Stonefly Assemblages as Indicators of Relict North African Mountain Streams (Plecoptera)

The stoneflies of the Maghreb (Tunisia, Algeria and Morocco) are characterized by high endemicity but their ecology remains poorly known. We have surveyed the stonefly assemblages of northeastern Algeria mountain streams, a relatively unstudied region, and attempted to identify through co-inertia analysis the environmental correlates of their distribution. Species richness varied from nine taxa in the most species-rich localities to a single taxon in some anthropogenically impacted localities. Results indicated a significant co-structure between ecological descriptors and stonefly distribution and frequency of occurence. Mountain stream stonefly assemblages differed according to water conductivity, altitude, anthropogenic impacts, and spring proximity. The frequent occurrence of Afroperlodes lecerfi, Brachyptera auberti and Tyrrenoleuctra tangerina was indicative of high altitude, intermittent streams whereas Amphinemura berthelemy, Eoperla ochracea and Leuctra sartori favoured permanent, low-altitude headwaters. Conversely, Leuctra cf. vaillanti seemed to tolerate low altitude sites characterized by high water conductivity, large bed width and fast flow. This study also highlights the diversity of the Maghrebian endemic or microendemic stoneflies harbored by relict lotic streams and their sensitivity towards anthropogenic stressors.