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Mounira H, Fatiha BS, Noureddine S. 2023. Impact of physicochemical parameters of water on the biodiversity of the invertebrate fauna from Echatt Lake (Northeast Algeria). Biodiversitas 24: 258-268. Algeria is a case study of biodiversity ignorance. To date, there are neither complete inventories for any taxa nor atlas across the country! Yet, Algeria is of great importance for global biodiversity. The coastal area of Algeria is part of the global biodiversity hotspot which is the Mediterranean perimeter and has several regional red spots of biodiversity. Biodiversity provides raw material resources necessary for living beings' survival and maintaining atmospheric quality, climate regulation, water quality, and soil fertility. In addition, macrobenthic fauna is an important provider of aquatic ecosystems. The present study aimed to determine the biodiversity of the invertebrate community from Echatt Lake (Northeast Algeria) located in a protected area classified by Ramsar in 1983, and to evaluate the impact of anthropogenic activities using water physicochemical parameters on their structure and function. Samples were collected monthly over one year (January 2019-December 2019) at four selected stations, and 2,861 specimens were collected. The identified species (16 species) belong to 9 families: Naucoridae, Hydrophilidae, Notonectidae, Pleidae, Corexidae, Eylaidae, Pionidae, Daphniidae, and Copepoda. Seven physicochemical parameters (temperature, hydrogen potential, electrical conductivity, hydrometric title, alkalimetric title, complete alkalimetric titer, and turbidity) of the water were also determined in each station to evaluate their influence on the abundance and distribution of the invertebrate fauna. The pH and the apparent turbidity influence the invertebrate fauna, while the richness was relatively low at stations 2 and 4, located near anthropogenic sources of pollution. The data obtained permitted us to evaluate the possible impact of anthropogenic activities on the biodiversity of invertebrates.

International audience

ISSN: 2152-2197 ; ESSN: 2152-2219. Editeur commercial : Scientific Research Publishing; International audience; Diflubenzuron (DFB, trade name dimilin® 25 WP) is a chitin synthesis inhibitor widely used against forest insect pests in Algeria. Prior to implementation of these products as chemical agents for mosquito control, knowledge on their potential effects on non-target organisms and its behaviour in water are needed. Therefore, the present study was focused on DFB and aimed to use an HPLC procedure developed previously in order to obtain information on its degradation in freshwater and its bioconcentration in adult females of the fish Gambusia affinis (Cyprinodondiformes, Poeciliidae), which is one of the best candidates fo r biological control programs against mosquitoes. The adult females were exposed to dimilin ® (initial concentration 312 ng a.i./ml) for 28 days and residues analysis determined at different exposure times (0, 7, 14, 21 and 28 days). The concentration of DFB in freshwater decreased with exposure time while the amount of residues detected at the surface of the fish body increased progressively to reach a maximum at day 14 (162.7± 14.0 ng/fish) and declined thereafter during the exposure period. In addition, DFB incorporation into body increased with decreasing DFB concentration in water at each exposure time. The following average distribution was noted at the end of experiment (28 days): about 33% of the applied concentration was detected on the surface of fish body and was recovered by simple rinsing, and about 67% was found inside the fish body. A degradation in water and surface of fish occurred starting day 14 during the experimental period. Thus, about 40% of the initial concentration was degraded in freshwater after 28 days. The results are discussed to develop a better understanding of the degradation of dimilin in water and their potential effect on non-target organisms for its application for controlling mosquito.