Habitat characteristics for different freshwater snail species as determined biologically through macroin- vertebrate information

Macro-invertebrates including freshwater snails collected from 643 sites over 8 successive seasons among the River Nile, branches, main canals and certain drains in eight Egyptian Governorates. Thirteen snail species and one bivalve species were identified. The most distributed were Lanistus carinatus and Physa acuta while the most abundant were Cleopatra bulimoides and Physa acuta during the whole study. The sites that harbored each snail species in all the examined watercourses were grouped seasonally and their biological assessment was determined by their minimum and maximum total point similarity percentage to that of the corresponded reference site and mean of the total points. Habitats for most snail species attained minimum total point's similarity percentage less than 21% [very poor habitat] during autumn and winter then spring while during summer very poor habitat was harbored by only few snail species. P. acuta was the only survived snails in habitat which attained 0 as a minimum total point's similarity percentage during two seasons and L. carinatus and Succinea cleopatra during one season. With respect to medically important snails very poor sites constituted 23% of Biomphalaria alexandrina sites, 14% of Lymnaea natalensis and 9.4% of Bulinus truncatus sites. The studied macroinvertebrate matrices, total number of organisms, taxa richness, the Ephemeroptera, Plecoptera, and Trichoptera [EPT] index, ratio of EPT index to chironomidae, ratio of scraper to filtering collector, contribution of dominant macroinvertebrate major group, comparison revealed descending tolerances from B. alexanrina followed by L. natalensis then B. truncates, but Hilsenhoff Biotic Index [HBI] showed the same tolerance to organic pollution

Impact of water quality and soils on the molluscicidal activity of the plants A gave attenuata and A gave fihifera

The effect of water quality, salinity, an organic compound [Na[2]EDTA] and soil types [alluvial and sandy] on the molluscicidal activity of the two plants A gave attenuata and A gave filjfera against Biomphalaria alexandrina snails under laboratory conditions were studied. The LC[50] of the two tested plant molluscicides against B. alexandrina in all tested water samples [Nile, irrigation and drainage water] were lower than the tap water [as a control]. Thus, the molluscicidal activity of the two plants slightly increased when tested at the studied water samples. LC[50] values of the plant A. altenuata against B. alexandrina for the Nile water and drainage water were 50 and 54.5 ppm, respectively compared to 68 ppm for tap water. The corresponding values of A. fiIfera were 50, 54.5 and 60 ppm respectively. The molluscicidal activity of the two tested plants was not affected by the salinity levels used. Slight effect of the organic compound Na[2]EDTA on the molluscicidal activity of the two plants was recorded. However, the tested soils [alluvial and sandy] had a significant reduction in molluscicidal activity of A. attenuata and A. filifera against B. alexandrina. Thus, only 20% mortality of treated snails was recorded for LC[50] of A.attenuata in the presence of sandy soil, while no death was observed at alluvial soil. TLC analysis reveled only three bands for A. alt enuata mixed with sandy or alluvial soil compared to 6 bands for the crude plant. For A filifera only two bands appeared by mixing with sandy soil, whereas with alluvial soil no bands appeared

Feeding ecology and Food compostition of the black carp mylopharyngodon piceus and the grass carp ctenoph -aryngodon idella inhabiting the fish pond of Al - Abbassa fish hatchery with emphasis given to vector snails

In this study, the stomach contents of M. piceus and C. idella collected from earthen fish ponds at Al-Abbassa Fish Hatchery during different seasons were examined. Food items were analyzed by three methods, including the numerical percentage [N%] of point assessment [P%] and frequency of occurrence [F%]. A comparison of the different methods emphasized the importance of snails as the major food resources in the diet of M. piceus during all seasons. During winter, the stomachs of the most fish samples collected from fish ponds were empty or had traces of food. The index of relative importance [IRI] indicated that the snails were the major food category in the diet of M. piceus during summer, autumn and spring represented by 7331, 9696 and 11670, respectively. Plants were the main food item in the diet of C. idella during summer [4604], meanwhile they ranked the 3rd in the relative importance in the diet during autumn and spring. Artificial fish food came as the 2nd food item in the diet of M. piceus during summer [1398.9] and autumn [5896.3], but it was completely absent in spring. It is considered the main food item in the diet of C. idella during autumn [10384.3] and spring [6293.5] and ranked the 3rd in summer [1395.5]