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| Titel |
Surface flow types, near-bed hydraulics and the distribution of stream macroinvertebrates |
| VerfasserIn |
M. A. Reid, M. C. Thoms |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 5, no. 4 ; Nr. 5, no. 4 (2008-07-28), S.1043-1055 |
| Datensatznummer |
250002677
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| Publikation (Nr.) |
 copernicus.org/bg-5-1043-2008.pdf |
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| Zusammenfassung |
Spatial variation in hydraulic conditions in streams often results in
distinct water surface patterns, or surface flow types. Visual assessments
of the distribution of surface flow types have been used to provide rapid
assessment of the habitat heterogeneity. The efficacy of this approach is
predicated on the notion that surface flow types consistently represent a
distinct suite of hydraulic conditions with biological relevance. This study
tested this notion, asking three specific questions. First, do surface flow
types provide a characterisation of physical habitat that is relevant to
macroinvertebrates? Second, how well do near-bed hydraulic conditions
explain macroinvertebrate distributions? Third, what components of near-bed
hydraulic conditions exert the strongest influence on macroinvertebrate
distributions?
Results show that hydraulic conditions (incorporating direct measurements of
near-bed velocity and turbulence in three dimensions) and substratum
character (incorporating estimates of particle size distribution, and
biofilm and macrophyte cover) within each surface flow type were largely
distinct and that macroinvertebrate assemblages differed across flow types
in taxon richness and assemblage composition, thus supporting the notion
that rapid assessments of surface flow type distributions provide
biologically relevant information.
Macroinvertebrate assemblages were most strongly correlated with water
depth, size of a flow type patch, near-bed velocity in the downstream
direction, turbulence in the transverse direction, % pebble, % sand,
% silt and clay and macrophyte cover. This study suggests that surface
flow type mapping provides an assessment of physical habitat that is
relevant to macroinvertebrates. The strong relationship detected between
macroinvertebrate assemblages and transverse turbulence also highlights the
value of directly measuring near-bed hydraulics. Further investigations are
required to test the mechanisms underlying this relationship. |
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