257 northeastern USA

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257 northeastern USA lakes and reservoirs

Soil & Water Conservation Society of Metro Halifax (SWCSMH)

July 26, 2006

Excerpts from:

Dixit, S.S., Smol, J.P., Charles, D.F., Hughes, R.M., Paulsen, S.G., and Collins, G.B. 1999. Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms. Can. J. Fish. Aquat. Sci. 56:131-152.

Conclusions/Summary

Diatom assemblages were selected as indicators of lake condition and to assess historical lake water quality changes in 257 lakes in the northeastern United States. The "top" (surface sediments, present-day) and "bottom" (generally from >30 cm deep, representing historical conditions) samples from sediment cores collected from lakes and reservoirs were analyzed for diatom assemblages. The distribution of diatom species was closely related to several environmental variables, primarily lake water pH, total phosphorus, and chloride. Using weighted-averaging calibration and regression approaches, predictive models were constructed to infer these variables from the diatom assemblages. The diatom-based inference models were then used to assess the current status of lake water quality and to assess historical changes in lake water conditions in natural lakes over the past 150 years. Changes were also assesed in reservoirs.

Population estimates of historical changes in limnological variables were made for all lakes of the northeast United States and also for lakes in the Adirondacks, New England Uplands, and Coastal Lowlands/Plateau ecoregions.

The extent of cultural impact has been quite variable among the ecoregions, with marked water quality deterioration occurring in hundreds of lakes. Chloride and phosphorus levels have increased, especially in lakes that currently have high concentrations. Low-pH lakes have become more common in all three ecoregions. The maximum abundance of low-pH lakes was recorded in the Adirondacks, an area receiving the highest acidic precipitation in the northeast. In the Coastal Lowlands/Plateau, there has been a clear increase in eutrophic lakes, as inferred by total phosphorus. This was accompanied by a marked increase in the number of lakes with high chloride levels.

Chloride levels:

Marked population changes have occurred in Cl levels in natural lakes since pre-1850. The background levels of Cl in surface waters should be in the range of 50 - 100 µeq/L unless there are other sources than "clean" rainfall and clean seepage. A level of 100 µeq/L indicates disturbance of some sort, whereas <50 µeq/L is expected in pristine wilderness waters lacking natural sources.

The population of lakes that have Cl levels <200 µeq/L has increased threefold (6-18%), whereas the population of lakes that have Cl levels <100 µeq/L has decreased by 5%.

pH levels:

The lake water pH data for the target population of natural lakes indicate that the percentages of both acidic (pH<5.6) and high-pH (>7.5) lakes have increased since pre-industrial times, whereas the number of lakes that had pH between 5.6 and 7.5 has declined. Among ecoregions, ADIR (Adirondacks) contains the highest proportion of acidic lakes (23%). Although the region also contained some naturally acidic lakes (11%), diatom data clearly indicate that the proportion of acidic lakes has greatly increased. In the NEU (New England Uplands) and CLP (Coastal Lowlands/Plateau) ecoregions, the increases have been from 1 to 7% and from 0 to 18%, respectively. The pH-related population changes were small in reservoirs. On a regional basis, changes in any of the pH groups were no more than 2%.

Alkalinization of high-pH lakes:

Although the overall population of naturally alkaline sites (pH>7.5) in the northeast has increased from 46 to 49%, in the ADIR (Adirondacks) and CLP (Coastal Lowlands/Plateau) ecoregions, their populations have increased by 10 and 15%, respectively, whereas in the NEU (New England Uplands) ecoregion, it has declined by 6% since pre-industrial times.

Although the lake water pH decline is mainly due to acidic precipitation in the region, many factors may be responsible for the alkalinization of high-pH lakes.

Possible mechanisms include:

land use changes that increase cation export,
eutrophication accompanied by increased pH,
greater carbonate weathering in watersheds as a result of sulphate and nitrate deposition,
sulphate and nitrate reduction by bacteria in lakes, and
enhanced algal uptake of nitrate that is replaced by bicarbonates.

Although the relative importance of these processes probably varies among ecoregions, the diatom data clearly indicated that, due to human disturbances, the pH in many alkaline sites has been gradually increasing during this century. These inferred pH data are vital in understanding the effects of acidic precipitation on freshwaters and in developing management strategies to document lake responses to emission reduction scenarios.

TP levels:

The target population data for inferred TP suggest that, on a regional basis, the percentages of oligotrophic (TP<10 µg/L), mesotrophic (TP=10-30 µg/L), and eutrophic (TP>30 µg/L) lakes have not changed much for both natural lakes and reservoirs. However, marked population changes are evident for individual ecoregions.

