Community structure of Ephemeroptera in Siberian streams

Abstract

In recent decades, the relationships between environmental conditions and community structures of stream macroinvertebrates have been investigated in many parts of the world. However, knowledge about assemblages of mayflies and other stream macroinvertebrates in Siberia (northern Asia) and Asia is limited. In fact, the patterns in mayfly species richness and assemblage structure in relation to environmental parameters have not been previously examined in western Siberia. The aim of the present study was to examine the relationship between Ephemeroptera community structure and physical parameters along a river altitude/ longitude gradient in Siberia. The results showed that maximum species richness was at relatively low altitudes, high water temperatures, slow current velocities, medium stream widths, medium-small substrate particle size, and the presence of macrophytes. The mayfly assemblage was separated using TWINSPAN classification into eight distinct groups, which differed significantly with respect to at least one measured environmental factor. Multivariate ordination (detrended correspondence analysis) revealed that mayfly assemblages are structured by a single dominant gradient of altitude-related environmental variables; altitude and water temperature were the best predictors. Ordination further revealed that mayfly assemblages are structured by altitude-related environmental factors at high elevations, whereas in the lowlands these factors are less important.

Cross-Eurasian and altitudinal distribution of lotic mayflies – species with wider altitudinal ranges have narrower geographical distribution

“…3B). The broad altitudinal ranges imply broad ranges of the key environmental factors such as temperature and dissolved oxygen, as these factors strictly (yet non-linearly) depend on the altitude (Allan, 1995;Beketov, 2008a;Jacobsen, 2008). Such dependence is also valid for other factors such as current velocity and character of bottom substrate, but with much less accuracy, as these parameters are also influenced by local landscape characteristics.…”

“…Mean January temperatures are x18, x 18, and x20 xC respectively (extreme temperatures can reach x40 xC). Detailed description of the study area and the watercourses sampled can be found elsewhere (Beketov, 2008a).…”

“…Mayfly larvae were collected in watercourses covering the entire river continuum system from rithral to potamal zones, but excluding the crenal zone (Illies and Botosaneanu, 1963; for details see Beketov, 2008a). No mayfly larvae were found above 2200 m a.s.l.…”

“…In the palaearctic region fauna and geographical distribution of mayflies have been studied patchily, largely in Europe (Euro-limpacs Consortium, 2006), and to a smaller degree in the Eurasian Far East (Tshernova et al, 1986;Tiunova, 2007), and in the geometric centre of Eurasia in southwestern Siberia (Beketov and Kluge, 2003;Beketov, 2005aBeketov, , 2008a. Available knowledge indicates that many of the palaearctic mayflies have wide geographical distribution covering either the whole palaearctic region or half of it.…”

“…Although altitude itself is not a factor directly affecting mayflies, altitudinal ranges were used as an integrative yet approximate measure of the species' "ecological position" in a river system, as key environmental factors (e.g. temperature, oxygen, bottom substrate) depend on the altitude (Allan, 1995;Beketov, 2008a;Jacobsen, 2008; for discussion on such dependences see Discussion), and determine structure of mayfly assemblages as a single dominant gradient (Beketov, 2008a).…”