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Communication at the NABS Annual meeting, Keystone, 2000
(426) CLOGGING EFFECTS OF SEDIMENT ON ANIMAL DISTRIBUTION IN THE
HYPORHEIC ZONE OF A GRAVELLY MOUNTAIN BROOK.
E.B. Meidl. Institute of Ecology, work. assoc. Limnology, Friedrich-Schiller-University, Winzerlaer Str. 10, 07745 Jena, Germany
The sediment structure and the macroinvertebrates of the
hyporheic zone of a gravelly brook in the Thuringian Slate
Mountains are studied at four sampling sites from sediment surface
to 60cm depth during autumn and winter period. Two of the sites
are characterized with high porosity of their bedsediment, and two
of them with tendencies to clogged sediment structure. By using
freeze-core technique with in situ electro-positioning and cutting
the cores in slices of 10cm thickness a quantitative approach is
feasible for each bedsediment layer. Oxygen is present throughout
the bedsediment.
Temperature data-loggers have been installed from surface to a
depth of 40cm at each site. The temperature peaks get more and
more polished with depth. After disturbance with an outwash of fine
grain it needs nearly two month to fill up the pores.
Within sedimentological analysis grain-size and total organic
carbon (TOC) are detected. The increase of fine grained particles is
not correlated with the TOC content, but it is followed by higher
abundance of sediment feeders like Oligochaeta and Chironomidae
larvae. Other members of the macroinvertebrates such as insects
decrease very much in the deeper sediment layers, because of
the clogging-effects. In contrast, Acari seems not to be influenced.
Presented at 1:00 PM on Wednesday, May 31, 2000 in Hyporheic Zone
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