Emergence patterns and microhabitat preference of aquatic dance flies (Empididae; Clinocerinae and Hemerodromiinae) on a longitudinal gradient of barrage lake system

Abstract

a b s t r a c tAquatic dance flies (Empididae; Clinocerinae and Hemerodromiinae) are important components of freshwater assemblages, especially in running waters. They are predators as larvae and adults and thus essential for understanding aquatic food webs. This study was conducted in Plitvice lakes National Park (Croatia) representing a wide variety of freshwater habitats (springs, streams, lakes and tufa barriers). Adults were collected monthly from March 2007 until March 2009 using pyramid-type emergence traps at 13 locations. A total of 3865 specimens comprising 18 species were collected. The dominant genus was Chelifera, while the most abundant species was Hemerodromia unilineata. All species were univoltine except Chelifera precabunda, Chelifera pyrenaica and Chelifera stigmatica that were bivoltine. Considerable differences in composition and structure of aquatic dance flies assemblages were recorded along a longitudinal gradient of studied sites, primarily related to differences in physical and chemical parameters of water. Water temperature was the main factor influencing the timing of emergence. Hemerodromia species preferred variable water temperature throughout the year while the majority of the Chelifera species preferred stable water temperature characteristic of spring sites. Furthermore, discharge affected assemblage composition of aquatic dance flies. The highest abundance of aquatic dance flies was recorded in lotic habitats with fast water current over substrates of moss, gravel and particulate tufa with detritus. These results give a new insight on microhabitat preference and their distribution on unique karstic habitats.

Environmental drivers influencing stonefly assemblages along a longitudinal gradient in karst lotic habitats

“…low water temperature and high oxygen concentration; Hynes, 1976;Fochetti and Tierno de Figueroa, 2008;Zwick, 2011) and the wide range of suitable habitats (Riđanović and Božićević, 1996;Miliša et al, 2010). The differences in abundance and taxa richness between the two studied years could be attributed to the variability of environmental conditions, especially water temperature and discharge, as already shown in some other studies (Zwick, 2011;Ivković et al, 2012Ivković et al, , 2014Vilenica et al, 2017a). As the majority of stonefly species prefer the headwaters of lotic habitats (Graf and Schmidt-Kloiber A, 2003;Graf et al, 2009Graf et al, , 2017, taxa richness generally decreased downstream as expected and supported by preliminary studies (Vannote et al, 1980;Sivec, 2009, 2011b).…”

“…Higher water temperatures were already recorded as causing an earlier start in emergence (Illies, 1971;Harper and Peckarsky, 2006;Zwick, 2011). Several long-term studies have shown that discharge patterns are one of the most important factors influencing changes in aquatic insect assemblages between years (Wagner and Schmidt, 2011;Ivković et al, 2012Ivković et al, , 2014Vilenica et al, 2017a). Differences in stonefly abundances between the two studied years could therefore be related to a higher discharge in 2008 which caused a more prominent downstream larval drift (Sertić Perić et al, 2011), resulting in a lower number of emerging adults.…”

“…Specific geology and hydrology of these habitats, including vast array of available microhabitats, resulted in high level of speciation and endemism, which is why karst habitats were recognized as biodiversity hotspots (Bonacci, 2009;Ivković and Plant, 2015;Previšić et al, 2014). Nevertheless, ecology of their biota, including stoneflies, is still highly understudied (Previšić et al, 2007;Ivković et al, 2012Ivković et al, , 2014Šemnički et al, 2012;Čmrlec et al, 2013;Vilenica et al, 2017a).…”

Chaetopteryx bucari sp. n., a new species from the Chaetopteryx rugulosa group from Croatia (Insecta, Trichoptera, Limnephilidae) with molecular, taxonomic and ecological notes on the group

“…In one spring (Pecki spring, Banovina region) (Table 1) we installed 5 pyramid-type emergence traps in 2010 and 2011 to investigate the emergence dynamics of caddisflies (Figure 1). This investigation is part of a multi-year study on emergence dynamics of aquatic insects in springs and other aquatic habitats in Croatia and the Dinaric karst of the Balkan Peninsula (Bosnia and Herzegovina) (Kučinić 2002, Previšić et al 2007, Ivković et al 2011, Semnički et al 2011, 2012, M. Kučinić unpublished data). The emergence trapping methodology was presented in detail by Kučinić (2002) and Previšić et al (2007).…”

Two new species of Chelifera Macquart from China (Diptera: Empididae)

“…For detailed description of the genus see Collin (1961) and Yang & Yang (2004). The adults of Chelifera occur mainly near running waters on riparian vegetation and stones where they prey on Chironomidae, Mycetophilidae and other small insects, while the larvae live in all sorts of freshwater microhabitats, such as sand, gravel, macrovegetation and mosses where they prey on chironomid and simuliid larvae (Horvat 2002;Ivković et al 2012). …”