage of occasional occurrence, low catch composition percentage and with restricted distribution of commercially important fishes to only certain rivers of Barak-Surma-Meghna drainage is an indication of depletion of cyprinid resources in the state and requires taking multi prong conservation measures to protect cyprinid fishes in Meghalaya.

Campsurus truncatus Ulmer, 1920 (Polymitarcyidae): an Ephemeroptera in eutrophic waters

Aim The order Ephemeroptera, together with Trichoptera and Plecoptera, has been considered as sensitive in environmental quality assessment. However, the species Campsurus truncatus Ulmer 1920 (Polymitarcyidae) has been sampled in anthropically altered sites. In this paper, data on the occurrence of that species in the water quality monitoring network of the Environmental Agency of São Paulo State (CETESB) were gathered to review its position in the environmental gradient and in the quality assessment of rivers and reservoirs. Methods For this, a compilation of the occurrences and densities of Campsurus obtained in rivers and reservoirs of São Paulo state between 2001 and 2018, with grab samplers, was carried. Environmental factors, the Trophic State Index (TSI) and the Benthic Community Index (BCI) were related to the species densities to define its environmental requirements. Results The sublittoral zone of reservoirs was the most common habitat to C. truncatus, occurring more frequently at mesotrophic sites with fair ecological quality. Higher mean densities were recorded at eutrophic sites with good ecological quality conditions. The statistical analysis did not show linear correlation between C. truncatus densities and any of the analyzed environmental variable such as grain size, organic matter content, DO and light penetration, although there was a tendency for higher species densities occur in muddy, dark sediments and with intermediate levels of organic matter. As described in literature the presence of aquatic plants can actually benefit that population once the highest densities were observed in sites with many macrophytes, as Salto Grande reservoir, but it may be confusing the relationship between population density and environmental factors. Conclusions The high occurrence and densities of C. truncatus obtained in eutrophic environments suggest that the species should not be considered as a sensitive taxon in qualitative indexes, such as the BCI for rivers and the sublittoral region of reservoirs. Moreover, its exclusion from the richness of sensitive groups had low impact on the diagnoses already performed at the CETESB monitoring network.