Wael A. Omar

Risk Assessment and Toxic Effects of Metal Pollution in Two Cultured and Wild Fish Species from Highly Degraded Aquatic Habitats

Lake Qaroun is an inland lake at the lowest part of El-Fayoum depression, Egypt. It receives agricultural and domestic non-treated drainage waters, which are also used for aquaculture in Qaroun area. The results of the present study aimed to provide comparable data between wild (collected from Lake Qaroun) and cultured (collected from Qaroun fish farms and the reference site) Nile tilapia Oreochromis niloticus and mullet Mugil cephalus, as indicators of natural and anthropogenic impacts on aquatic ecosystem as well as to evaluate the human hazard index associated with fish consumption. Metal concentrations in fish tissues showed a species-specific bioaccumulation pattern. Statistically significant differences were observed in the mean metal concentrations with lower bioavailability in M. cephalus compared with O. niloticus in internal vital organs (liver, kidney, and muscle) but much higher in external organs (gill and skin). Histopathological alterations and evident damages were observed in gill, liver, and kidney of both species collected from Lake Qaroun and Qaroun fish farms compared with those from the reference site. The results showed significant increase of plasma aspartate aminotransferase and alanine aminotransferase activity as well as creatinine and uric acid concentration in both fish species from polluted locations. The human health hazard index showed that the cumulative risk greatly increases with increasing fish consumption rate, thus yielding an alarming concern for consumer health.

Genotoxic effects of metal pollution in two fish species, Oreochromis niloticus and Mugil cephalus, from highly degraded aquatic habitats

In Egypt, Lake Qaroun and its neighbouring fish farms are in a serious environmental situation as a result of pollution by agricultural sewage and domestic non-treated discharges. The present study aims to evaluate genotoxic effects of toxic metals in cultured and wild Nile tilapia, Oreochromis niloticus and mullet, Mugil cephalus collected from these contaminated aquatic habitats, in comparison with fish from a non-polluted reference site. Heavy-metal concentrations (Cu(2+), Zn(2+), Pb(2+), Fe(2+) and Mn(2+)) in water and sediment samples were recorded. The condition factor (CF) was taken as a general biomarker of the health of the fish, and genotoxicity assays such as the micronucleus (MN) test and a DNA-fragmentation assay were carried out on the fish species studied. In addition to micronuclei, other nuclear abnormalities (NA) were assessed in fish erythrocytes. Degradation of the studied aquatic habitats revealed species-specific effects. A significant decrease in CF values associated with a significant elevation in MN and NA frequencies was observed in fish collected from the polluted areas compared with those from the reference site. Moreover, mixed smearing and laddering of DNA fragments in gills and liver samples of both fish species collected from the polluted areas indicate an intricate pollution condition. Results of the present study show the significance of integrating a set of biomarkers to identify the effects of anthropogenic pollution. High concentrations of heavy metals have a potential genotoxic effects, and genotoxicity is possibly related to agricultural and domestic activities.

Risk assessment of polychlorinated biphenyls (PCBs) and trace metals in River Nile up- and downstream of a densely populated area

Cairo city is the largest populated area along the whole course of River Nile with a wide range of anthropogenic activities. Efforts to restore fish habitat and recreational use of the river have raised concerns about its water, sediment and biota quality. This study provides a baseline data on the levels of PCBs and trace metals in River Nile along Cairo sector and implements the formulation of monitoring activities of the river’s pollution status. Water, sediment and Nile tilapia (Oreochromis niloticus) samples were collected during summer season, 2013 from two sites, up- and downstream, for detection and determination of 11 PCB congeners (PCBs 28, 44, 52, 70, 101, 105, 118, 138, 152, 180 and 192) as well as six trace metals (Cu, Zn, Mn, Cd, Pb and Fe). Evidences of long- or short-term exposures to these contaminants as well as its accumulation tendency were assessed by integrating the obtained analytical results of biotic and abiotic components of this aquatic ecosystem. All calculated lifetime cancer risk values for PCBs showed unacceptable risk of cancer for human consumers at both normal and subsistence fish consumption rates. The calculated hazard index for total PCBs indicates that fish are not safe for human consumption except in site 1 at normal consumption rate. Meanwhile, trace metals do not pose unacceptable risks at both consumption rates except for Pb in site 1 at subsistence consumption rate.

The use of biotic and abiotic components of Red Sea coastal areas as indicators of ecosystem health.

A biomonitoring study was conducted using some biotic (Pomadasys hasta and Lutjanus russellii fish) and abiotic (water and sediment) components of the Red Sea coast of Hodeida, Yemen Republic along two polluted sites (Al-Dawar beach and Urj village) in comparison to a reference site (Al-Nukhailah beach). The studied fish biomarkers included hepatosomatic index (HSI), condition factor (K), scaled mass index (SMI), catalase, glutathione-S-transferase (GST), malondialdehyde (MDA), total protein and albumin. In addition, metals (Fe, Cu, Zn, Pb and Cd) concentrations in water and sediment were measured and sediment pollution assessment was carried out using contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI) and enrichment factor (EF). The studied metals concentration in water and sediment samples showed significant increase among the polluted sites in comparison to the reference site. Sediment pollution assessment generally confirmed that Urj village was the most contaminated site followed by Al-Dawar beach. Catalase, GST and MDA proved to be the most responsive biomarkers with increased values of GST and MDA at sites influenced by agricultural, urban and industrial activities while catalase, HSI, K, SMI, total protein and albumin showed the opposite trend. This study recommends monitoring of sediment Igeo and EF values as well as SMI, catalase, GST and MDA as sensitive indicators of different anthropogenic activities and their effects on aquatic ecosystems under complex and different gradients of metal pollution. In addition, P. hasta proved to be more sensitive towards the detected pollution condition.

