Spatial patterns in macroinvertebrate assemblages in surface-flowing waters of a glacially-influenced floodplain

Abstract

We examined the spatial structure of macroinvertebrate assemblages in surface-flowing waters of a glacially-influenced floodplain. The floodplain main-channel responded longitudinally to changes in hydrology with evident coarse-scale zones of upwelling and downwelling; the lower floodplain main channel fell dry in late winter. Physico-chemical attributes differed among tributaries and the main channel. The main channel had lower values of conductivity, alkalinity and nitrate-N than tributaries, with right-side (east-facing) tributaries having the highest values. Left-side (west-facing) tributaries flowing over an exposed rock-face had warmer water temperatures than the main channel and right-side tributaries. The biomass of benthic organic matter and periphyton was highest in rightside tributaries, followed by main channel sites then leftside tributaries. Similarly, macroinvertebrate density and richness were higher in right-side tributaries, intermediate in main channel sites, and lowest in left-side tributaries. Macroinvertebrate assemblages clearly differed between main channel sites, right-side tributaries, and left side tributaries based on an NMDS analysis. Minor differences were observed among main channel sites, although most upstream sites showed some structural differences from downstream sites. Ephemeropterans and plecopterans were most common in main channel sites and right-side tributaries, whereas chironomids and trichopterans also were common in right-side tributaries. Although the main channel changed longitudinally in physico-chemical characteristics, no real patterns of zonation were evident in macroinvertebrate assemblages. Coarse spatial patterns in macroinvertebrate assemblages in the floodplain were reflected in the physico-chemical differences between the main channel and tributaries, and between left-side and right-side tributaries. We conclude that coarse-scale floodplain properties enhance the overall diversity of lotic macroinvertebrates. Consequently, floodplain alterations that reduce surface water heterogeneity/connectivity limits the potential macroinvertebrate diversity of floodplains.

How effective is river restoration in re-establishing groundwater–surface water interactions? – A case study

“…The slightly elevated surface water temperatures in the main channel were caused by the channel being fully exposed to the sunlight throughout the experiment, while the drainage ditch was shaded in the afternoon. Robinson and Doering (2013) observed a similar pattern of groundwater upwelling in the investigated section of the Urbach's main channel and groundwater-fed tributaries on the eastern side of the stream. Presumably groundwater upwelling occurred uniformly and on a large scale, as no localized regions of groundwater temperatures were observed in the main channel or the drainage ditch.…”

Analysis of the temperature dynamics of a proglacial river using time-lapse thermal imaging and energy balance modeling

“…Mean annual air temperature is 6.4°C (average for 1960-2000). For further details of the study site refer to Doering et al (2012) and Robinson and Doering (2013). The study was conducted in August 2011 when discharge was low; no storms occurred during the study period.…”

The habitat type and trophic state determine benthic macroinvertebrate communities in lowland shallow lakes of China

“…Generally, macrophytes can provide habitats and foods for aquatic animals, which can increase spatial heterogeneity and allow more species of various ecological niches to coexist in a macrophytedominated lake (Padial et al, 2009;Bazzanti et al, 2010;Robinson and Doering, 2013). In addition, macrophytes provide more surface area for attachment by periphytons, which are a major component in the diet of macroinvertebrates (Jones et al, 1999;Cai et al, 2011).…”