Lakes and Watercourses

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TABLE 1. Continued Area/parameter Lakes/ Current Deviation water- conditions from courses reference value Aquatic plants Submerged and floating-leaved plants, number of species and indicator ratio** l + + Periphyton – diatoms IPS index w + - IDG index w + - Benthic fauna Shannon’s diversity index*** l/w + + Danish fauna index*** l/w + + ASPT index*** l/w + + Acidity index l/w + + BQI index**** l + + O/C index**** l + + Fish Naturally occurring Swedish species l/w + + Species diversity of native species l + + Biomass of native species l/w + + Number of individuals of native l/w + + species Proportion of cyprinids l - + Proportion of Piscivorous fish l + + Proportion of salmonids w + + Salmonid reproduction w + + Species and stages sensitive to acidification l/w - + Species tolerant of low oxygen concentrations l - + Proportion of biomass comprising l/w - + alien species Composite value derived from (part of) the above l/w + + * lake sediment ** indicator value for assessing deviation from reference value *** in lakes: the littoral zone **** the profundal zone 15
16 The current conditions scale in this report is based on the levels occurring in Sweden for each parameter and, to some extent, on the biological and other conditions characterising different levels. Hence, as far as possible, the boundaries between the classes coincide with clear changes on the relevant gradient. Where it has not been possible to identify levels where such changes occur, boundaries have been decided statistically on the basis of the most representative data possible, or arbitrarily on the basis of an overall judgement of what can be considered reasonable. The width of the classes varies, depending on the way each parameter changes along a gradient from low to high or vice versa. In some cases, changes in the lower range of the scale are particularly significant. Here scales have been graduated to give them sufficient resolution in this respect. In other cases, changes occur gradually along a gradient and the boundaries between classes are more evenly distributed along the scale. The way scales have been developed for individual parameters may be seen in each chapter. It should be emphasised that the assessment scales cannot easily be interpreted as representing ”good” or ”bad” environmental quality. The parameters must be evaluated individually in the light of the quality aspects they are intended to reflect. This applies particularly to the scales for assessment of current conditions. A number of examples serve to illustrate this. Chemical parameters such as metals, organic pollutants and alkalinity are fairly closely related to water quality in the sense that increasing concentrations (decreasing for alkalinity) can generally be said to reflect a growing risk of negative effects on aquatic organisms or use of water resources. The scale for total phosphorus reflects conditions for increasing quantities of phytoplankton in water. From an aesthetic viewpoint, for bathing, water supply etc, an increase of this kind is generally considered undesirable, but in production terms, the scale should have been placed the other way round. This has not been done because the total phosphorus parameter is primarily intended to indicate conditions for the presence of phytoplankton and associated adverse effects. This rationale also underlies the form chosen for assessment scales for other parameters. Thus, classification of the state of fish assemblages is based on expected fish numbers and diversity of fish species. Class 1 (lakes) indicates a large number of fish, a large number of species with high diversity and a high proportion of piscivorous species, ie, a rich and diverse fish community. Class 1 watercourses feature a large number of salmonids with high breeding success. Class 3 indicates that the fish assemblages in the lake or watercourse are average for Swedish waters, whereas class 5 indicates assemblages poor in numbers of species and individuals. In the case of parameters where contradictory interpretations or evaluations are possible, the direction of the scales has been decided
Page 1 and 2: Environmental Quality Criteria - La
Page 3 and 4: TO ORDER Swedish Environmental Prot
Page 5 and 6: Reference Group Mats Bengtsson, Swe
Page 7 and 8: Summary This report on lakes and wa
Page 11 and 12: included. In addition to a large nu
Page 13 and 14: ased estimates are used. Given that
Page 15: TABLE 1. SUMMARY of parameters incl
Page 19 and 20: (in Swedish with English summary).
Page 21 and 22: conditions for watercourse flora an
Page 23 and 24: show the availability of nitrogen i
Page 25 and 26: Mean concentration of total phospho
Page 27 and 28: TABLE 9. DEVIATION from reference v
Page 29 and 30: Comments Classifications must be ba
Page 31 and 32: winter/spring, i.e. ice-covered per
Page 33 and 34: Light conditions Introduction Light
Page 35 and 36: TABLE 13. CURRENT CONDITIONS: turbi
Page 37 and 38: Acidity / acidification Introductio
Page 39 and 40: industrial pH). The change in acidi
Page 41 and 42: The pre-industrial concentration of
Page 43 and 44: very high degree of reliability and
Page 45 and 46: TABLE 19. CURRENT CONDITIONS: metal
Page 47 and 48: TABLE 22. DEVIATION from reference
Page 49 and 50: TABLE 24. (continued) Cu Zn Cd Pb C
Page 51 and 52: Swedish EPA (1993): Metals and the
Page 53 and 54: Assessment of current conditions TA
Page 55 and 56: TABLE 29. CURRENT CONDITIONS: poten
Page 57 and 58: TABLE 32. DEVIATION from reference
Page 59 and 60: References Cronberg, G., Lindmark,
Page 61 and 62: (see Appendix 1). If submerged and
Page 63 and 64: References Andersson, B. (1998): Va
Page 65 and 66: The genera in question and their tr
Page 67 and 68:
Benthic fauna Introduction Benthic
Page 69 and 70:
TABLE 41. CURRENT CONDITIONS: botto
Page 71 and 72:
Comments The assessment must be bas
Page 73 and 74:
has yielded better results than did
Page 75 and 76:
TABLE 45. CURRENT CONDITIONS: fish,
Page 77 and 78:
TABLE 46. DEVIATION from reference
Page 79 and 80:
TABLE 48. DEVIATION from reference
Page 81 and 82:
TABLE 48. (Contd.) Proportion of al
Page 84 and 85:
Presentation of data When using the
Page 86 and 87:
APPENDIX 1 Ceratophyllum demersum 1
Page 88 and 89:
APPENDIX 2 Calculation of index and
Page 90 and 91:
APPENDIX 2 Table 1b. Indicator gene
Page 92 and 93:
Genus Indicator value -------------
Page 94 and 95:
APPENDIX 2 45 Planorbis sp. 46 Anis
Page 96 and 97:
APPENDIX 2 214 Leuctra hippopus 215
Page 98 and 99:
APPENDIX 2 384 Tinodes waeneri 385
Page 100 and 101:
APPENDIX 2 (6) O/C index (Wiederhol
Page 102 and 103:
APPENDIX 3 Dace Stäm Leuciscus leu
Page 106:
REPORT 5050 Environmental Quality C
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Lakes and Watercourses

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