Longitudinal zonation of larval Hydropsyche (Trichoptera: Hydropsychidae): abiotic environmental factors and biotic interactions behind the downstream sequence of Central European species

Abstract

The aim of this review is to summarize the literature knowledge about how abiotic environmental factors and biotic interactions affect the sequentially overlapping longitudinal distribution of Central European species of the net-spinning freshwater caddisfly larvae of the genus Hydropsyche (Trichoptera: Hydropsychidae). In this relation, several physical and chemical parameters of water are discussed, as well as different species-specific traits, behavioural aspects and the interaction of coexisting species. Longitudinal gradients of river networks, especially annual temperature range, flow velocity and the particle size of suspended food material play a crucial role in forming the downstream succession of characteristic species, while increased levels of organic pollution, nutrients, salinity and heavy metals facilitates the presence of more tolerant ones. Several species-specific traits, such as respiration range, net-building frequency, head capsule size or optimal net-building velocity correlate with the position of a given species in the sequence. Coexistence of species with similar ecological demands in the overlapping zones of distribution is facilitated by differences in feeding and net-building habits, microhabitat preferences and staggering life cycles, but complicated at the same time by means of inter- and intraspecific territorial behaviour, such as fighting for the ownership of larval retreats or the practice of stridulation.

Water quality shapes the community structure of zoobenthos in rivers but only has a minor effect on the fatty acid composition of zoobenthos and salmonids

“…The zoobenthos communities were generally unique in each river, and the differences were mostly driven by differences in EPT‐taxa abundances. Species of these taxa have different tolerances for multiple environmental conditions (Ficsor & Csabai, 2021; Smith et al, 2007), and they are, therefore, used as the key indicators in EU WFD‐based ecological status classification.…”

“…In addition to tOM loading, characteristics of riverbed substratum (bottom material) explained zoobenthos community structure among the studied rivers. Diverse riverbed substrata support zoobenthos diversity (Huttunen et al, 2022); particularly many hydropsychids prefer specific substrata (Ficsor & Csabai, 2021). Aquatic macrophytes offer suitable microhabitats for several zoobenthos taxa, and macrophyte coverage can greatly influence the zoobenthos community structure (Huttunen et al, 2017).…”

“…The addition of gravel and boulders could benefit different EPT‐taxa by providing them with new microhabitats. Improvement of water quality, especially the rising pH, has also been reported as beneficial for hydropsychids (Ficsor & Csabai, 2021). Sasaki et al (2005) found that an increased concentration of nutrients and organic matter might also be beneficial for hydropsychids.…”

“…Cashman et al (2016) found high autochthonous signatures from the FA composition of Trichoptera, but some evidence suggests that site characteristics might also affect the FA composition of Hydropsyche (Cashman et al, 2016). Even though many hydropsychids are classified as filter‐feeders (Cummins, 1973), there is evidence that they also practice selective feeding and omnivory (Basaguren et al, 2002; Ficsor & Csabai, 2021; Hellmann et al, 2013; Torres‐Ruiz & Wehr, 2020). Previous study has documented high levels of 12:0 and 18:1ω9 and low levels of 16:1ω7 and EPA in Hydropsychidae, which may indicate a high contribution of allochthonous detritus in their diet (Descroix et al, 2010).…”

Ecological indicators for qualitative assessment of Ojarud River: A case study

“…The underlining reasons for the popularity of the macroinvertebrate‐based bioassessment of river health could be its continuous monitoring of water quality in contrast to one‐time sampling for chemical experiments, the abundance of taxa, their sedentary lifestyle and long lifetime, facial sampling and identification, presence in all areas of the river (crenal, rhithral, and potamal zones), distinct responses of each taxon to physicochemical pollutions, for example, acidification, eutrophication, and organic enrichment, and anthropogenic activities for example, river regulation, impoundment, and canalization, as well as playing a key role in effective river food web along with river continuum (Alba‐Tercedor, 2006 ; Ficsór & Csabai, 2021 ; Sumudumali & Jayawardana, 2021 ).…”