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

Chemical and biological assessment for Egyptian surface freshwater environment with reference to human activities

The Egyptian freshwater was assessed in the River Nile, branches, main canals and certain drainages in eight Governorates, over eight successive seasons starting from spring 2008. Chemical assessment was made through ten parameters and the biological one was made through macro-invertebrates information. Results showed that means of Cd, Pb, Cu, Hg, Mn, Fe, Ni, Na, K and Ca varied in watercourses seasonally within somewhat narrow ranges, which may exceed the level of concern but with some elevations in branches, Rayahs and canals during certain seasons. Sites showed chemical levels over the permissible one or those gain total points

Molluscicidal and physiological activities of some plants against biomphalaria Alexandria snails

The molluscicidal activity of three plants: Nerium oleander, Dizygotheca elegantissima and A gave decipiens on Biomphalaria Alexandrina snails at different exposure intervals and size or age of snails was studied throughout the present investigation. Also, the effects of these selected plants on Schistosoma mansoni cercariae and miracidia were assessed. Moreover, the role of sublethal concentrations of these plants on physiological processes and functions on the hemolymph of these snails was also clarified. Results showed that N. oleander proved the most effective plant as its LC[90] was 100ppm after 24hrs from exposure compared with the values of 120 and 180 ppm with the plants D. elegantissima and A. decipiens, respectively. The elongation of remarkable exposure periods from 24 to 48 hrs increased the molluscicidal activities of the tested plants. Different sizes or ages of Biomphalaria Alexandrina snails showed different susceptibility levels towards the action of the tested plants. Newly hatched snails were the most sensitive group. When the LC[50] and LC[90] of the experimental plants were tested against the cercariae, almost 100% of cercarial mortality was obtained after only two hrs when used 100, 120 and180 ppm for Nerium oleander, Dizygotheca elegantissima and Agave decipiens, respectively. Meanwhile, 100% miracidia mortality was obtained after 1 hr when exposed to the same concentrations. Thus miracidia proved more susceptible than cercariae. While used the sublethal concentrations of these plants, the LC[0] of the three tested plants showed moderate significant increase in transaminases activities. The total protein, albumin and globulin were slightly changed; while the A/G ratio did not record any changes between treated and control snails. The application of plant molluseicides resulted in marked increase of total lipid content; the maximal observation was recorded with the use of both N. oleander, and D. elegantissima

Impact of certain plants and synthetic molluscicides on some fresh water snails and fish

The LC50 [78, 85 ppm] and LC90 [88, 135 ppm] of Anagalis arvensis and calendula micrantha respectively against Biomphalaria alexandrina were higher than those of the non-target snails, Physa acuta, Planorbis planorbis, Helisorna duryi and Melanoides tuberculata. In contrast, the LC50 of Niclosamide [0.11 ppm] and Copper sulphate [CuSo4] [0.42 ppm] against B. alexandrma were lower than those of the non-target snails. The mortalities percentage among non-target snails ranged between 0.0 and 20% when sublethal concentrations of CuSo4 against B. alexandrina mixed with those of C. micrantha and between 0.0 and 40% when mixed with A. arvensis. Mortalities ranged between 0.0 and 50% when Niclosamide was mixed with each of A. arvensis and C. micrantha. A. arvensis induced 100% mortality on Oreochromis niloticus after 48 hrs exposure and after 24 hrs for Gambusia affinis. C. micrantha was non-toxic to the fish. The survival rate of O. niloticus and G. affinis after 48 hrs exposure to 0.11 ppm of Niclosamide were 83.3% and 100% respectively. These rates were 91.7% and 93.3% respectively when each of the two fish species was exposed to 0.42 ppm of CuSo4. Mixture of sub-lethal concentrations of A. arvensis against B. alexandrina and those of Niclosamide or CuSo4 at ratios 10:40 and 25:25 induced 66.6% mortalities on O. niloticus and 83.3% at 40: 10. These mixtures caused 100% mortalities on G. affinis at all ratios. A. arvensis CuSo4 mixtures at 10:40 induced 83.3% and 40% mortalities on O. niloticus and G. affinis respectively and 100% mortalities on both fish species at ratios 25:25 and 40:10. A mixture of sub-lethal concentrations of C. micrantha against B. alexandrina and of Niclosamide or CuSo4 caused mortalities of O. niloticus between 0.0 and 33.3% and between 5% and 35% of G. affinis. The residue of Cu in O. niloticus were 4.69, 19.06 and 25.37 mg/ l kgm fish after 24, 48 and 72 hrs exposure to LC0 of CuSO4 against B. alexandrina respectively

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]