Macroinvertebrate diversity as an indicator of ecological health and water quality in Northern Algeria

Abstract

This s tudy aims to investigate the spatial and temporal variation of macroinvertebrate communities and their relationship with environmental factors in the rivers of Chrea National Park, northern Algeria. Analysis of the spatio-temporal variation of physico-chemical parameters revealed no significant differences in temperature between stations. However, highly significant differences were observed for pH, conductivity and dissolved oxygen. Over a four-month period, a total of 19,737 individuals were sampled at four stations. Macroinvertebrate diversity was highest in the Djir and Merdja Rivers, with Diptera dominating the community composition at most stations. However, species richness and evenness were significantly lower in the Tamesguida River, suggesting greater environmental degradation in this region. The logarithmic curve of the rank frequency diagrams shows that the Merdja and Djir Rivers have higher initial abundances than the Mouzaia. Index results diversity indices show a high biodiversity in the Djir, Merdja and Mouzaia Rivers, while the Tamesguida River has much lower values, indicating a lower diversity and a more marked dominance of certain species. The Shannon-Wiener index reaches its maximum in the Djir (2.75) and its minimum in the Tamesguida (0.87). The Standardized global biological index,the Pielou evenness index and the Simpson index follow a similar trend, showing a more balanced species distribution in the Djir and Merdja and a less balanced distribution in the Tamesguida. The Margalef index confirms a much lower species richness in Tamesguida compared to the other stations.The results indicate that the Tamesguida River has a significantly lower diversity and species richness than the other stations, with a more pronounced dominance of certain species