Although natural lakes in the ADIR (Adirondacks) ecoregion had experienced distinct change in lake water pH, the region has not been adversely affected by nutrient enrichment since pre-industrial time. No eutrophic lakes were detected either.

For the natural lakes of the NEU (New England Uplands) ecoregion, the population of eutrophic lakes has increased (from 2 to 4%) and of oligotrophic lakes has declined (from 41 to 38%) whereas the population of mesotrophic lakes has remained relatively unchanged (57-58%). Reservoirs in the NEU region have responded somewhat differently. The population of eutrophic sites has declined (from 22 to 9%), and both oligotrophic and mesotrophic reservoirs have increased from 12 to 17 and from 65 to 75%, respectively.

An increasing number of CLP (Coastal Lowlands/Plateau) ecoregion lakes have undergone nutrient enrichment. In natural lakes, the proportion of eutrophic and oligotrophic lakes have increased from 6 to 8 and from 48 to 63%, respectively, whereas the population of mesotrophic lakes has declined from 46 to 29% since pre-industrial/pre-European times. Although 38% of the reservoirs were eutrophic in the past, their population has increased to 46%. The populations of both oligotrophic and mesotrophic reservoirs have declined in the CLP (Coastal Lowlands/Plateau) ecoregion.

Although there are more eutrophic lakes in the northeast than in the past, the data also suggest that there were some naturally productive lakes in the region. Land use, land cover, physiography, soil, vegetation cover, and bedrock and surficial geology can greatly influence the eutrophic status of lakes. Although lakes experience changes in trophic state naturally, the major limnological changes that have been identified in this study are mainly due to increased human disturbances in the lakes' drainage basins. These disturbances increase the loads of sediment and nutrients and lead to accelerated eutrophication and water quality degradation.

Forest cover:

Anthropogenic activity in watersheds generally increases biological productivity in waters as a result of nutrient inputs. Forest cover can act as either a sink or a source of nutrients to lakes, and it has been found that removal of terrestrial vegetation generally introduces nutrients to a lake through leaching processes.

Planning realistic trophic state targets:

The diatom-inferred regional patterns for current TP not only closely follow the regional patterns of archival TP for the glaciated portion of the northeastern United States, but also provide data on background TP levels in northeastern waters. These regional population data are necessary to provide the rationale for prioritizing restoration efforts and planning realistic trophic state targets.

Study area and lake selection

In EMAP-SW (EPA's Environmental Monitoring and Assessment Program -Surface Waters), 257 lakes and reservoirs were sampled for multiple indicators during July and August of 1991-1994 in Maine, New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New York, and New Jersey. The study area can be broadly divided into three ecoregions: Adirondacks (ADIR), New England Uplands (NEU), and Coastal Lowlands/Plateau (CLP). An ecoregion framework has been useful for assessing regional water quality and setting regionally attainable restoration goals.

The ADIR and NEU ecoregions contained the majority of natural lakes, whereas the majority of sites in the CLP ecoregion were reservoirs. A reservoir was defined as any lake that was created by human activity, where there was probably not a lake in presettlement times.

The site selection was based on a statistical design so that the probability of including any particular site can be calculated. The 257 study sites represent the "target population" of 10,608 lakes and reservoirs in the region that are at least 1 m deep and have a surface area of 1 - 10,000 ha. Because most of these sites are <10 ha in size, a random sample of sites would have been dominated by small water bodies. This situation was corrected by varying the inclusion probability by size so that a reasonable number of large water bodies were also included. The inverse of the inclusion probability of a site is its weighting factor. By using the weighting factor, it is possible to estimate the number of sites in the target population represented by each sampled site.

19 reservoir-sites were problematic. Of the remaining 238 sites, 159 were natural lakes and 79 were reservoirs. Among the 159 natural lakes, 139 were the probability sites, representing the target population of 4638 lakes in the northeast. Among the 79 reservoirs, 78 were probability sites, representing an estimated 4906 reservoirs in the northeast.

Diatom inference model

Table: Number of occurrences, maximum and mean occurrences, and weighted-averaging optima for pH, TP, and Cl for the 235 common diatom taxa found in the 309 sites (238 EMAP and 71 Adirondack PIRLA sites) in the northeastern United States

No. Taxon No. of
occurrences Optima

pH TP
(µg/L) Cl
(µeq/L)

