Rotifers of the Lone Oak in the Ashdown Forest | Rotiferalia

ROTIFERS of the Lone Oak

  • Lone Oak stream in the Ashdown Forest
  • Biomass distribution of benthic rotifers and meiofauna
  • Leptothrix filaments in the streambed
  • Mean invertebrate biomass at the streambed surface and the hyporheic interstitial
  • PlaceThe Lone Oak
  • Coordinates51° 04' 22" N, 0° 06' 14"E
  • Type
    • Gravel stream
    • median grain-size: 8.2 mm
    • pH: acidic

This fishless, acidic stream has a dense riparian vegetation dominated by oak and beech, that shades the stream and provides a source of allochthonous leaf litter. The stream is spring-fed and oligotrophic, and is characterized by a median grain-size of 8.2 mm (Q75= 34.8 mm; Q25= 2.4 mm) in the upper 20 cm of the streambed. In summer, the stream has an orange colour as a result of deposits of the iron bacteria Leptothrix ochracea (see filaments in image).

We identified 161 different invertebrate species, including 15 protozoan and 40 rotifer species, which occur at the streambed surface of the Lone Oak. In this stream, rotifers do not contribute substancially to the overall biomass, but total meiofauna biomass occasionally equalled that of all macroinvertebrates1,2. We found that more than half of total production was accounted for by the permanent and temporary meiofauna.

In the Lone Oak, invertebrate densites were high in samples collected from below the streambed surface, with a peak density at 15 cm sediment depth. These results suggest that invertebrate density could be grossly underestimated by a factor of between 1.6 and 4.7 times, if counts are only based on streambed surface surveys. Moreover, total invertebrate biomass, including all depth layers, may be underestimated by a factor of between 1.2 and 3.5, if based purely on surface samples3.

1. Stead, T.K., Schmid-Araya, J.M. & Hildrew, A.G. 2005. Limnol. Oceanogr. 50, 398 ( download this publication ).
2. Stead, T.K. et al. 2005. J. Anim. Ecol. 74, 475 ( download this publication).
3. Stead, T.K. et al. 2004. Arch. Hydrobiol. 160, 171 ( read the abstract).

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