engleski

Mayfly emergence patterns: a long-term study in tufa depositing habitats of the Dinaric karst

Mayfly emergence patterns and microhabitat preferences were studied in the Plitvice Lakes NP (Croatia) during a nine-year period in two types of karst freshwater habitats: a spring and two tufa barriers, using pyramid-type emergence traps. A total of nine mayfly species were recorded. Highest proportion of collected individuals belonged to the genus Baetis which was recorded at all three study sites, but we were unable to distinguish between two included species (B. rhodani and B. cf. nubecularis). Other numerous recorded species were Paraleptophlebia submarginata, Ephemera danica and Rhithrogena braaschi. Tufa barriers had higher species richness and diversity than the spring but significantly lower population densities. In NMDS analysis, the spring separated from tufa barriers. Mayfly assemblages were at all sites dominated by species typical for the rhithral zone, while in tufa barriers, potamal and littoral elements also appeared. In the studied spring, emergence mainly occurred between March and November, where the main trigger for emergence was photoperiod. In tufa barriers, emergence mainly occurred between April and July and was related to the elevated water temperature. Generally, higher abundance of emerging individuals was recorded during the years with higher water discharge. Emergence patterns of some species were in accordance with their typical Central European emergence patterns (e.g. E. danica) while some other showed certain discrepancies (e.g. Rh. braaschi). The highest species richness was recorded on moss, and the highest number of individuals on gravel/tufa. Baetis sp. preferably emerged from gravel/tufa and moss, and Rh. braaschi from vegetation (moss and macrophytes).

Ephemeroptera ; emergence ; spring ; tufa barrier

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