1 Achnanthes altaica 61 6.8 7 20

2 Achnanthes austriaca var. helvetica 175 7.1 10 57

3 Achnanthes bicapitata 53 7.4 10 69

4 Achnanthes clevei 12 8.1 7 244

5 Achnanthes detha 223 7.3 10 46

6 Achnanthes didyma 65 7.4 7 24

7 Achnanthes exigua 61 8.0 13 41

8 Achnanthes exigua var. hetrovelvata 15 7.8 11 85

9 Achnanthes flexella 70 7.5 9 28

10 Achnanthes hungarica 11 7.9 47 391

11 Achnanthes lanceolata 89 7.7 22 113

12 Achnanthes lanceolata var. rostrata 45 8.0 15 90

13 Achnanthes lapidosa 13 7.8 11 135

14 Achnanthes laterostrata 58 7.6 7 42

15 Achnanthes levanderi 36 7.2 8 58

16 Achnanthes linearis 164 7.6 12 53

17 Achnanthes marginulata 152 6.6 7 24

18 Achnanthes minutissima 292 7.8 13 105

19 Achnanthes peragalli 34 7.7 9 38

20 Achnanthes stewartii 14 7.5 12 152

21 Achnanthes suchlandtii 64 7.6 8 49

22 Actinella punctata 59 5.5 9 25

23 Amphora ovalis 123 8.0 22 118

24 Amphora perpusilla 30 8.3 25 592

25 Amphipleura pellucida 30 7.9 18 73

26 Anomoeoneis follis 22 6.9 9 13

27 Anomoeoneis serians var. brachysira 181 6.4 8 15

28 Anomoeoneis serians 50 5.5 6 14

29 Anomoeoneis vitrea 246 7.6 11 40

30 Asterionella formosa 209 7.6 10 128

31 Asterionella ralfsii var. americana (<45 µm) 13 5.3 21 38

32 Asterionella ralfsii var. americana (>45 µm) 135 5.8 11 24

33 Aulacoseira ambigua 241 7.5 14 89

34 Aulacoseira crassipunctata 16 5.5 23 68

35 Aulacoseira distans 169 6.6 8 24

36 Aulacoseira distans var. humilis 25 7.4 10 43

37 Aulacoseira distans var. nivalis 44 6.3 7 19

38 Aulacoseira distans var. nivaloides 109 6.9 11 28

39 Aulacoseira distans var. tenella 174 7.2 10 55

40 Aulacoseira granulata 24 7.8 29 241

41 Aulacoseira italica subsp. subarctica 75 7.5 8 70

42 Aulacoseira italica subsp. subarctica f. tenussima 13 7.9 11 180

43 Aulacoseira italica var. valida 30 7.4 13 47

44 Aulacoseira lirata f. biseriata 12 6.8 7 30

45 Aulacoseira lirata var. lacustris 43 6.5 9 19

46 Aulacoseira lirata 185 6.8 9 25

47 Aulacoseira nygaardii 100 6.5 10 21

48 Aulacoseira perglabra var. floriniae 79 6.6 7 27

49 Aulacoseira perglabra 39 6.0 5 10

50 Caloneis ventricosa 41 7.5 9 36

51 Cocconeis placentula 126 8.0 28 387

52 Cyclotella comta 200 7.4 6 44

53 Cyclotella meneghiniana 26 8.3 66 1113

54 Cyclotella michiganiana 120 8.0 9 142

55 Cyclotella ocellata 19 7.9 6 58

56 Cyclotella stelligera 285 7.3 7 59

57 Cymbella amphicephala v. hercynica 46 7.6 14 65

58 Cymbella cf. aequalis 95 7.7 12 19

59 Cymbella cesatii 55 7.8 10 19

60 Cymbella cistula 41 8.0 17 36

61 Cymbella cuspidata 53 7.4 13 35

62 Cymbella delicatula 25 8.1 8 120

63 Cymbella descripta 32 7.8 10 18

64 Cymbella cf. gaeumanii 58 6.6 8 29

65 Cymbella hebedrica 112 6.0 7 11

66 Cymbella lunata 141 7.0 9 24

67 Cymbella microcephala 135 7.9 11 34

68 Cymbella minuta f. latens 12 7.8 12 81

69 Cymbella minuta var. minuta 146 7.7 13 103

70 Cymbella minuta var. silesiaca 29 7.7 10 42

71 Cymbella cf. schubartii 36 6.5 12 21

72 Cymbella sp. 1 PIRLA 59 5.7 7 12

73 Diatoma hiemale var. mesodon 12 6.9 6 26

74 Diploneis marginestriata 62 7.7 11 56

75 Diploneis ovalis 44 7.8 10 98

76 Epithemia species 23 8.0 11 72

77 Eunotia bidentula 62 5.6 10 34

78 Eunotia bigibba var. pumila 13 5.9 10 18

