Testing for longitudinal zonation of macroinvertebrate fauna along a small upland headwater stream in two seasons

Abstract

The effect of longitudinal zonation patterns and macroinvertebrate responses to changes in habitat characteristics have been given a lot of attention. But studies of changes in macroinvertebrate assemblages along small upland undisturbed watercourses are still lacking. The aim of the study is to analyse variability in macroinvertebrate communities between two different habitats/morphological sequences -shallow (riffle/run/step/) and deeper (pool) channel-bed morphological units on the background of the environmental parameters (local relief, slope, channel confinement ratio, channel-valley walls connectivity, floodplain continuity and channel abut, channel sinuosity and predominant land cover of riparian zone) of seven valley segments (functional process zones) in two seasons of the year (spring and autumn). The longitudinaldownstream gradient research was conducted on the semi-natural upland headwater brook in the Little Carpathians (9,330 m long, average gradient 2.8%) at 15 morphological sequences (30 sampling points). Each sampling point in spring as well as in autumn was characterised by mean flow velocity, discharge, water depth, channel width, channel bottom particle size, and flow types. Selected physico-chemical variables: pH, dissolved oxygen content (DO), oxygen saturation (DO %), temperature (t) conductivity and total dissolved solids (TDS) were measured directly in the field using the multisonde measuring device. Organisms were identified into the family level. The results showed that differences in zonation of benthic invertebrates between seasons are more apparent than seasonal variability between pools and riffles. Spring samples followed the increasing gradient of total dissolved solids downstream with characteristic families for upper and lower stretch. The disruption of macroinvertebrates zonation was more evident in autumn samples with greatest effects in pools. Based on RDA, the distribution of families was driven by three significant variables in riffles and four in pools. Alike environmental factors of pool sequences in the middle and upper reaches were responsible for similarity in macroinvertebrate structure. In conclusion, the distribution pattern of benthic invertebrates of the natural part of the small headwater stream in terms of abundance of macroinvertebrate families followed the longitudinal zonation in spring, but in autumn were the local habitat conditions more important.

Macroinvertebrates at the source: flow duration and seasonality drive biodiversity and trait composition in rheocrene springs of the Western Allegheny Plateau, USA

“…Benthic macroinvertebrates make up a key organism group in headwaters, but community structure can vary across spatiotemporal (e.g., longitudinal, seasonal, flow duration) and habitat factors (Feminella 1996;Finn et al 2011). Deterministic factors such as habitat and landscape filters, stream size and network position, and seasonality (e.g., Poff 1997;Brown and Swan 2010;Finn et al 2011;Lehotský et al 2016) can serve as drivers of assemblage structure and trait composition, and thus, further studies are needed to improve our ability to characterize these relationships.…”

Seasonal modifications of longitudinal distribution patterns within a stream: Interspecific interactions in the niche overlap zones of two Ephemera mayflies

“…In many previous studies of river‐inhabiting species that tend to have a flow‐related distribution tendency, it has been important to understand the relationship between the distribution regions of species/lineages and the major primary related environmental factors (Helson et al, 2006 ; Illéšová et al, 2008 ; Lehotský et al, 2016 ). However, such studies have been conducted on the premise that differences in habitat preference and/or differences in life history between target species are determined according to their distribution ranges.…”

“…In many previous studies of river-inhabiting species that tend to have a flow-related distribution tendency, it has been important to understand the relationship between the distribution regions of species/lineages and the major primary related environmental factors (Helson et al, 2006;Illéšová et al, 2008;Lehotský et al, 2016).…”