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Biomonitoring of radioactive contamination using benthic invertebrate communities in Manzala Lake, Egypt

Imam Noha, Bendary Reda E.

Oceanological and Hydrobiological Studies

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2023

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Vol. 52, No. 2

147--165

EN

Manzala Lake, the largest in Egypt’s Nile Delta, hassignificant human activity. The Lake’s ecological conditionhas recently been impacted by a significant increase inagricultural, industrial, and urban wastewater discharge. Avaluable tool for monitoring the water quality of ManzalaLake is the sensitivity of invertebrate species to varioustypes of pollution, such as radioactive contamination.Activity concentrations of radionuclides Radium-226 (226Ra),Thorium-232 (232Th), Potassium-40 ( 40K), and Caesium-137(137Cs) were measured in water, sediments and benthicinvertebrate samples in 2020. The benthic community’sspatial distribution and the radionuclides’ bioaccumulationwere evaluated to determine possible relationships.Thirty taxa of benthic invertebrates were recognised.The data illustrated that the mean activity concentrationof radionuclides in water was in the order of 40K > 232Th >226Ra > 137Cs, which changed into 40K > 226Ra > 232Th > 137Csin the sediment and benthic invertebrates. Gastropodaand Ostracoda are the dominating groups of benthos inthe lake and are related to the highest concentrations ofradionuclides. The benthos species with shells dominatedat the sites with the highest activity concentration of 226Ra,while soft-bodied organisms dominated in sites with thehighest average 137Cs activity in these samples.

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Impact of water salinity on long-term dynamics and spatial distribution of benthic invertebrates in the Small Aral Sea

Krupa Elena, Grishaeva Olga

Oceanological and Hydrobiological Studies

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2019

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Vol. 48, No. 4

355--367

EN

In 1996–2008, macrozoobenthos of the Small Aral Sea was investigated. A total of 320 macrozoobenthos samples were collected. Statistical analysis and statistical mapping were performed using Statistica and Photoshop software. Ten taxa of macrozoobenthos were identified, with an average water salinity of the Small Aral Sea ranging from 6.3 to 19.0 PSU. Average annual community abundance reached 1962 specimens m-2, with biomass of 107.1 g m-2. Quantitative variables of macrozoobenthos decreased by an order of magnitude by the end of the analyzed period. The polychaete Hediste diversicolor and mollusks Abra ovata, Cerastoderma glaucum, Caspiohydrobia sp. were the dominant taxa. Statistical mapping and correlation analysis revealed that the high biomass of A. ovata and Caspiohydrobia sp. occur in areas with high water salinity. Aggregations of the mollusk C. glaucum were observed in various areas of the sea. The polychaete H. diversicolor preferred areas with relatively low salinity. Analysis of the results showed that the optimum salinity gradient with Aral salt composition was 17–27 PSU for A. ovata, Caspiohydrobia sp. and C. glaucum, while 1–27 PSU for H. diversicolor. Along with changes in water salinity, the currently growing pressure from freshwater fish is an additional factor affecting the structure of benthic communities in the Small Aral Sea.

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Potholes of Mountain River as Biodiversity Spots : Structure and Dynamics of the Benthic Invertebrate Community

Ren H., Yuan X., Yue J., Wang X., Liu H.

Polish Journal of Ecology

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2016

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Vol. 64, nr 1

70--83

EN

Temporary freshwater rock pools, as special, small-sized and isolated habitats, provide ideal systems for studying island biogeography and ecological theories and processes. In this study, a total of 70 potholes of mountain rivers were sampled during the four seasons from November 2013 to October 2014 to assess the structure of the benthic invertebrate community and to identify the relationships between habitat characteristics and the community composition. Pothole area ranged from approximately 0.01 to 0.39 m2, and pothole depth ranged from 0.03 to 0.74 m. Forty-three taxa belonging to 37 families and 16 orders were collected from the potholes. The highest numbers of benthic invertebrate taxa were observed in summer and the highest average number of taxa per pothole (8.5) was observed in autumn. The diversity was the highest in spring, and the average densities of benthic invertebrates were highest in autumn. Large potholes supported more taxa than small ones and significant relationships between richness and pothole area, richness and water volume were observed. The results of Redundancy Analysis show that the community composition of benthic invertebrates in the potholes was closely correlated with water temperature, pothole area and water depth. Our results indicate that benthic invertebrate communities in river potholes are mainly structured by water depth, pothole area and water volume. The seasonal changes are also an important factor determining the presence/absence of certain taxa.