Family variation of aquatic insects and water properties to assess freshwater quality in El-Mansouriya stream, Egypt

摘要

The use of family variation of aquatic insects in assessing freshwater quality in ecosystems has only recently been applied in the northern parts of Africa. The current study along with El Husseiny et al. (2015) and Bream et al. (2017) can be considered the first of such studies in Egypt. The survey was conducted during the period April 2015 to February 2016, in the permanent stream, El-Mansouriya, in Dakahlia province, Egypt. The water quality and health status of water for human use of this stream was determined using different aquatic invertebrate family biotic indices formulations (BMWP, SWRC and EPT indexes) along with the physical and chemical properties. Water samples were analysed and the water quality parameters were compared to the WHO (2004) standards. Most of the parameters were found to be within permissible limits, except for turbidity and nutrient salts. Aquatic insects were collected and identified to order and family levels. A total of seven orders and 19 families were collected, including a few intolerant insects (EPT orders) and insects more tolerant to pollution (chironomid larvae). The values of the water quality parameters sampled showed significant correlations with aquatic insect diversity. The canonical correspondence analysis clarified that the electrical conductivity of the water was the most significant variable affecting the variation in taxa. From these results it can be seen that the water quality of this stream is moderately impacted, and could therefore be considered harmful, since this stream is the main supply to theWater Central Station in Aga. Water quality degradation is generally due to impacts associated with population growth, industrialisation and agricultural activities. These results can be used to assist in conservation planning and decision-making in Egypt.