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ANNEX 11: SURFACE WATER BIOLOGICAL STANDARDS - BIOLOGICAL STANDARDS FOR FRESHWATER AND BRACKISH LOCHS
Surface water biological standards for freshwater and brackish lochs in Scotland are presented in Tables A to F below. The standards are presented as 'ecological quality ratios' applicable either to all lochs or to any loch of a specified type, as indicated in the relevant table.
The standards are compared with the measured ecological quality ratio. This is derived by comparing the monitored biological conditions pertaining in the loch with the conditions expected under reference conditions.
Reference conditions represent conditions before intensification of agriculture and the development of extensive waste water collection and disposal systems from centres of population. Reference conditions are predicted based on relevant characteristics of the loch concerned. The methods for predicting reference conditions have been developed using data collected from networks of reference sites in the UK or a mixture of sites in the UK and elsewhere in Europe. Low levels of intensive agriculture in the catchment of lochs and low population density, together with the absence of other direct pressures such as fish cage units were used to select reference lochs. These criteria were supported with data from palaeolimnological studies (which can provide a timeline of ecological change in a loch) where such information was available.
Where the standards apply to specified loch types, the characteristics differentiating the loch types may vary depending on the plant or animal group and the impacts being assessed. For example, standards for the biomass of phytoplankton in the water column in a loch will be sensitive to the alkalinity of the water and the depth of the loch, whereas benthic invertebrates on the bed of a loch and responding to acidification pressure are unlikely to be sensitive to differences between lochs in mean depth.
Table A: Phytoplankton (i) standards for lochs - chlorophyll a
Standards for the degree to which the biomass of phytoplankton taxa (as represented by the annual mean chlorophyll a concentration) differ from the biomass of those phytoplankton taxa (annual mean chlorophyll a concentration) expected under reference conditions. |
|---|
| Ecological quality ratio |
|---|
Column 1 | Column 2 | Column 3 | Column 4 | Column 5 | Column 6 | Column 7 | Column 8 |
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Loch characteristics (ii) | Marl, shallow; and high alkalinity, shallow. | High alkalinity, very shallow. | Medium alkalinity, deep; medium alkalinity, shallow; low alkalinity, deep; and low alkalinity, shallow at mid-altitude. | Medium alkalinity, very shallow. | Low alkalinity, shallow at low altitude & with < 75 % by area of the soils in the catchment being peat. | Low alkalinity, shallow at low altitude & with = 75 % by area of the soils in the catchment being peat. | Low alkalinity, very shallow. |
High | 0.55 | 0.63 | 0.50 | 0.63 | 0.50 | 0.50 | 0.63 |
Good | 0.32 | 0.30 | 0.33 | 0.34 | 0.29 | 0.30 | 0.33 |
Moderate | 0.16 | 0.15 | 0.165 | 0.17 | 0.145 | 0.15 | 0.165 |
Note to Table A
(i)The term 'phytoplankton' refers to solitary and colonial unicellular algae and cyanobacteria that live in the water column, at least for part of their lifecycle.
(ii)For the purposes of Table A, the geological and depth characteristics of lochs applicable to Columns 2 to 8 are classified in accordance with paragraphs 1 to 5 of Annex 2 above
"mid-altitude" means = 200 - 800 metres above mean sea level.
"low altitude" means < 200 metres above mean sea level
Table B: Phytoplankton standards for lochs - percentage cyanobacteria
Standards for the degree to which the annual mean percentage of cyanobacteria differ from the annual mean percentage of cyanobacteria expected under reference conditions. |
|---|
| Ecological quality ratio |
|---|
Column 1 | Column 2 | Column 3 | Column 4 |
|---|
Geological characteristics* | High Alkalinity | Medium Alkalinity | Low alkalinity |
High | 0.97 | 0.95 | 0.97 |
Good | 0.82 | 0.77 | 0.82 |
Moderate | 0.61 | 0.61 | 0.61 |
Note to Table B
*For the purposes of Table B, the geological characteristics of lochs applicable to Columns 2, 3 and 4 are classified in accordance with paragraphs 2 to 4 of Annex 6 above.
Table C: Phytobenthos standards for lochs
Standards for the degree to which the relative annual mean abundances of nutrient-sensitive and nutrient-tolerant groups of diatom taxa differ from the relative annual mean abundances of these groups of taxa expected under reference conditions |
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| Ecological quality ratio |
|---|
Column 1 | Column 2 | Column 3 |
|---|
| Low alkalinity lochs | Moderate alkalinity lochs; high alkalinity lochs; and marl lochs |
High | 0.90 | 0.90 |
Good | 0.63 | 0.66 |
Moderate | 0.44 | 0.44 |
Table D: Aquatic macrophyte (i) standards for lochs
Standards for the degree to which the annual mean abundance of disturbance-sensitive macrophyte taxa differ from the annual mean abundance of those taxa expected under reference conditions |
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| Ecological quality ratio |
|---|
Column 1 | Column 2 |
|---|
High | 0.80 |
Good | 0.60 |
Moderate | 0.40 |
Poor | 0.20 |
Note to Table D
(i)The term 'macrophyte' refers to larger plants, typically including flowering plants, mosses and larger algae, but not including single-celled phytoplankton or diatoms.
Table E: Benthic invertebrate standards for lochs (1)
Standards for the degree to which the annual mean ratio of nutrient-sensitive to nutrient-tolerant chironomid taxa differ from the annual mean ratio of such taxa expected under reference conditions |
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| Ecological quality ratio |
|---|
Column 1 | Column 2 |
|---|
High | 0.78 |
Good | 0.60 |
Moderate | 0.40 |
Poor | 0.20 |
Table F: Benthic invertebrate standards for lochs (2)
| Standards indicating the degree to which the annual mean taxon sensitivity, niche breadth and abundance of benthic invertebrate taxa has been altered from that expected under reference conditions as a result of acidification |
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| Ecological quality ratio |
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Column 1 | Column 2 | Column 3 |
|---|
Geological characteristics | Low alkalinity with < 75 % by area of the soils in the catchment being peat | Low alkalinity with = 75 % by area of the soils in the catchment being peat. |
High | 0.867 | 0.845 |
Good | 0.725 | 0.506 |
Moderate | 0.596 | - |
Note to Table F
*For the purposes of Table F, the geological characteristics of lochs applicable to Columns 2 and 3 are classified in accordance with paragraphs 2 to 4 of Annex 6 above.
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