79 Eunotia carolina var. 1 PIRLA 65 5.9 11 53

80 Eunotia curvata 172 6.1 9 24

81 Eunotia elegana 35 7.1 9 30

82 Eunotia exigua 127 5.9 10 20

83 Eunotia fallax 26 6.1 9 45

84 Eunotia flexuosa var. eurycephala 16 6.6 7 36

85 Eunotia flexuosa 155 7.2 12 90

86 Eunotia hemicyclus 50 5.7 9 12

87 Eunotia implicata 25 7.5 14 114

88 Eunotia incisa 210 6.8 11 41

89 Eunotia incisa var. 6 PIRLA 13 5.3 6 19

90 Eunotia intermedia 67 6.3 8 27

91 Eunotia itiarensis 39 6.3 7 16

92 Eunotia lapponica 10 4.9 8 34

93 Eunotia lunaris var. attenuata 102 6.3 12 51

94 Eunotia meisteri var. bidens 21 5.9 8 35

95 Eunotia meisteri 37 5.5 7 19

96 Eunotia microcephala 22 6.4 14 91

97 Eunotia monodon 94 7.3 14 104

98 Eunotia naegelii 65 6.7 16 125

99 Eunotia pectinalis var. minor 71 6.6 13 40

100 Eunotia pectinalis 86 6.7 10 46

101 Eunotia pectinalis var. ventricosa 162 7.1 17 140

102 Eunotia praerupta 62 6.8 10 29

103 Eunotia rhomboidea 120 6.1 9 24

104 Eunotia serra 38 5.8 11 39

105 Eunotia vanheurckii 82 6.5 9 30

106 Eunotia zasuminensis 58 6.9 11 54

107 Eunotia sp. 1 PIRLA 19 6.1 11 78

108 Eunotia sp. 2 PIRLA 33 6.4 10 55

109 Fragilaria acidobiontica 32 4.9 3 8

110 Fragilaria brevistriata 184 7.7 13 49

111 Fragilaria brevistriata var. capitata 52 7.7 10 61

112 Fragilaria capucina var. mesolepta 22 8.3 46 362

113 Fragilaria constricta 71 6.3 10 23

114 Fragilaria constricta f. stricta 19 7.7 12 221

115 Fragilaria construens var. binodis 72 7.4 9 32

116 Fragilaria construens 108 7.9 13 42

117 Fragilaria construens var. venter 48 7.3 8 15

118 Fragilaria crotonensis 149 8.0 14 194

119 Fragilaria hungarica var. tumida 49 5.7 18 25

120 Fragilaria lata 26 5.9 8 14

121 Fragilaria leptostauron 11 8.4 15 90

122 Fragilaria cf. oldenburgiana 78 6.2 6 18

123 Fragilaria pinnata var. acuminata 128 7.6 14 89

124 Fragilaria pinnata var. intercedens 19 8.3 18 72

125 Fragilaria pinnata var. lancettula 43 7.8 8 62

126 Fragilaria pinnata 241 7.6 14 57

127 Fragilaria vaucheriae 138 7.8 20 166

128 Fragilaria virescens var. exigua 172 7.0 9 37

129 Fragilaria virescens 46 6.9 14 38

130 Fragilaria sp. 2 PIRLA 31 8.2 21 89

131 Frustulia cf. magaliesmontana 81 5.5 6 13

132 Frustulia rhomboides 143 6.2 9 32

133 Frustulia rhomboides var. saxonica 204 6.1 9 22

134 Gomphonema acumenatum 72 7.6 14 54

135 Gomphonema angustatum 170 7.6 15 109

136 Gomphonema gracile 77 6.9 18 113

137 Gomphonema subtile var. sagitta 12 8.0 9 10

138 Gomphonema sp. 1 PIRLA 12 7.2 7 62

139 Gyrosigma acumenatum 43 8.2 27 65

140 Gyrosigma obscurum 10 8.0 21 690

141 Krasskela kriegeriana 20 7.4 10 35

142 Meridion circulare 32 8.0 14 104

143 Meridion circulare var. constricta 47 7.6 14 118

144 Navicula arvensis 72 7.2 14 69

145 Navicula bacillum 30 8.0 43 52

146 Navicula bremensis 46 6.2 7 13

147 Navicula cf. capitata 18 8.1 13 326

148 Navicula cocconeiformis 88 7.2 8 29

149 Navicula cryptocephala 62 8.1 23 104

150 Navicula cuspidata 26 8.1 53 329

151 Navicula disjuncta 82 7.5 12 64

152 Navicula explanata 36 7.7 11 33

153 Navicula globosa 24 8.1 10 41

154 Navicula gysingensis 48 7.4 18 105

155 Navicula halophila 16 8.4 12 465

156 Navicula cf. heimansii 124 6.6 8 23

157 Navicula laevissima 31 7.1 11 17

158 Navicula mediocris 100 6.5 10 23

