engleski

Water mite (Acari: Hydrachnidia) survival strategies in intermittent rivers of Croatia

More than half of the global running waters are considered as intermittent or ephemeral. Nevertheless, data on ecology of aquatic macroinvertebrate assemblages are still scarce. Water mites have complex life cycles connecting them with an array of other macroinvertebrates. This complexity is even greater in intermittent rivers where they have to synchronize their long-lived life cycles according to flow intermittency as well as host, prey or habitat availability. Water mites and other macroinvertebrates were collected in eight intermittent rivers of the Adriatic drainage basin, with various hydrological regimes, using the AQEM sampling protocol. A total of 101 water mite specimens belonging to 7 genera were recorded. Their low abundance was most probably caused by harsh environmental conditions due to dry phases. The genus Hygrobates was the most abundant, occurring in most rivers, implying that this genus was the most tolerant in terms of flow intermittency demands. A single specimen from the genus Spechon, typical for spring habitats, was the rarest. Lebertia and Mideopsis were found in a river with the highest flow intermittency. These two genera showed morphological features typical for lentic habitats (swimming setae) indicating that they probably survive the dry phase in small pools. The genus Torrenticola with typical rheophilous “hard bodied” morphology was found in the river with least flow intermittency, most likely surviving the dry phase as dormant nymphs buried in the sediment. Distinct water mite morphological features suggest the development of different survival strategies in overcoming flow intermittency and resulted in relatively high taxa richness.

water mites, Hydrachnidia, Intermittent rivers, IRES

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