Lakes and Watercourses
Lakes and Watercourses Lakes and Watercourses
Class 1 in the overall index indicates that the fish fauna of the watercourse consists of a large number of species with high diversity, many fishes with a high proportion of salmonids having a high reproduction level. A classification around class 3 indicates a watercourse close to the median for Swedish watercourses. Class 5 indicates an ecosystem poor in species and individuals and with an absence of salmonids. Assessment of deviation from reference values Note that deviation from reference values for lakes (Table 46) is not calculated for the parameters ”Presence of species and stages sensitive to acidification”, ”Proportion of tolerant fish species” and ”Proportion of alien species”, the deviation can instead be obtained directly by comparing the recorded value with the classes in table 46. In these cases the value for class 1 is the result obtained in waters with no or insignificant impact. Class boundaries have been adjusted to existing parameters and background data. With a few isolated exceptions, the 50th, 25th, 10th and 5th percentiles have been used for one-sided parameters, which means that 50 per cent of the background data will fall within class 1. The 2nd, 5th, 10th and 25th percentiles and the 75th, 90th, 95th and 98th percentiles, respectively, have been used for double-sided parameters. Here, too, 50 per cent of the background data falls within class 1. Note that reference values for watercourses are only calculated for the ”Number of species” parameter. The parameters ”Weight/100 m 2 ” to ”Proportion of alien fish species” are calculated as described in the footnote. In these cases the value for class 1 is the result obtained in waters with no or insignificant impact. Comments The assessments must be based on fish surveys carried out in accordance with the instructions given in the Swedish EPA Environmental Monitoring Handbook. Hence, lakes having a surface area of less than 10 ha should not be included. Assessment of current conditions and deviations should also be made with a degree of insight. This is particularly so where the absence of species and stages forms part of the assessment (eg, proportion of species sensitive to acidification and proportion of alien species). In exceptional cases, natural variations may lead to erroneous interpretations. Assessment of lakes over 500 m above sea level should be made with great caution owing to the absence of data on high altitude lakes and lakes with predominantly salmonid assemblages. The background data on watercourses in lowland areas is similarly limited. Help with calculations may be obtained from the data host for fish (Institute of Freshwater Research, National Board of Fisheries). 75
TABLE 46. DEVIATION from reference value, lakes. For the time being, calculations should only be made for lakes below 500 m above sea level. Background data on higher altitude lakes is too limited for reliable assessment. Calculations are only made for lakes that can be assumed to contain, or have contained, fish. Class Description Recorded value/reference value No. of species 1 Species diversity 1 Biomass 1 Number 1 1 No or insignif. deviation > 0.80 > 1.00 0.65 – 1.50 0.60 – 1.40 2 Slight deviation 0.62 – 0.80 0.83 – 1.00 0.45 – 0.65 or 0.37 – 0.60 or 1.50 – 2.15 1.40 – 2.15 3 Significant deviation 0.42 – 0.62 0.60 – 0.83 0.28 – 0.45 or 0.22 – 0.37 or 2.15 – 2.70 2.15 – 2.80 4 Large deviation 0.32 – 0.42 0.38 – 0.60 0.10 – 0.28 or 0.10 – 0.22 or 2.70 – 3.40 2.80 – 3.50 5 Very large deviation ≤ 0.32 ≤ 0.38 < 0.10 or < 0.10 or > 3.40 > 3.50 Class Description Recorded value/reference value Proportion pisc. 1 Proportion Proportion Proportion cyprinids 1 species and tolerant stages sensitive species 3 to acidification 2 1 No or insignificant deviation 1.00 1.00 a) < 0.10 2 Slight deviation 0.65 – 1.00 1.00 – 1.28 0.10 – 0.25 3 Significant deviation 0.40 – 0.65 1.28 – 1.67 b) 0.25 – 0.50 4 Large deviation 0.23 – 0.40 1.67 – 1.89 0.50 – 1.00 5 Very large deviation < 0.23 > 1.89 c) 1.00 Class Description Proportion alien species 4 Overall index 5 1 No or insignificant deviation 0 ≤ 1.7 2 Slight deviation 0 – 0.10 1.7 – 2.1 3 Significant deviation 0.10 – 0.20 2.1 – 2.6 4 Large deviation 0.20 – 0.50 2.6 – 3.0 5 Very large deviation > 0.50 > 3.0 1 The deviation is calculated as the ratio between recorded value and the reference value. The reference value is set with reference to Table 47. 