engleski

The influence of some biotic and abiotic factors on abundance of aquatic Dance flies ((Empididae: Clinocerinae, Hemerodromiinae) in emergence traps)

The effect of water velocity and available amount of prey on the abundance of emergent aquatic Dance flies was studied at different karstic microhabitat types. Study was performed at nine locations in the National park Plitvice Lakes, which is situated in a karst region of Croatia. Six pyramid-type emergence traps were placed at each investigated site. Specimens were collected monthly from March 2007 till February 2009. In total 3597 specimens were identified belonging to 20 species ; four of them are a new record for Croatian fauna (Chelifera pyrenaica Vaillant, 1981, Hemerodromia laudatoria Collin, 1927, Clinocera wesmaeli (Macquert, 1835), Wiedemannia (Philolutra) aquilex (Loew, 1869)). Correlation index showed positive correlation between water velocity and abundance of aquatic Dance flies ; if the water velocity is higher, abundance of Dance flies is higher as well. Positive correlation was also observed between amount of prey (Chironomidae and Simuliidae) and dance flies ; with more prey the abundance of aquatic Dance flies is greater. One way ANOVA showed significant difference between silt and other type of microhabitats (moss, dead tufa parts with leaf litter and gravel) ; aquatic Dance flies prefer other types much more then silt. In conclusion, aquatic Dance flies prefer microhabitats with strong water velocity, high amount of prey and therefore microhabitats types such as moss, gravel and those with organic deposits.

aquatic Empididae; water velocity; microhabitat types; prey abundance; emergence traps

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