159 Navicula minima 159 7.4 11 52

160 Navicula modica 113 7.7 14 36

161 Navicula mutica 29 7.6 11 120

162 Navicula pseudoscutiformis 89 7.3 9 34

163 Navicula pupula 220 7.5 13 41

164 Navicula pupula var. rectangularis 37 7.5 12 34

165 Navicula radiosa var. parva 171 7.8 16 43

166 Navicula radiosa 88 7.9 12 40

167 Navicula radiosa var. tenella 104 8.0 11 50

168 Navicula rhyncocephala 88 8.0 20 253

169 Navicula seminuloides 142 7.4 9 31

170 Navicula submolesta 56 7.3 12 161

171 Navicula subtilissima 88 6.4 10 17

172 Navicula tenuicephala 42 5.0 3 8

173 Navicula trivialis 12 8.1 33 147

174 Navicula vitiosa 167 7.4 11 38

175 Navicula vulpina 13 7.9 9 14

176 Navicula sp. 2 PIRLA 12 7.9 9 54

177 Navicula sp. 25 PIRLA 26 7.4 15 107

178 Neidium affine 145 6.0 9 14

179 Neidium bisulcatum 38 6.5 9 32

180 Neidium iridis var. amphigomphus 99 6.5 13 36

181 Neidium iridis var. ampliatum 10 7.1 11 20

182 Neidium iridis 95 6.9 13 38

183 Nitzschia acicularis 31 8.0 14 66

184 Nitzschia amphibia 17 8.1 19 80

185 Nitzschia angustata 18 7.7 15 163

186 Nitzschia denticula 26 8.1 7 70

187 Nitzschia dissipata 109 7.8 14 77

188 Nitzschia fonticola 83 7.7 11 20

189 Nitzschia gracilis 214 7.6 15 77

190 Nitzschia linearis 10 7.6 10 45

191 Nitzschia microcephala 12 7.4 8 22

192 Nitzschia palea 82 7.8 18 134

193 Nitzschia perminuta 35 7.3 12 45

194 Pinnularia abaujensis 103 6.7 11 25

195 Pinnularia abaujensis var. rostrata 24 7.3 14 13

196 Pinnularia abaujensis var. 2 PIRLA 77 6.1 7 10

197 Pinnularia biceps 116 6.8 10 19

198 Pinnularia borealis 15 7.8 30 154

199 Pinnularia braunii 69 6.7 12 41

200 Pinnularia hilseana 13 6.3 10 35

201 Pinnularia maior 22 7.0 15 47

202 Pinnularia mesolepta 34 7.1 10 22

203 Pinnularia microstauron 50 6.5 11 15

204 Pinnularia pogoii 37 6.2 14 20

205 Pinnularia polyonca 25 7.1 13 33

206 Pinnularia subcapitata 70 6.1 13 25

207 Pinnularia viridis 71 7.1 13 30

208 Pinnularia sp. 11 PIRLA 41 5.5 9 8

209 Stauroneis anceps 73 6.9 11 24

210 Stauroneis anceps f. gracilis 128 7.0 11 36

211 Stauroneis nobilis var. baconiana 36 7.4 11 44

212 Stauroneis phoenicenteron 144 7.3 14 38

213 Stenopterobia intermedia 151 6.4 8 23

214 Stephnodiscus hantzschii 16 8.4 34 540

215 Stephnodiscus niagrae 28 8.1 16 296

216 Stephnodiscus species 11 8.4 33 1036

217 Surirella delicatissima 129 5.8 7 14

218 Surirella linearis 80 7.2 19 37

219 Surirella sp. 2 PIRLA 17 7.0 3 122

220 Synedra acus 25 7.7 15 127

221 Synedra acus var. angustissima 30 8.0 22 110

222 Synedra delicatissima 72 7.8 9 85

223 Synedra famelica 99 7.7 13 170

224 Synedra filiformis var. exilis 37 7.5 9 75

225 Synedra parasitica 69 7.8 18 250

226 Synedra pulchella 24 7.9 48 683

227 Synedra rumpens var. familiaris 93 7.7 25 180

228 Synedra ulna 133 7.9 15 126

229 Tabellaria binalis 27 5.5 5 10

230 Tabellaria fenestrata 86 7.5 13 50

231 Tabellaria flocculosa var. linear 171 7.1 10 39

232 Tabellaria flocculosa strain III 229 7.0 9 43

233 Tabellaria flocculosa strain IIIp 236 7.2 8 50

234 Tabellaria flocculosa strain IV 205 6.8 9 38

235 Tabellaria quadriseptata 90 5.5 11 30

Note: Taxa listed here were present in at least 10 sites and had an abundance of 1% in at least one site.

