Substrate-specific macroinvertebrate diversity patterns following stream restoration

Abstract

We examined the effects of stream restoration efforts that re-established multiple-channel sections in otherwise single-channel streams on aquatic habitat diversity and macroinvertebrate assemblages. At seven pairs of sites (single-vs. multiple-channel) we analysed the diversity of aquatic habitat parameters at various spatial scales (e.g. shore length, channel features, substrate diversity, flow variability). We also sampled macroinvertebrates in all available substrates individually and compared alpha-and beta-diversity and nestedness patterns on substrates between singleand multiple-channel sections. Multiple-channel sections showed a considerably more diverse hydromorphology. Taxa number, abundance, and evenness of macroinvertebrate assemblages did not differ significantly. Ten Coleoptera and seven Trichoptera taxa were present exclusively in multiple-channel sections on loam, sand, living parts of terrestrial plants (LPTP), coarse particulate organic matter (CPOM) or large wood. Non-metric Multidimensional Scaling showed that macroinvertebrate assemblages were substratespecific rather than section-specific. Nestedness did not differ for samples from single-and multiplechannel sections, nor for individual substrates from different sections. We did not observe differences in alpha-diversity from substrates at single-and multiple-channel sections. However, different substrates host different assemblages and the increased substrate diversity in multiple-channel sections might result in higher beta-diversity in these sections. Our results indicate that stream restoration projects aimed at redeveloping near-natural macroinvertebrate diversity should focus on generating several long multiplechannel stretches with large areas of high quality habitats (e.g. large wood), creating stepping stone habitats for re-colonisation, and should allow sufficient time for new assemblages to establish.

Evaluating macroinvertebrate community shifts in the confluence of freestone and limestone streams

“…This is commonly due to increases in depth, velocity, and substrate size as the distance from the bank increases (Bournaud et al, 1998;Jowett, 2003); however, we found no difference in depth and velocity between experimental sites and minimal changes in substrate. Differences in substrate composition (higher silt in sites near the bank) are also consistent with substrate commonly found in limestone streams (Glazier and Gooch, 1987;Harrison et al, 2004;Jähnig and Lorenz, 2008) and could have been a result of the sediment input that commonly occurs at the confluence of two streams (Rice et al, 2001(Rice et al, , 2006. Additionally, as substrate had a fairly minimal impact on community structure compared to chemical values (Tab.…”

“…This may be due to a number of characteristics that differ between the streams. Limestone streams often have more sand and silt based substrates, which can reduce diversity by diminishing substrate stability and decreasing the availability of colonisable habitat, refugia, and food availability (Glazier and Gooch, 1987;Harrison et al, 2004;Jähnig and Lorenz, 2008;Barnes et al, 2013). Additionally, the high alkalinity and conductivity inherent to limestone streams can decrease diversity, although these effects can be difficult to separate from high discharge and velocity (Neff and Jackson, 2011), which also can reduce diversity by diminishing colonisation ability (Townsend et al, 1997;Barquín and Death, 2004).…”

Diversity of macrobenthos in lowland streams: ecological determinants and taxonomic specificity

“…A great influence of sampling methods on the composition of qualitative collection was presented in numerous studies involved in various habitats (e.g., Lenat 1988;Koperski 2003). Differences in taxonomic composition are also dependent on micro-habitat divergence (Ormerod 1988;Jähnig & Lorenz 2008;) -the occurrence of common taxa frequently differed between types of bottomsubstrate or along the stream cross-section.…”

“…Differences in taxonomic diversity of stream fauna due to environmental patterns have been documented in numerous studies, e.g., as the effect of moderate pollution (Barbour et al 1996, Koperski 2005, oxygen depletion (Jacobsen 2008), climatic differences (Heino 2002), type of bottom substrate (Jähnig et al 2008), type of land-use in catchment area (Utz et al 2009), flow velocity (Strzelec & Królczyk 2004), organic matter accumulation and substratum characteristics (Graça et al 2004). In an exhaustive study by Ribera (2007) the diversity of lotic invertebrates is suggested to be determined by historical, geological and climatic constraints of habitats.…”

“…The diversity of Odonata seems to be strongly correlated with the local climatic specifics (Eversham & Cooper 1998); furthermore, it is more sensitive than the diversity of other taxonomic groups to the structure of riparian vegetation (Smith et al 2007). Differences between the diversities of higher taxa as a result of divergence in stream bottom have been presented, among others, by Benke et al (1984) and Jähnig et al (2008). The richness of four insect orders studied by Rosemond et al (1992) was affected in different ways by chemical parameters of stream waters.…”