Community Structure of Ephemeroptera in Siberian Streams

Entomological Science (2008) 11, 289–299 doi:10.1111/j.1479-8298.2008.00279.x ORIGINAL ARTICLE Community structure of Ephemeroptera in Siberian streams Mikhail A. BEKETOV UFZ – Helmholtz Centre for Environmental Research, Department of System Ecotoxicology, Leipzig, Germany 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. Key words: altitude, assemblage structure, macroinvertebrates, Siberia, species richness. INTRODUCTION vegetation (Malmqvist & Maki 1994; Wright et al. 1994), and large-scale catchment characteristics The longitudinal distribution of macroinvertebrates (Corkum 1989; Carter et al. 1996). within a river system is generally thought to be deter- In recent decades, relationships between the physico- mined by a gradient of physicochemical parameters chemical environmental characteristics of a stream and (Vannote et al. 1980). Although altitudinal/longitudinal the species richness and community structure of macro- patterns in the diversity and structure of macroinverte- invertebrates inhabiting it have been actively investi- brate communities are expected to be best explained by gated not only in Europe and North America, but also in a large set of environmental factors, many studies have many other parts of the world (King 1981; Bunn & shown that just a few environmental variables explain Davies 1992; Rundle et al. 1993). However, knowledge most of the variability in assemblage structure. These about mayflies and other stream macroinvertebrates in factors include stream size (Bronmark et al. 1984; Siberia and Asia is extremely limited. For the temperate Wright et al. 1984), velocity (Malmqvist & Maki 1994), zone in Asia, only a monograph by Levanidova (1982) substrate (Minshall 1984), temperature (Jacobsen describes mayfly assemblage composition in relation to et al. 1997; Minshall & Robinson 1998), in-stream environmental parameters. However, this study is purely descriptive and does not analyze the general relationships between environmental factors and biological Correspondence: Mikhail A. Beketov, UFZ – Helmholtz Centre for Environmental Research, Department of System communities. Mayflies (Ephemeroptera) are an impor- Ecotoxicology, Permoserstrasse 15, D-04318 Leipzig, tant and abundant component of stream macro- Germany. Email: [email protected] invertebrate communities (Ward 1992). The spatial Received 12 December 2007; accepted 23 January 2008. distribution of these organisms is known to be © 2008 The Entomological Society of Japan M. A. Beketov dependent on the natural altitude/longitude environ- characterized by mountainous relief. These two regions mental gradient (Dodds & Hisaw 1925; Kamler 1967; are western components of the great South-Siberian Brodsky 1980; Levanidova 1982; Ward 1986) as well Mountain System stretching from the Altai Mountains as influenced by anthropogenic factors or stressors in the southwest and the Putorana Mountains in the (Beketov 2004). northwest to the Pacific Ocean in the east. The majority Although the mayfly fauna has been recently investi- of the mountains are below 2000 m a.s.l. (maximum gated in western Siberia (Beketov & Kluge 2003; elevation is 4506 m a.s.l, Belukha Mountain). Mean Beketov 2005, 2007; Beketov & Godunko 2005), the January temperatures are -18°C and -20°C, mean June patterns of species richness and assemblage structure temperatures are 12°C and 16°C, and mean precipita- in relation to environmental parameters have not tion values are 800 mm and 1600 mm per year in the been examined. The aim of the present study was to Altai Republic and Khakassia, respectively (Davitaya investigate patterns in Ephemeroptera species richness 1960). Taiga is the predominant vegetation, being and assemblage structure and test their correlation to replaced by alpine meadows and alpine tundra at eleva- physical parameters associated with a river altitudinal/ tions higher than 2000 m a.s.l. Watercourses longitudinal environmental gradient. Measured param- are predominantly fed by rain/snow (Blazhenov & eters were altitude, stream width, temperature, current Khudyakova 2000). velocity, bottom substrate and presence/absence of macrophytes. The samples used in the present analysis Sampling and data processing were collected exclusively in pristine, uncontaminated In total, material from 1976 samples collected at 46 sites streams to exclude anthropogenic effects. was used. Mayfly larvae were collected using D-frame nets (500 mm mesh) in pristine streams (width 0.5– MATERIALS AND METHODS 185 m). Samples were taken from all major habitat types present in a stream (including stones, pebbles, Study area submerged macrophytes and fine sediments). In large The samples used in the present analysis were collected watercourses, only the littoral section was sampled to during 2002–2005 in three regions of southwestern a depth of 1 m. Collected macroinvertebrates were Siberia: Novosibirsk Province, Altai Republic, and preserved in 95% ethanol and identified in the labora- Khakassia (Fig. 1). Novosibirsk Province is in the south- tory. Sampling methods were not fully uniform for all eastern corner of the West Siberia Plain and is mainly samples. In particular, sampling area varied between characterized by a flat relief (Fig. 1a). In the southeast of 0.125 and 0.25 m2, and highly abundant species this province are found the low mountains of Salairskii were not quantified in some samples. Hence a species Kryazh (up to 502 m a.s.l.), drained by the Berd River presence/absence table was created for the present basin. All study sites in Novosibirsk Province were in the analysis and the abundance of each species was not Ob River basin, except one site in the Om River basin considered in the analysis. Large plain rivers (e.g. the Ob far to the west (Fig. 1a). The climate of the region is River) were not included in the analysis, as they were moist continental, mid-latitude with cold winters (mean contaminated and not relevant to the present study. January temperature is -18°C, extreme temperatures Slow-flowing plain rivers, which are typical of swampy can reach -40°C) and relatively warm summers (mean territories of the Western Siberian Plain, were also July temperature is 20°C). Precipitation is 500–800 mm excluded. per year (Davitaya 1960). During the long winter most Taxonomy used here is based on Kluge (1997). Thus, water bodies are covered with ice (from November to the genus Baetis is considered “broadly” according to April). Study sites in the province are mostly in the revisions made by Novikova and Kluge (1987) and forest–steppe zone. In the south, patches of true steppes Novikova (1987), with Acentrella, Baetiella, Labioba- are a significant part of the landscape, whereas birch/ etis Nigrobaetis, and Pseudocloeon considered as sub- aspen forests of the sub-taiga type with a minor com- genera. The genus Ecdyonurus includes Afghanurus and ponent of spruce occur in the north. Watercourses Afronurus as subgenera. are fed by a mixture of groundwater, rain and snow (Krivonogov 1969; Blazhenov & Khudyakova Environmental parameters 2000). The following environmental characteristics were con- In contrast to Novosibirsk Province, the Altai Repub- sidered in this study: altitude, mean summer water tem- lic (Fig. 1b) and Khakassia (Fig. 1c) are predominantly perature, current velocity, stream width, and dominant 290 Entomological Science (2008) 11, 289–299 © 2008 The Entomological Society of Japan Ephemeroptera in Siberian streams Figure 1 Study area: (a) Novosibirsk Province, (b) Altai Republic, and (c) Khakassia. (᭹), Sampling points; (ᮀ), cities. substrate particle size. Absolute altitude was measured to seven different size classes according to the method of using a geographic positioning system (GPS) device Hering et al. (2003) and a “semi-continuous” variable (e-Trex; Garmin, Olathe, KS, USA) or using available called dominant substrate mean particle size was used in maps. Water temperature was measured using a mercu- the analysis. Surface current velocity was assessed by rial thermometer. Mean summer temperature for each timing a bobber (n = 3) over 5 m of stream. Last,

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