Environmental heterogeneity at different scales: key factors affecting caddisfly larvae assemblages in standing waters within a lowland river catchment

Abstract

<p>We examined the importance of environmental parameters at different spatial scales influencing the occurrence of caddisfly larvae at different levels of their organization (species, faunistic metrics and functional groups) in lentic floodplain waters, in order to gain information on the ecological status and management of a small lowland river catchment. <br />At the lowest spatial level – pH, sediment grain size, insolation and the presence of aquatic macrophytes proved significant for caddisfly larvae, at higher and the highest level (including buffer zones and the catchment) – the surface areas of watercourses and the river, distance from standing waters and distance from broadleaf forests, respectively. Rheophilous hydropsychids accounted for 17% of the whole fauna of the examined water bodies. They spread from the river via water during flood in the spring. We also detected some significant correlations between functional groups of caddisfly larvae and parameters describing buffer zones and the river catchment against the sub-catchment type use. Information provided by the Caddisfly Habitat Index showed an overall good ecological status of the river-floodplain. Caddisfly larvae may be good indicators of numerous factors and processes, but they should be studied comprehensively, at different levels of organization. Our results can be useful for preservation of biodiversity and management of river valleys. We suggest: 1) maintaining the varied structure of aquatic macrophytes in water bodies, 2) securing the long-term presence of broadleaf trees in buffer zones in order to provide detritus input, varied insolation and shelter for caddisflies, 3) limiting drainage activities in the river valley in order to save varied habitats, especially temporary ones, 4) providing heterogeneous landscape in the river catchment (homogenous land use is inappropriate). </p>

Storage reservoirs beyond a lake district as secondary habitats for caddisflies (Insecta: Trichoptera) in an area of karst origin (SE Poland)

“…As the findings from this work have shown (CCAs), the process of colonisation requires the presence of small water bodies in the neighbourhood that supply an important pool of species. An identical relationship was found among the caddisflies of standing waters in the valley of a small lowland river (Buczyńska et al, 2017). This is because many lacustrine littoral species also colonise small bodies of standing water (Wallace, 1991) and migrate freely among them.…”

“…The most important were the physical and chemical parameters of the water, followed by structural factors; the least important were factors associated with buffer zones. A number of authors (Galbraith et al, 2008;Skuja and Spungis, 2010;Savić et al, 2013;Buczyńska et al, 2017) consider the parameters of water to be of greater significance than the water body's structure and/or its surroundings/ catchment area as regard the distribution of caddisfly larvae in natural waters. Even though the percentage of explained variance in each category of factors obtained by those authors and in the present work is not always high (9-40%), it is clear that these insects À as expected from their mode of life À are affected by factors acting at different spatial levels.…”

“…For a comparison, the extent of development of helophytes and the shade they provided were significant for the distribution of trichopteran larvae in a shallow dammed reservoir (Buczyńska et al, 2016). In addition, the extent of development of macrophyte cover in the water bodies of a small lowland river was one of the most important structural factors for larval caddisflies (Buczyńska et al, 2017). Weatherhead and James (2001) found positive relationships between Trichoptera and macrophyte biomass in the littoral zone of nine New Zealand lakes, and Tolonen et al (2003) discovered that Trichoptera in three lakes in Finland were significantly affected by macrophytes.…”

Water mites (Acari, Hydrachnidia) of riparian springs in a small lowland river valley: what are the key factors for species distribution?

“…In opposition to this, there are the springs from the locality of Z1, where there was only a small water bodies element, resulting from the dominant influence of flood waters. Crenobiontic fauna have a much less significant dispersal ability than rheobiontic fauna and therefore the damaged fauna is reborn much more slowly even the same environmental conditions ( Szlauer-Łukaszewska & Zawal, 2014 ; Stępień et al., 2015 ; Zawal et al, 2015 ; Zawal et al, 2016a ; Zawal et al, 2016b ; Zawal et al, 2016c ; Zawal et al, 2017 ; Dąbkowski et al., 2016 ; Płaska et al., 2016 ; Buczyński et al, 2016 ; Pakulnicka et al, 2016a ; Pakulnicka et al, 2016b ; Buczyńska et al., 2017 ; Gerecke, Martin & Gledhill, 2017 ). We did not find any rhitrobiontic species in flooded springs: these were dominated by lenitobionts and to a lesser extent by crenobionts.…”

“…Previous studies of the Krąpiel valley showed environmental factors to be acting at different levels of organization in the environment, i.e., (1) the landscape level, (2) the macrohabitat level and (3) the mesohabitat level; they all affect the species composition and the abundance of water mite assemblages ( Stryjecki et al, 2016 ; Buczyńska et al., 2017 ; Zawal et al, 2016b ; Zawal et al, 2017 ).…”