Mayflies (Ephemeroptera) of Rhithral and Crenal Zones of Donetsk Elevated Physiographic Area’s Watercourses (Eastern Ukraine): species composition, ecological characteristics

Abstract

One third of species of Eastern Ukraine’s mayfly fauna develop in coldwater watercourses of Donetsk Elevated Area. Ten species develop in rhithral streams of area and only two in crenal ones. A number of species are presented in area by the populations isolated from main parts of them areals (Alainites muticus, Serratella ignita). Areal of Ecdyonurus dispar gratificus is limited by the area under investigation, where the larvae of this species inhabit pure rhithral watercourses mainly. Larvae of the species which inhabit rhithral zone of region’s streams, are attributed to four types of ecomorphs and take part in formation of different types of the communities. Larvae of each species demonstrate their own stational preferences, which depend on their ecomorphological characteristics. Quantitative ratio of mayflies’ larvae of different species and their types of ecomorphs change considerably during the year. Competition between the species which prefer the same microstations is reduced due to displaced life cycles. In the result, the maximums of biomass and population size of these species are almost never observed simultaneously. Considering that the anthropogenic changes and pollution of rhithral zone of model watercourses is almost absent, their mayfly species composition, the change of quantitative ratio of different species’ larvae during a year, the features of stational distribution and the structure of communities could be considered as model ones in indicative researches on the rhithral zone of Donetsk Elevated area

Keywords

• Ephemeroptera
• Eastern Ukraine
• rhithral
• crenal
• stational distribution
• communities
• interspecific competition