No.	Taxon	No. of occurrences	Optima
pH	TP (µg/L)	Cl (µeq/L)
1	Achnanthes altaica	61	6.8	7	20
2	Achnanthes austriaca var. helvetica	175	7.1	10	57
3	Achnanthes bicapitata	53	7.4	10	69
4	Achnanthes clevei	12	8.1	7	244
5	Achnanthes detha	223	7.3	10	46

6	Achnanthes didyma	65	7.4	7	24
7	Achnanthes exigua	61	8.0	13	41
8	Achnanthes exigua var. hetrovelvata	15	7.8	11	85
9	Achnanthes flexella	70	7.5	9	28
10	Achnanthes hungarica	11	7.9	47	391

11	Achnanthes lanceolata	89	7.7	22	113
12	Achnanthes lanceolata var. rostrata	45	8.0	15	90
13	Achnanthes lapidosa	13	7.8	11	135
14	Achnanthes laterostrata	58	7.6	7	42
15	Achnanthes levanderi	36	7.2	8	58

16	Achnanthes linearis	164	7.6	12	53
17	Achnanthes marginulata	152	6.6	7	24
18	Achnanthes minutissima	292	7.8	13	105
19	Achnanthes peragalli	34	7.7	9	38
20	Achnanthes stewartii	14	7.5	12	152

21	Achnanthes suchlandtii	64	7.6	8	49
22	Actinella punctata	59	5.5	9	25
23	Amphora ovalis	123	8.0	22	118
24	Amphora perpusilla	30	8.3	25	592
25	Amphipleura pellucida	30	7.9	18	73

26	Anomoeoneis follis	22	6.9	9	13
27	Anomoeoneis serians var. brachysira	181	6.4	8	15
28	Anomoeoneis serians	50	5.5	6	14
29	Anomoeoneis vitrea	246	7.6	11	40
30	Asterionella formosa	209	7.6	10	128

31	Asterionella ralfsii var. americana (<45 µm)	13	5.3	21	38
32	Asterionella ralfsii var. americana (>45 µm)	135	5.8	11	24
33	Aulacoseira ambigua	241	7.5	14	89
34	Aulacoseira crassipunctata	16	5.5	23	68
35	Aulacoseira distans	169	6.6	8	24

36	Aulacoseira distans var. humilis	25	7.4	10	43
37	Aulacoseira distans var. nivalis	44	6.3	7	19
38	Aulacoseira distans var. nivaloides	109	6.9	11	28
39	Aulacoseira distans var. tenella	174	7.2	10	55
40	Aulacoseira granulata	24	7.8	29	241

41	Aulacoseira italica subsp. subarctica	75	7.5	8	70
42	Aulacoseira italica subsp. subarctica f. tenussima	13	7.9	11	180
43	Aulacoseira italica var. valida	30	7.4	13	47
44	Aulacoseira lirata f. biseriata	12	6.8	7	30
45	Aulacoseira lirata var. lacustris	43	6.5	9	19

46	Aulacoseira lirata	185	6.8	9	25
47	Aulacoseira nygaardii	100	6.5	10	21
48	Aulacoseira perglabra var. floriniae	79	6.6	7	27
49	Aulacoseira perglabra	39	6.0	5	10
50	Caloneis ventricosa	41	7.5	9	36

51	Cocconeis placentula	126	8.0	28	387
52	Cyclotella comta	200	7.4	6	44
53	Cyclotella meneghiniana	26	8.3	66	1113
54	Cyclotella michiganiana	120	8.0	9	142
55	Cyclotella ocellata	19	7.9	6	58

56	Cyclotella stelligera	285	7.3	7	59
57	Cymbella amphicephala v. hercynica	46	7.6	14	65
58	Cymbella cf. aequalis	95	7.7	12	19
59	Cymbella cesatii	55	7.8	10	19
60	Cymbella cistula	41	8.0	17	36

61	Cymbella cuspidata	53	7.4	13	35
62	Cymbella delicatula	25	8.1	8	120
63	Cymbella descripta	32	7.8	10	18
64	Cymbella cf. gaeumanii	58	6.6	8	29
65	Cymbella hebedrica	112	6.0	7	11

66	Cymbella lunata	141	7.0	9	24
67	Cymbella microcephala	135	7.9	11	34
68	Cymbella minuta f. latens	12	7.8	12	81
69	Cymbella minuta var. minuta	146	7.7	13	103
70	Cymbella minuta var. silesiaca	29	7.7	10	42

71	Cymbella cf. schubartii	36	6.5	12	21
72	Cymbella sp. 1 PIRLA	59	5.7	7	12
73	Diatoma hiemale var. mesodon	12	6.9	6	26
74	Diploneis marginestriata	62	7.7	11	56
75	Diploneis ovalis	44	7.8	10	98

76	Epithemia species	23	8.0	11	72
77	Eunotia bidentula	62	5.6	10	34
78	Eunotia bigibba var. pumila	13	5.9	10	18
79	Eunotia carolina var. 1 PIRLA	65	5.9	11	53
80	Eunotia curvata	172	6.1	9	24