2 a) Presence of spined loach (Cobitis taenia) or crayfish or juvenile roach (Rutilus rutilus), minnow (Phoxinus phoxinus), burbot (Lota lota), char (Salvelinidae), whitefish (Coregonidae) or vendace (Coregonus albula). b) Presence of perch (Perca fluviatilis), trout (Salmo trutta), bullhead (Cottidae), ruffe (Gymnocephalus cernuus), burbot (Lota lota), grayling (Thymalus thymalus) char, whitefish or vendace (Coregonus albula). c) Species absent (have disappeared) or only mature/large individual specimens of perch or pike are present. 3 Calculated as percentage by weight of crucian carp (Carassius carassius) and/or tench (Tinca tinca) out of the total catch. This parameter is only used in lakes where one of these species has been caught. 4 Calculated as percentage by weight of fish species not native to Sweden out of the total catch. 5 The overall assessment of deviation is obtained by calculating the mean class value for all parameters included (maximum 9 parameters). 76
- Page 25 and 26: Mean concentration of total phospho
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- Page 29 and 30: Comments Classifications must be ba
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- 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
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- 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
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- 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: TABLE 45. CURRENT CONDITIONS: fish,
- Page 79 and 80: TABLE 48. DEVIATION from reference
- Page 81 and 82: TABLE 48. (Contd.) Proportion of al
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- 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
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- Page 102 and 103: APPENDIX 3 Dace Stäm Leuciscus leu
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TABLE 46.<br />
DEVIATION from reference value, lakes. For the time being, calculations should only be<br />
made for lakes below 500 m above sea level. Background data on higher altitude lakes is<br />
too limited for reliable assessment. Calculations are only made for lakes that can be<br />
assumed to contain, or have contained, fish.<br />
Class Description Recorded value/reference value<br />
No. of species 1 Species diversity 1 Biomass 1 Number 1<br />
1 No or insignif. deviation > 0.80 > 1.00 0.65 – 1.50 0.60 – 1.40<br />
2 Slight deviation 0.62 – 0.80 0.83 – 1.00 0.45 – 0.65 or 0.37 – 0.60 or<br />
1.50 – 2.15 1.40 – 2.15<br />
3 Significant deviation 0.42 – 0.62 0.60 – 0.83 0.28 – 0.45 or 0.22 – 0.37 or<br />
2.15 – 2.70 2.15 – 2.80<br />
4 Large deviation 0.32 – 0.42 0.38 – 0.60 0.10 – 0.28 or 0.10 – 0.22 or<br />
2.70 – 3.40 2.80 – 3.50<br />
5 Very large deviation ≤ 0.32 ≤ 0.38 < 0.10 or < 0.10 or<br />
> 3.40 > 3.50<br />
Class Description Recorded value/reference value<br />
Proportion pisc. 1 Proportion Proportion Proportion<br />
cyprinids 1 species <strong>and</strong> tolerant<br />
stages sensitive species 3<br />
to acidification 2<br />
1 No or insignificant deviation 1.00 1.00 a) < 0.10<br />
2 Slight deviation 0.65 – 1.00 1.00 – 1.28 0.10 – 0.25<br />
3 Significant deviation 0.40 – 0.65 1.28 – 1.67 b) 0.25 – 0.50<br />
4 Large deviation 0.23 – 0.40 1.67 – 1.89 0.50 – 1.00<br />
5 Very large deviation < 0.23 > 1.89 c) 1.00<br />
Class Description Proportion alien species 4 Overall index 5<br />
1 No or insignificant deviation 0 ≤ 1.7<br />
2 Slight deviation 0 – 0.10 1.7 – 2.1<br />
3 Significant deviation 0.10 – 0.20 2.1 – 2.6<br />
4 Large deviation 0.20 – 0.50 2.6 – 3.0<br />
5 Very large deviation > 0.50 > 3.0<br />
1 The deviation is calculated as the ratio between recorded value <strong>and</strong> the reference value. The reference<br />
value is set with reference to Table 47.<br />
2 a) Presence of spined loach (Cobitis taenia) or crayfish or juvenile roach (Rutilus rutilus), minnow<br />
(Phoxinus phoxinus), burbot (Lota lota), char (Salvelinidae), whitefish (Coregonidae) or vendace<br />
(Coregonus albula).<br />
b) Presence of perch (Perca fluviatilis), trout (Salmo trutta), bullhead (Cottidae), ruffe (Gymnocephalus<br />
cernuus), burbot (Lota lota), grayling (Thymalus thymalus) char, whitefish or vendace (Coregonus albula).<br />
c) Species absent (have disappeared) or only mature/large individual specimens of perch or pike are<br />
present.<br />
3 Calculated as percentage by weight of crucian carp (Carassius carassius) <strong>and</strong>/or tench (Tinca tinca) out<br />
of the total catch. This parameter is only used in lakes where one of these species has been caught.<br />
4 Calculated as percentage by weight of fish species not native to Sweden out of the total catch.<br />
5 The overall assessment of deviation is obtained by calculating the mean class value for all parameters<br />
included (maximum 9 parameters).<br />
76
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