Tufa Barriers from a Caddisfly's Point of View: Streams or Lake Outlets?

Abstract

The caddisfly community composition in different microhabitats at tufa barriers was studied in the Plitvice Lakes NP, Croatia. Three tufa barriers were investigated and six emergence traps were installed at each site covering various microhabitats. Sampling was conducted monthly during the year 2008. Tufa barriers are lake outlet habitats, but they feature a variety of microhabitats similar to streams, which is reflected in the composition of caddisfly communities regarding longitudinal distribution preferences. The caddisfly communities at all three sites were dominated by species typical for the rhithral zone, but there was a shift in species composition along a longitudinal gradient, from the epirhithral to the metarhithral zone. Analysis of functional feeding guilds showed considerable differences between the caddisfly community at the Labudovac barrier and both downstream barriers, shifting from one with a quite diverse composition, to one completely dominated by passive filter-feeders. Passive filter feeders were not represented by the same taxa at up-and downstream barriers (i.e., by Hydropsyche species and Wormaldia species, at the Labudovac barrier and at both downstream barriers, respectively). Due to high complexity and habitat diversity, the highest diversity and equitability of caddisfly communities were recorded at microhabitats with particulate tufa and medium current velocity (10-20 cm/s). The lowest diversity and species richness were recorded for silt with low current velocity (0-10 cm/s). Abundance of caddisflies was positively correlated with current velocity due to a very high proportion of rheophilic passive filter feeders in the communities. However, community composition and structure is only to some degree influenced by microhabitat characteristics, but rather by their general position within the barrage-lake system, i.e., longitudinal distribution and thereby availability of different food resources. www.revhydro.comwith water from the Matica stream formed by merging of the streams Crna Rijeka and Bijela Rijeka in the upper section (Fig. 1). According to the Koppens climate classification, this area is influenced by temperate and continental climates. Most of the area is covered by forest consisting of Fagus sylvatica and Abies alba.The chosen study sites were located on three tufa barriers: Labudovac barrier (BL), Kozjak-Milanovac barrier (BKM) and Novakovića Brod barrier (BNB) (Fig. 1). Regarding general habitat characteristics, the uppermost Labudovac barrier differs from the two downstream barriers, mainly in its size (it covers a considerably larger area), substrate composition (there is no silt at BL, Table 1), annual water temperature and oxygen saturation range (the minimum and maximum water temperatures are slightly lower at BL than at BKM and BNB, and oxygen saturation values have a higher range at BL than at the two downstream barriers; IVKOVIĆ et al., 2012). Sampling and Laboratory MethodsCaddisflies were collected monthly during 2008 (Jan-Dec 2008) using six pyramid-type eme...

Environmental factors affecting mayfly assemblages in tufa-depositing habitats of the Dinaric Karst

“…On the other hand, tufa barriers were a more favourable habitat type than upper lotic habitats, due to the higher amount of organic matter. The barriers are situated between lakes, which is why they represent natural lake outlet habitats where organic matter accumulates, thus enhancing conditions for detritivorous insects such as mayflies (Obelić et al, 2005;Šemnički et al, 2012;Ivković et al, 2013a). Similar to the previously investigated freshwater systems of the Dinaric Karst (Vilenica et al, 2016b), water temperature and pH were amongst the most important variables that determined mayfly assemblages and their distribution (e.g.…”

“…stoneflies (Popijač and Sivec, 2009), caddisflies (Previšić et al, 2007;Šemnički et al, 2012), blackflies (Ivković et al, 2013a), aquatic dance flies (Ivković et al, 2013b) and riffle beetles (Mičetić Stanković et al, 2015). However, the ecological preferences of mayfly assemblages in this region are still poorly known (e.g.…”

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

“…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).…”

Holocene tufa in the Slovak Karst: facies, sedimentary environments and depositional history

“…The in cli na tion of some of the stromatolitic beds studied sug gests they lit tered steep stream-beds, in di cat ing the latter. This is sup ported by the com mon oc cur rence of lar val housings within stromatolites since anal o gous lar val hous ings have been: (1) found in many re cent tufas which orig i nate in fast-flowing wa ter set tings (Drys dale, 1999;Janssen et al, 1999;Šemnièki et al, 2012), in clud ing the Háj Val ley (Gradziñski, 2010), and (2) are rec og nized in high-en ergy fos sil tufas, es pecially in warm cli mate zones .…”