INTRODUCTION
Road run-off includes |
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Treatment is bySo:- |
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motorway run-off might affect stream biology including
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AIMto investigate impact of motorway drainage on periphyton
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METHODS
- Motorway in Northern England sampled April/March
- 7 streams (4-10 m width)
- 4 rocks from shallow stony riffles
- Sampled via 10 mm x 10 mm hole in a celluloid template
- Periphyton (‘auchwuss’)
- cropped with forceps
- scraped with a scalpel
- removed by irrigation with a pipette
- uni-cells counted
- filamentous relative abundance estimated
- identified to species level at a x400 with light microscope
Intensive survey
- more intensive survey undertaken at one site (Sparishaw)
- Upstream (US) and downstream (DS) sites divided into 3 major zones
- 4 replicate samples taken in each zone
Factors under consideration for general survey
- difference between streams
- US-DS location
- variation between replicates
Factors under consideration for intensive survey
- US-DS location,
- variation between zones
- variation between replicates
RESULTS
No. of species | General …. 62 Intensive ….. 41 |
General river survey – by species | ||||||
Taxon |
Factor
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Interactions
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River (A)
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. US/DS (B)
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Replicates (C)
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A x B
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B x C
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A x C
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Acnanthes sp. |
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Cocconeis pediculus |
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Fragilaria capucina |
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Gomphonema constrictum |
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Meridion sp. |
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Navicula cryptocephala |
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Nitzschia dissipata |
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Pinnularia sp. |
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Rhoicosphenia sp. |
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Intensive survey of Sparishaw stream – by species | ||||||
Taxon |
Factor
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Interactions
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US/DS(A)
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Zone (B)
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Replicates (C)
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A x B
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B x C
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A x C.
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Acnanthes sp. |
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Amphora sp. |
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Cocconeis placentula |
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Cymbella sp. |
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Meridion sp. |
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Navicula cryptocephala |
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Nitzschia palaea |
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Pinnularia sp. |
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Stauroneis sp. |
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Surirella sp. |
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General river survey – Summary | ||||||
Taxon |
Factor
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Interactions
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River (A)
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US/DS (B)
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Replicates(C)
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A x B
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B x C
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A x C
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Species |
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Individuals |
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Relative abundance |
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Diversity (Shannon Wiener) |
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Intensive survey of Sparishaw stream – Summary | ||||||
Taxon |
Factor
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Interactions
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US/DS(A)
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Zone (B)
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Replicates (C)
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A x B
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B x C
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A x C
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Species |
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Individuals |
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Relative abundance |
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Diversity (Shannon Wiener) |
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So, analysis of variance shows
- no variation between replicates – expected
- differences between rivers – expected
- no differences between zones – expected
- US/DS differences
- few interactions (expected because of 1 and 3)
DISCUSSION
Stresses may be due to
- physical non-conformity where the river is culverted under the motorway.
- motorway pollution from
- petrol – Pb and toxic light oil fractions
- tyres – rubber, soot, heavy metal oxides, Cr, Cu, Pb and Zn
- engine oil – Cr, Ni, Cu and organic phosphates
- ice, snow and de-icing agents
- de-icing salt (a pulse of 2165 mg/l Cl can cause drift of invertebrates)
- chemicals accumulated in the snow pack at the side of the road.
One site showed lower diversity DS of the motorway due to both
- a farm US of the motorway
- erosion DS of the motorway
Anova shows differences US and DS but are conditions WORSE downstream of the motorway ?
Look at graphs of the data per square mm
- number of species
- number of non filamentous algal cells
- relative abundance of filaamentous algae
- diversity (Shannon Wiener)
Note …
- At almost all sites there was a more diverse epiphyton DS of the motorway
- Nutrient poor water – eutrophication ?
- If so, there should be more downstream biomass of
- macroinvertebrates
- fish
- But DS of the motorway there are
- fewer macroinvertebrates
- more fish
CONCLUSION
- Little evidence of a bad chemical impact of the motorway when surveyed in Spring.
- There appears to be an effect of the
- So, use appropriate engineering techniques