The significance of Mayflies (Insecta: Ephemeroptera) in mountainous and semi-mountainous rivers from watersheds within the West Aegean basin

Rimcheska, Biljana and Vidinova, Yanka (2025) The significance of Mayflies (Insecta: Ephemeroptera) in mountainous and semi-mountainous rivers from watersheds within the West Aegean basin. In: 14th Symposium for European Freshwater Sciences - SEFS 14, 20-25 07. 2025, Boly, Türkiye.

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Abstract

The mayflies (Ephemeroptera) are among the most abundant benthic invertebrates associated with natural running freshwaters. They inhabit a variety of environments and show a high sensitivity to anthropogenic pressure. Therefore they are often used as bio-indicators of freshwater health. Mayfly assemblages vary depending on the environmental, geographic and hydrological conditions along latitudinal gradient and the negative impacts on river watersheds. Nevertheless, the diversity and abundance of these communities and their ecological preferences in the mountainous and semi-mountainous streams and rivers across Balkans are yet insufficiently studied. We analysed mayfly assemblages, their microhabitat preferences in R3- (mountainous) and R5- (semi-mountainous) river types, as well as correlations between the relative abundance and species diversity both per site and season and accounting for water quality in spatial and temporal scale. In total 69 samples from 38 sites (Struma, Mesta and Vardar River basins) were collected in autumn 2017 and spring 2018. We reveal the characteristic elements of the mayfly fauna from representative sites of studied river types. Variation in species diversity, total and relative abundance, and the similarity in assemblage composition between/within studied basins were analysed. A total of 59 morphologically distinct mayfly taxa (from total 280 macroinvertebrate taxa) belonging to 18 genera and eight families were identified. Thus, mayfly taxa dominated the macroinvertebrate communities. The dominant taxa were Baetis rhodani (37 sites), B. muticus (36 sites) and the genus Ecdyonurus (35 sites). Minor differences in number of taxa, total and relative abundance and species diversity were noted between seasons and river types, mainly as the sites' seasonality was not influenced by the low water level in autumn, but by reach-scale microhabitat diversity. We observed a positive correlations (0.45) between relative abundance and the number of taxa per site. Mayfly species diversity was influenced by substrate heterogeneity which in turn was determined by seasonality and anthropogenic activities. The species richness per river basin was high, and was highly influenced by river morphology and anthropogenic degradation of microhabitats. Struma basin had the highest taxa richness with >20 mayfly taxa, observed at four sites. Following the longitudinal gradient, we observed increasing taxa diversity, except at human-impacted sites. Mayfly taxa abundance and richness were comparable at R3- and R5- sites, likely because diverse microhabitats, higher oxygenation and water velocity, and lower water temperatures are characteristic of mountainous and semi-mountainous streams and rivers across Balkans. Their diverse mayfly assemblages, including rare and endemic species, highlight the importance of protecting such rivers from future degradation and pollution across Western Aegean basins and the wider Balkan peninsula.

Item Type:	Conference or Workshop Item (Speech)
Subjects:	Scientific Fields (Frascati) > Natural sciences > Biological sciences
Divisions:	UKLO Network
Depositing User:	UKLO Mrezha
Date Deposited:	26 Nov 2025 07:59
Last Modified:	26 Nov 2025 07:59
URI:	https://eprints.uklo.edu.mk/id/eprint/11209

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