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| Titel |
Seasonality, water quality trends and biological responses in four streams in the Cairngorm Mountains, Scotland |
| VerfasserIn |
C. Soulsby, R. Malcolm, C. Gibbins, C. Dilks |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 5, no. 3 ; Nr. 5, no. 3, S.433-450 |
| Datensatznummer |
250002565
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| Publikation (Nr.) |
 copernicus.org/hess-5-433-2001.pdf |
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| Zusammenfassung |
The chemical composition and invertebrate
communities found in four streams in the Cairngorms, Scotland, were monitored
between 1985-1997. Stream waters were mildly acidic (mean pH ca. 6.5), with low
alkalinity (mean acid neutralising capacity varying from 35-117 meq l-1)
and low ionic strength. Subtle differences in the chemistry of each stream were
reflected in their invertebrate faunas. Strong seasonality in
water chemistry occurred, with the most acid, low alkalinity waters observed
during the winter and early spring. This was particularly marked
during snowmelt between January and April. In contrast, summer flows were
usually groundwater dominated and characterised by higher
alkalinity and higher concentrations of most other weathering-derived solutes.
Seasonality was also clear in the invertebrate data, with Canonical
Correspondence Analysis (CCA) separating seasonal samples along axes related to
water temperature and discharge characteristics. Inter-annual
hydrological and chemical differences were marked, particularly with respect to
the winter period. Invertebrate communities found in each
of the streams also varied from year to year, with spring communities
significantly more variable (P<0.01) than other seasons (quantified
using Euclidean distance on CCA ordinations).
Hydrochemical trends over the study period were analysed using
a seasonal Kendall test, LOcally WEighted Scatterplot Smoothing (LOWESS) and
graphical techniques. These indicated that a reduction in sulphate
concentrations in stream water is occurring, consistent with declining levels
of atmospheric deposition. This may be matched by increases in pH and declining
calcium concentrations, though available evidence is
inconclusive. Other parameters, such as chloride, total organic carbon and zinc,
reveal somewhat random patterns, probably reflecting irregular
variations in climatic factors and/or atmospheric deposition. Previous studies
have shown that the stream invertebrate communities have
remained stable over this period (i.e. no significant linear trends) and show no
evidence of acid-related impoverishment. Thus, over longer
timescales invertebrates in these streams appear robust to the short-term
(seasonal and inter-annual) environmental variability and long-term
(decadal) chemical changes identified.
Keywords: hydrochemistry, hydrology, trends, macroinvertebrates, uplands,
Cairngorms, acidification |
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