engleski

The role of crenal morphology in shaping water mite (Acari: Hydrachnidia) assemblages in karst springs

Many studies emphasized the role that water mites play within the invertebrate communities of spring habitats, both regarding species diversity and the significance within the crenal food web. In undisturbed natural springs with permanent surface or subterranean flow, water mites are nearly always present and usually display high diversity. This study aimed to determine whether significant differences in water mite assemblages between rheocrene and limnocrene karst springs could be detected in terms of species richness, diversity and abundance, but also in different ratios of specific synecological groups: crenobiont, crenophilous and stigophilous water mite taxa. Our research was carried out on four limnocrene and four rheocrene karst springs in the Dinaric karst region of Croatia. Seasonal samples (20 sub-samples per sampling) were taken at each spring during 2014 with a 200 µm mesh net, taking all microhabitat types with coverage of at least 5% into consideration. Water mite abundance was found not to differ between morphological spring types. The higher values of species richness and diversity indices, usually associated with rheocrenes, were indeed significantly higher in rheocrenes when compared to limnocrenes. The higher shares of crenophilous and crenobiont water mite individuals were in this case found in limnocrenes. A higher ratio of stygophilous taxa was found in rheocrenes indicating a higher degree of groundwater/surface water ecotone influence. Within this research, 40% of identified water mite species (eight out of twenty) were recorded for the first time in Croatia, thus highlighting a huge gap in water mite knowledge of Croatian karst springs.

water mites ; rheocrene spring ; limnocrene spring ; ecotone ; crenobionts

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