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Environmental Assessment and Sustainability CIV913

Environmental Assessment and Sustainability CIV913. BIOLOGICAL ASSESSMENT of River Water Quality. Assessing the biological quality of fresh waters : Wright, J. F., Water Pollution Biology - Abel PD Water Quality Monitoring - Bartram J & Ballance R Freshwater Ecology - Jeffries M & Mills D

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Environmental Assessment and Sustainability CIV913

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  1. Environmental Assessment and Sustainability CIV913 BIOLOGICAL ASSESSMENT of River Water Quality Assessing the biological quality of fresh waters :Wright, J. F., Water Pollution Biology - Abel PD Water Quality Monitoring - Bartram J & Ballance R Freshwater Ecology - Jeffries M & Mills D Ecology of Freshwaters - Moss B

  2. BIOLOGICAL ASSESSMENT Biological Methods • Macroinvertebrate community status • Macroinvertebrates - specific taxa • Macrophyte community assessment • Diatom community status • Sewage fungus • Bioaccumulation • Moss bags • In-situ and ex-situ Bioassays • combinations of the above

  3. BIOLOGICAL ASSESSMENT • INDICATOR ORGANISMS Those which by their presence and abundance, provide some indication, either qualitatively or quantitatively or both, of the prevailing environmental conditions.

  4. Advantages Diverse Sedentary Long-lived Well characterised Disadvantages Aggregated distribution Seasonal variation River drift Difficult to get reliable quantitative samples. BIOLOGICAL ASSESSMENTMacroinvertabrates

  5. BIOLOGICAL ASSESSMENT CHEMICAL AND BIOLOGICAL ASSESSMENT • Overall should show a similar picture. • There are local differences: • England and Wales > 20% river length (8500Km) chem and biological assessments > 2 grades diff. • Schemes are independent, and measure different features.

  6. CHEMICAL vs. BIOLOGICAL ASSESSMENT Biological Assessment better than Chemical. • longer term picture (community structure) • can show periodic pollution • also responds to a wide range of chemical contaminants • contaminants at low levels may bioaccumulate (gives a response) • Drawbacks to Biological Assessment • Discontinuous (seasonal) method • dependent on habitat • labour intensive and requires taxonomical skills • invasive (potentially disruptive to riverbed) • errors (drift of organisms) • Sampling technique critical

  7. BIOLOGICAL ASSESSMENT • Qualitative Sampling. The number of taxa recovered depends on: • sampling effort (taxon accretion curve) • operator and technique, • 5 Surber samples or 10-20 min kick sampling yields 80% of taxa, • 3 min kick sampling by experienced operators yields 40 to 50% of taxa • Identification • level of taxonomic skill (ie determination of species versus families) • Data Processing

  8. BIOLOGICAL ASSESSMENT STATISTICAL CONSIDERATIONS • Quantitative Sampling. • More demanding. • Used to determine relative population density. • High levels of confidence within narrow limits requires large numbers of samples. • Number of samples required to estimate population density is approx:

  9. BIOLOGICAL ASSESSMENT n = (st/Dx)2 x: mean number of taxa per sample, n: number of samples, s: standard deviation, D: index of precision, t: Student`s t for the required level f confidence. eg if x = 10, s = 5, to obtain estimate of pop density within 10% of true value with 95% confidence, require 100 samples. BUT BEWARE OF LIMITATIONS.

  10. BIOLOGICAL ASSESSMENT DATA ANALYSIS AND INTERPRETATION • Series of comparisons. • Spatial, or • Temporal, or • Both

  11. BIOLOGICAL ASSESSMENT DATA ANALYSIS AND INTERPRETATION • Can we distinguish between an anthropogenic impact and one from coincidental factors? • To determine the effects of pollution, need a good understanding of the conditions in unpolluted waters. • Must consider both numbers of species and their relative abundance. • Complexity - hence use of Indexes.

  12. BIOLOGICAL ASSESSMENT BIOTIC Indexes - Diversity Indexes • Developed to study stability versus diversity in ecosystems. • Many approaches, differ in weighting given to the number of species and to the distribution of individuals between species. • Many are not independent of sample size. • Practical advantage is the low taxonomical skill requirement.

  13. BIOLOGICAL ASSESSMENT BIOTIC Indexes. All Indexes are empirical. • Saprobien Indexes (Knopp 1954) • Central and Eastern Europe. • Recognise 4 sabrobic zones and relative abundance (eg rare, frequent, abundant) • Organism allocation to pollution zones. • Trent Biotic Index (Woodiwiss 1964) • allocate macrofauna to groups • low taxonomic skill requirement • abundance not considered

  14. Biotic Indexes Lothians Index (Graham 1964) • similar to Trent, different scales Chandler Biotic Index (Chandler 1970) • 5 levels of abundance considered (weighting of scores) Biological Monitoring Working Party, BMWP (1979) • each family is scored, scores summed • no account taken of abundance of individuals Average Score per Taxon (ASPT) • is BMWP score divided by number of Taxa (families) • better when sampling technique varies

  15. BIOLOGICAL ASSESSMENT River Invertebrate Prediction and Classification Scheme • RIVPACS (Multivariate analysis) • Input a minimum of 8 physical parameters: • latitude • longitude • altitude • distance from source • discharge • width • depth • substratum composition.

  16. Actual BMWP EQI = RIVPACS BMWP General Quality Assessment (GQA)- Biological - • Environment Agency • Ecological Quality Index (EQI) • uses the predicted diversity (BMWP, ASPT) for the river as a baseline (calculated by RIVPACS) • numerical ratio between observed and predicted values gives index. • River stretch graded “a ----- f” based on EQI value

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