81	Eunotia elegana	35	7.1	9	30
82	Eunotia exigua	127	5.9	10	20
83	Eunotia fallax	26	6.1	9	45
84	Eunotia flexuosa var. eurycephala	16	6.6	7	36
85	Eunotia flexuosa	155	7.2	12	90

86	Eunotia hemicyclus	50	5.7	9	12
87	Eunotia implicata	25	7.5	14	114
88	Eunotia incisa	210	6.8	11	41
89	Eunotia incisa var. 6 PIRLA	13	5.3	6	19
90	Eunotia intermedia	67	6.3	8	27

91	Eunotia itiarensis	39	6.3	7	16
92	Eunotia lapponica	10	4.9	8	34
93	Eunotia lunaris var. attenuata	102	6.3	12	51
94	Eunotia meisteri var. bidens	21	5.9	8	35
95	Eunotia meisteri	37	5.5	7	19

96	Eunotia microcephala	22	6.4	14	91
97	Eunotia monodon	94	7.3	14	104
98	Eunotia naegelii	65	6.7	16	125
99	Eunotia pectinalis var. minor	71	6.6	13	40
100	Eunotia pectinalis	86	6.7	10	46

101	Eunotia pectinalis var. ventricosa	162	7.1	17	140
102	Eunotia praerupta	62	6.8	10	29
103	Eunotia rhomboidea	120	6.1	9	24
104	Eunotia serra	38	5.8	11	39
105	Eunotia vanheurckii	82	6.5	9	30

106	Eunotia zasuminensis	58	6.9	11	54
107	Eunotia sp. 1 PIRLA	19	6.1	11	78
108	Eunotia sp. 2 PIRLA	33	6.4	10	55
109	Fragilaria acidobiontica	32	4.9	3	8
110	Fragilaria brevistriata	184	7.7	13	49

111	Fragilaria brevistriata var. capitata	52	7.7	10	61
112	Fragilaria capucina var. mesolepta	22	8.3	46	362
113	Fragilaria constricta	71	6.3	10	23
114	Fragilaria constricta f. stricta	19	7.7	12	221
115	Fragilaria construens var. binodis	72	7.4	9	32

116	Fragilaria construens	108	7.9	13	42
117	Fragilaria construens var. venter	48	7.3	8	15
118	Fragilaria crotonensis	149	8.0	14	194
119	Fragilaria hungarica var. tumida	49	5.7	18	25
120	Fragilaria lata	26	5.9	8	14

121	Fragilaria leptostauron	11	8.4	15	90
122	Fragilaria cf. oldenburgiana	78	6.2	6	18
123	Fragilaria pinnata var. acuminata	128	7.6	14	89
124	Fragilaria pinnata var. intercedens	19	8.3	18	72
125	Fragilaria pinnata var. lancettula	43	7.8	8	62

126	Fragilaria pinnata	241	7.6	14	57
127	Fragilaria vaucheriae	138	7.8	20	166
128	Fragilaria virescens var. exigua	172	7.0	9	37
129	Fragilaria virescens	46	6.9	14	38
130	Fragilaria sp. 2 PIRLA	31	8.2	21	89

131	Frustulia cf. magaliesmontana	81	5.5	6	13
132	Frustulia rhomboides	143	6.2	9	32
133	Frustulia rhomboides var. saxonica	204	6.1	9	22
134	Gomphonema acumenatum	72	7.6	14	54
135	Gomphonema angustatum	170	7.6	15	109

136	Gomphonema gracile	77	6.9	18	113
137	Gomphonema subtile var. sagitta	12	8.0	9	10
138	Gomphonema sp. 1 PIRLA	12	7.2	7	62
139	Gyrosigma acumenatum	43	8.2	27	65
140	Gyrosigma obscurum	10	8.0	21	690

141	Krasskela kriegeriana	20	7.4	10	35
142	Meridion circulare	32	8.0	14	104
143	Meridion circulare var. constricta	47	7.6	14	118
144	Navicula arvensis	72	7.2	14	69
145	Navicula bacillum	30	8.0	43	52

146	Navicula bremensis	46	6.2	7	13
147	Navicula cf. capitata	18	8.1	13	326
148	Navicula cocconeiformis	88	7.2	8	29
149	Navicula cryptocephala	62	8.1	23	104
150	Navicula cuspidata	26	8.1	53	329

151	Navicula disjuncta	82	7.5	12	64
152	Navicula explanata	36	7.7	11	33
153	Navicula globosa	24	8.1	10	41
154	Navicula gysingensis	48	7.4	18	105
155	Navicula halophila	16	8.4	12	465

