ROTIFERS of the Seebach

• PlaceOberer Seebach
• Coordinates45° 51'N, 5° 04'E
• Type
  • Gravel stream
  • median grain-size: 23.1 mm
  • pH: circumneutral

This calcareous gravel stream has a heterogeneous grain-size distribution, high porosity, strong variations in water through-flow and available biofilm.

Over more than 20 years, this stream was taxonomically assessed, resulting in a compilation of 575 invertebrate and fish species inhabiting both the streambed surface and subsurface of the experimental stream reach 'Ritrodat'. We demonstrated that an inverse proportionality between species density and body-size was a consistent feature among 448 and 260 species in the Seebach and the Afon Mynach, respectively1,2.

We found 105 rotifer species of which 68 and 37 species were monogononts and bdelloids, respectively3,4. Temporal density variations of monogononts at the streambed surface revealed significant maxima in autumn and summer. In contrast, bdelloids displayed no distinct density peaks over time, but, depending on season, their abundances differed significantly between pool and riffle sites.

In the hyporheic zone (subsurface 10 - 40 cm), monogonont densities varied seasonally between sediment depths. In contrast, bdelloid densities varied site-specifically among different sediment depths. These pool/riffle-specific depth variations were similar across the year3.

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