Risk assessment of polycyclic aromatic hydrocarbons (PAHs) in River Nile up- and downstream of a densely populated area

ABSTRACT A biomonitoring study was conducted to evaluate levels of eleven polycyclic aromatic hydrocarbons (PAHs) in water, sediment and wild Nile tilapia (Oreochromis niloticus) samples collected up- and downstream of Cairo sector of the River Nile, Egypt. The scaled mass index (SMI), as a fish body mass-length relationship, performed better in indicating the ecosystem and fish conditions. The total PAHs in water samples had a range of 0.0156–0.0269 mg/L, while that in sediment samples ranged from 0.723 to 1.078 mg/kg dry weight and that in fish muscles ranged from 4.065 to 10.033 mg/kg wet weight. Pollutant source appraisal was determined by diagnostic ratios and proved the predominance of pyrogenic sources in water, petrogenic sources in fish, and mixed source origin in sediment. Human health risks associated with fish consumption showed that non-cancer adverse health effects are not expected to occur but the calculated lifetime cancer risk (LCR) for the total PAHs proved that the fish muscles are not safe for human consumption at both sites. Regular monitoring programs and mitigation efforts should be considered in the near future along such areas heavily influenced by human activities.

Assessment of Ecosystem Condition Using Some Biotic and Abiotic Components along Ashtoum El-Gamil Protected Area, Lake Manzala, Egypt = تقييم حالة النظام البيئي باستخدام بعض المكونات الحيوية واللاحيوية بمحمية أشتوم الجميل، بحيرة المنزلة، مصر

The present field investigation considers monitoring some biotic (four fish species and plankton) and abiotic (water and sediment) components as indicators of natural and anthropogenic impacts on aquatic ecosystem during winter and summer seasons. This included measurement of metal concentrations in water, sediment and plankton samples, conducting a risk assessment of sediment pollution and evaluating fish body condition indices as well as oxidative stress biomarkers. The detected seasonal variation among these parameters showed site-related and species-specific patterns. The levels of metal in plankton samples were, in most cases, higher than those in sediment samples and the lowest levels were detected in water samples. Heavy metal enrichment status in sediment showed mostly a progressive pollution condition during summer as well as seasonal fluctuation in levels of Zn and Pb along the studied sites. The scaled mass index (SMI), as a fish body mass-length index, performed better in indicating the fish body condition in relation to the ecosystem condition, where it showed significant increase in case of the flathead mullet (Mugil cephalus) and the green tilapia (Tilapia zillii) during summer and significant increase in the Nile tilapia (Oreochromis niloticus) and the catfish (Clarias gariepinus) during winter. Mullet showed the highest levels of oxidative stress biomarkers (superoxide dismutase, catalase and malondialdehyde), while Nile tilapia showed the lowest levels. The present study affirms the significance of monitoring sediment geoaccumulation index (Igeo) and pollution load index (PLI) as well as SMI and oxidative stress biomarkers as sensitive indicators of intricate pollution conditions and their effects on aquatic ecosystems.

The Use of Effective Microorganisms (EM) as a Probiotic on Cultured Nile Tilapia, Oreochromis Niloticus = استخدام الكائنات الدقيقة الفعالة كمحفزات بيولوجية على أسماك البلطي النيلي (Oreochromis Niloticus) المستزرعة

Nowadays, and due to different anthropogenic activities, the environmental conditions deteriorate and consequently productivity of cultured and wild fish decreases. The present study highlights the role of effective microorganisms (EM) as a probiotic in enhancing biological features and growth performance of the cultured Nile tilapia (Oreochromis niloticus) exposed to copper metal under experimental conditions. Other metals that may interfere with toxic effects of copper on fish were measured. The conducted toxicity test showed that the copper 96hr LC50 is 6.30 mg/l, thus fish of the experimental groups were exposed to 0.1 of that dose (0.630 mg/l) as a sublethal chronic dose for 12 weeks. After this long-term exposure period, metal concentrations in gills, liver, kidney, muscles and skin of O. niloticus showed significant increase in the copper exposed group associated with histopathological changes and clear damage in gills, liver and kidney tissues comparing to the EM exposed group. Moreover, the results revealed significant improvement in growth indices, histological and biochemical aspects of EM exposed fish. The present study recommends the use of effective microorganisms in fish farms to enhance fish productivity and reduce the toxic effects of pollutants.

Water cytotoxicity and dioxins bioaccumulation in an Egyptian delta wetland ecosystem

Manzala Lake, as one of the main Egyptian wetland ecosystems, is facing risks of pollution. An in vitro cytotoxicity test using a mammalian cell line was employed to determine the toxicity of multiple pollutants in the water and Tilapia zillii fish sampled from the lake. The concentrations of seven polychlorinated dibenzo-p-dioxins and ten polychlorinated dibenzofurans were investigated in water and muscle of the fish in 2014. Cytotoxicity testing showed that the percentage inhibition of cell viability in the studied sites ranged between 56.16% and 83.22%. Dioxin analysis indicated that the average concentrations of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzofuran and 1,2,3,4,6,7,8,9-octachlorodibenzofuran were higher than the toxic equivalence quotients (TEQs) set by the World Health Organization (WHO) in all water and fish muscle samples; however, the average concentration of 2,3,7,8-tetrachlorodibenzofuran was higher only in fish muscle samples. The bioaccumulation factor (BAF) ranged dramatically between 2 and 58.5 for the detected dioxins. Adverse human health effects through the consumption of fish are not expected, because dioxin levels in fish muscle are deemed safe for human consumption. Implementation of a strategic multidisciplinary action plan is strongly recommended to sustain this delta wetland ecosystem.