Abstract
The large number of pollutants discharged into the aquatic environment may influence the physicochemical and biological qualities of the aquatic ecosystem. This study discloses the global quality of the surface waters and the effect of physicochemical variables on the abundance of the African freshwater crab Potamon algeriense inhabiting Zegzel watercourse, a mountain stream in the northeast of Morocco. Physicochemical variables including streamflow, water temperature, pH, dissolved oxygen, suspended matter, chloride, calcium, magnesium, ammonia, nitrite, nitrate, orthophosphate, and organic matter were evaluated monthly for one year (October 2017-September 2018). The evaluation of the physicochemical quality showed that the waters of all the stations studied are between the excellent and good quality classes concerning all the physicochemical variables and highlights also two variations with a tendency towards degradation, one spatial from upstream to downstream and the other seasonal from the wet to the dry period. The abundance of crabs was recorded to exhibit a positive correlation with dissolved oxygen, calcium (N = 44) (p < 0.01), and magnesium. However, a negative correlation has been noticed for streamflow (N = 1) (p < 0.01), water temperature, pH, suspended matter, chloride, ammonia, nitrite, nitrate, orthophosphate, and organic matter. The results obtained reveal that besides the biotic variables, the distribution of P. algeriense also depends on these specific environmental variables.
Highlights
Freshwater quality deserves special attention because it is a vital resource, and it has recently been much altered and seriously threatened by human activities such as physicochemical and biological pollution caused by runoff from agricultural and urban areas and the overexploitation due to the anarchic water diversion.Pollution of aquatic bodies has caused several environmental problems, such as the disappearance of biodiversity and aquatic ecosystems [1]
Crustaceans are highly sensitive to pollution [2, 3], and their abundance and existence depend on particular environmental variables such as pH and dissolved oxygen [4, 5]
Studies on the determination of correlation between abiotic factors and crab populations seem to be imperative to evaluate the effects of extremes of physicochemical variables on species and provide information regarding the optimum conditions under which crabs can reproduce and maintain the population
Summary
Effects of Physicochemical Variables of Superficial Waters on the Abundance of the North African Freshwater Crab Potamon algeriense (Bott, 1967). Soufiane Fadlaoui ,1 Ouahid El Asri ,2 Mustapha Bouterfas, and Mohammed Melhaoui. Received 22 October 2020; Revised 29 January 2021; Accepted 9 March 2021; Published 16 March 2021
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