influence of low flows on diversity and recovery
TRANSCRIPT
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Influence of low flows on diversity and recovery of macrozoobenthos communities as one of the components of ecological status assessment
according to the Framework Directive. Jan Špaček and Pavel Hájek
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• At the Magdeburg Seminar in Teplice we presented the problem of drying of small and medium streams focused on ecological status assessment.
• In years 2014‐2017 we met extremely low flow rates even at the large rivers.
• We focused on macrozoobenthos community changes.
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Locality, methodology
• Elbe River – Decin• Elbe River – Valy
• Summer samples, low influence• Macrozoobentos• 3 minutes multihabitat sample • Years 2012, 2014 ‐ 2017
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Elbe River ‐ Decin
• Partly natural watercourse• Stony and gravel shores• About 100 m widht (normal flowrates)
• About 70 m widht (low flowrates)
• Right site sample
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Elbe River ‐ Valy
• Technically modifiedwatercourse
• Riprap and pavement shores• About 60 m widht (all flow rates)• Right site sample• influenced by the drainage of the weir in Prelouc
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Physico ‐ chemical factors
• Temperature increase• pH and conductivity changes • Oxygen regime changes • Increasing nutrient and pollutant concentrations • Precipitation of metals on the surface of the substrate and organisms • The objective reduction of living space and number of microhabitats • Reduction of flow velocity • Siltation
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Hydromorphological factors
• Flow size • Geological subsoil • Extent, scope and type of anthropic adaptations • Landscape type
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Ecological factors
• Direct die‐off organisms • Predation increasing • Greater parasite development and easier transmission of diseases • Escape reactions• Rising of invasion species populations
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Elbe River ‐ Decin
0
2000
4000
6000
8000
10000
12000
Děčín Děčín Děčín Děčín Děčín
2012 2014 2015 2016 2017
Non‐native species
Native species
Abundance
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Elbe River ‐ Decin
3 4 46
9
38
2825 20
24
0
5
10
15
20
25
30
35
40
45
Děčín Děčín Děčín Děčín Děčín
2012 2014 2015 2016 2017
Native species
Non‐native species
Number of species
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Elbe River ‐ Valy
0
100
200
300
400
500
600
700
800
900
Valy Valy Valy Valy Valy
2012 2014 2015 2016 2017
Non‐native species
Native species
Abundance
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Elbe River ‐ Valy
2 3 3 39
25 2317
29
47
0
10
20
30
40
50
60
Valy Valy Valy Valy Valy
2012 2014 2015 2016 2017
Native species
Non‐native species
Number of species
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Neogobius melanostomus – round goby
Elbe River ‐ Decin
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Kolín
Obříství
Veletov
Týnec n.L.
Dikerogammarus villosus
Dikerogammarushaemobaphes
Corophium curvispinum
Corophium robustum
Jaera istri
Killer shrimp
Demon shrimp
Caspial mud shrimpDonau assel
Corbicula fluminea
Přelouč
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Thank you for your attention!