Ecological Implications of Road Construction in an Alum Shale Bedrock Area

Transcription

1 Ecological Implications of Road Construction in an Alum Shale Bedrock Area A State Highway (Rv4) Case Study Joachim Gustav Engelstad Master of Science in Ecology NMBU, INA

2 Introduction Construction and use of roads and tunnels affect surrounding aquatic ecosystems Synthetic and natural contaminants (TSS, ph, metals, petroleum, N compounds etc) Treated and untreated runoff NPRA Rv4 Hadeland Alum shale bedrock (Fe, Al, U) EU WFD and NORWAT Benthic macroinvertebrates Bioindicators Bioaccumulation

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5 Objectives 1) Which environmental variables are the most important drivers for the observed variation in macroinvertebrate assemblages? 2) Are levels of mayfly metal concentrations different in impacted areas compared to reference areas? 1) Has this affected benthic macroinvertebrate communities?

6 Predictors Effects Station Vigga upstream, Vøien, School, Vigga downstream, Nordtangen, Vigga upstream 2 Season Spring 13, Autumn 13, Spring 15, Autumn 15 Year 2013, 2015 Treatment Reference (control), impact (impacted areas) Covariates Aluminium (Al) Iron (Fe) Cadmium (Cd) Thorium (Th) Uranium (U) ph Conductivity Temp C PC1 PC2 ASPT Key nuclide associated with alum/black shale bedrock Key nuclide associated with alum/black shale bedrock Key nuclide associated with alum/black shale bedrock Key nuclide associated with alum/black shale bedrock Key nuclide associated with alum/black shale bedrock Important in mobilisation of metals from bedrock Represents first metal gradient for use in constrained ordination Represents second metal gradient for use in constrained ordination Average Score Per Taxon (based on the BMWP Index)

7 Results 1800 Other Number of individuals Coleoptera (beetles) Oligochaeta (worms) Chironomidae (non-biting midges) Trichoptera (caddisflies) Plecoptera (stoneflies) Ephemeroptera (mayflies)

8 Group n Total prop (%) Species or family n Relative prop (%) Total prop (%) Emphemeroptera Baetis rhodani Alainites muticus Baetis nigris Plecoptera Taeniopteryx nebulosa Protonemura meyeri Amphinemura standfussi Trichoptera Rhyacophila nubila (Limnephilidae indet) Silo pallipes Chaetopteryx villosa Coleoptera Elmidae Hydraenidae Others Simuliidae Psychodidae Pediciidae (Dicranota spp) Total Chironomidae Oligochaeta Total

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10 Explained variation PC axis 1: 16.82% PC axis 2: 15.59% Adjusted explained variation across all axes: 40.9%. First axis and all axes are equally significant (p = 0.002).

11 Shannon-Wiener Diversity Index PC axis 1: 21.59% PC axis 2: 6.72% Adjusted explained variation: 19.3%. First axis and all axes equally significant (p = 0.002).

12 ASPT Index Scores

13 Metals PC axis 1: PC axis 2: 7.29% PC axis 1: 67.53% PC axis 2: 5.52% Adjusted explained var: 72.9%. PC axis 1: 25.18% PC axis 2: 14.25% Adjusted explained var: 35%

14 Most important predictors

15 PC axis 1: 34.66% PC axis 2: 15.49% Adjusted explained variation: 44.5% First axis and all axes are equally significant (p = 0.002).

16 ASPT vs metal concentrations

17 Discussion Response of organism dependent on stressor Environmental and animal tissue metal concentrations = positively correlated (studies show) Metal (and organic) pollution = proliferation in tolerant species (i.e. chironomids) Long-term = tolerant communities form Metals and radionuclides Similar studies show increased metals in watercourses near construction sites Reduced ph = significant release of metals May persist and never recover, i.e. E18 Grimstad-Kristiansand & Lake Lomtjenn May interfere with physiological functions in fish Limited knowledge - direct effects more known than sub-lethal effects Generally reduced fitness and survival in organism Study: gradual exposure to metals = reduced tolerance to UV-B Perhaps sampled too late for spring emergence theory!

18 Conclusion Rv4 project has caused negative ecological changes to benthic macroinvertebrate communities In accordance with the findings of various other studies Impacted areas: Lower taxa diversity More tolerant than sensitive taxa (i.e.. chironomids) Lower ASPT index scores Increased mayfly metal concentrations (Al, Cd, Fe, Th, U strongly correlated) EPTs favoured 2013, chironomids 2015 (year most important predictor) Seasonal variability most important, treatment and metals second and third, respectively Spring similar to impact, autumn similar to reference (emergence? spring runoff?) ASPT scores significantly negatively correlated with mayfly metal concentrations

19 Thank you for your attention!