Spatial and temporal patterns in the macroinvertebrate communities in streams
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My research looked for evidence of community persistence in two suites of
sites. Twenty-nine stream sites were in the Ashdown Forest of southern England and
twelve streams which form part of the United Kingdom Acid Waters Monitoring
Network. Benthic macroinvertebrates were collected using different methods and the
species and physico-chemical data analysed. The Ashdown sites were sampled in 1989
and 1990, and the data collected was compared with previous studies and an analysis
made of community persistence over a period of thirteen years. Persistence was assessed
using measures of similarity and rank correlation coefficients. The data showed that
several physico-chemical factors, in particular stream pH, were related to the structure of
the benthic communities. Summer temperatures and stream discharge were also
significantly associated with the patterns obtained. Using multivariate methods,
TWINSPAN, DECORANA and CANOCO, spatial patterns were discerned. Comparisons
of the two previous surveys and my own data showed that sites with low pH, low summer
temperatures and low discharge had consistent spatial patterns.
The United Kingdom Acid Waters Network stream sites were originally chosen
for their susceptibility to acidification and are located in different geological and
geographical parts of the UK. The same persistence measures were used as for the
Ashdown data and, although there was greater variability, similar underlying patterns
were found. Using the same methods the Ashdown and UKAWMN sites were then
analysed together.
Authors
Edmonds-Brown, Veronica RobertaCollections
- Theses [4099]