156	Navicula cf. heimansii	124	6.6	8	23
157	Navicula laevissima	31	7.1	11	17
158	Navicula mediocris	100	6.5	10	23
159	Navicula minima	159	7.4	11	52
160	Navicula modica	113	7.7	14	36

161	Navicula mutica	29	7.6	11	120
162	Navicula pseudoscutiformis	89	7.3	9	34
163	Navicula pupula	220	7.5	13	41
164	Navicula pupula var. rectangularis	37	7.5	12	34
165	Navicula radiosa var. parva	171	7.8	16	43

166	Navicula radiosa	88	7.9	12	40
167	Navicula radiosa var. tenella	104	8.0	11	50
168	Navicula rhyncocephala	88	8.0	20	253
169	Navicula seminuloides	142	7.4	9	31
170	Navicula submolesta	56	7.3	12	161

171	Navicula subtilissima	88	6.4	10	17
172	Navicula tenuicephala	42	5.0	3	8
173	Navicula trivialis	12	8.1	33	147
174	Navicula vitiosa	167	7.4	11	38
175	Navicula vulpina	13	7.9	9	14

176	Navicula sp. 2 PIRLA	12	7.9	9	54
177	Navicula sp. 25 PIRLA	26	7.4	15	107
178	Neidium affine	145	6.0	9	14
179	Neidium bisulcatum	38	6.5	9	32
180	Neidium iridis var. amphigomphus	99	6.5	13	36

181	Neidium iridis var. ampliatum	10	7.1	11	20
182	Neidium iridis	95	6.9	13	38
183	Nitzschia acicularis	31	8.0	14	66
184	Nitzschia amphibia	17	8.1	19	80
185	Nitzschia angustata	18	7.7	15	163

186	Nitzschia denticula	26	8.1	7	70
187	Nitzschia dissipata	109	7.8	14	77
188	Nitzschia fonticola	83	7.7	11	20
189	Nitzschia gracilis	214	7.6	15	77
190	Nitzschia linearis	10	7.6	10	45

191	Nitzschia microcephala	12	7.4	8	22
192	Nitzschia palea	82	7.8	18	134
193	Nitzschia perminuta	35	7.3	12	45
194	Pinnularia abaujensis	103	6.7	11	25
195	Pinnularia abaujensis var. rostrata	24	7.3	14	13

196	Pinnularia abaujensis var. 2 PIRLA	77	6.1	7	10
197	Pinnularia biceps	116	6.8	10	19
198	Pinnularia borealis	15	7.8	30	154
199	Pinnularia braunii	69	6.7	12	41
200	Pinnularia hilseana	13	6.3	10	35

201	Pinnularia maior	22	7.0	15	47
202	Pinnularia mesolepta	34	7.1	10	22
203	Pinnularia microstauron	50	6.5	11	15
204	Pinnularia pogoii	37	6.2	14	20
205	Pinnularia polyonca	25	7.1	13	33

206	Pinnularia subcapitata	70	6.1	13	25
207	Pinnularia viridis	71	7.1	13	30
208	Pinnularia sp. 11 PIRLA	41	5.5	9	8
209	Stauroneis anceps	73	6.9	11	24
210	Stauroneis anceps f. gracilis	128	7.0	11	36

211	Stauroneis nobilis var. baconiana	36	7.4	11	44
212	Stauroneis phoenicenteron	144	7.3	14	38
213	Stenopterobia intermedia	151	6.4	8	23
214	Stephnodiscus hantzschii	16	8.4	34	540
215	Stephnodiscus niagrae	28	8.1	16	296

216	Stephnodiscus species	11	8.4	33	1036
217	Surirella delicatissima	129	5.8	7	14
218	Surirella linearis	80	7.2	19	37
219	Surirella sp. 2 PIRLA	17	7.0	3	122
220	Synedra acus	25	7.7	15	127

221	Synedra acus var. angustissima	30	8.0	22	110
222	Synedra delicatissima	72	7.8	9	85
223	Synedra famelica	99	7.7	13	170
224	Synedra filiformis var. exilis	37	7.5	9	75
225	Synedra parasitica	69	7.8	18	250

226	Synedra pulchella	24	7.9	48	683
227	Synedra rumpens var. familiaris	93	7.7	25	180
228	Synedra ulna	133	7.9	15	126
229	Tabellaria binalis	27	5.5	5	10
230	Tabellaria fenestrata	86	7.5	13	50

231	Tabellaria flocculosa var. linear	171	7.1	10	39
232	Tabellaria flocculosa strain III	229	7.0	9	43
233	Tabellaria flocculosa strain IIIp	236	7.2	8	50
234	Tabellaria flocculosa strain IV	205	6.8	9	38
235	Tabellaria quadriseptata	90	5.5	11	30

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