Spatial patterns of Trichoptera diversity and assemblage structure in the Mediterranean Dinaric karst intermittent rivers in the Western Balkans

Abstract

Intermittent rivers are hydrologically extreme freshwater systems that periodically cease to flow. Such habitats occur worldwide, but they are most common in semi-arid regions of the world, such as the Mediterranean region. Trichoptera are frequently used in biomonitoring programmes worldwide. However, their biodiversity and ecological requirements in intermittent Mediterranean karst habitats are still poorly understood. Here, we provide data on Trichoptera assemblage metrics (taxa richness, diversity and abundance), assemblage structure (trophic structure and stream zonation preference), and their relationship with environmental variables in the lotic phase of four intermittent rivers in the Dinaric karst region of the Mediterranean in the Western Balkans. Due to the extreme hydrological conditions in the studied habitats, Trichoptera showed a low taxa richness (10 taxa). The highest diversity was recorded in rivers with greater habitat heterogeneity. In addition, rivers with higher conductivity and water temperature, and lower water velocity had more diverse assemblages. The trophic structure and stream zonation preferences of Trichoptera were significantly different among the intermittent rivers studied, with the influence of anthropogenic activities evident in certain rivers. However, the variability of Trichopteran assemblages along the course of each intermittent river, was generally low, which could be attributed to the uniform microhabitat composition and physico-chemical water parameters in the studied rivers. The results of this study could provide a valuable background for further research and the development of conservation measures for both Trichoptera and intermittent karst habitats in the Mediterranean.