TABLE 1.

Summary of the relevant parameters characterizing the six major groups of freshwater habitats studieda

Habitat typenbElevation (m above sea level)Area (ha)pHConductivity (μS cm−1)A250/A365O2 concn (mg liter−1)DOC concn (mg liter−1)cA254/DOCcChl-a concn (μg liter−1)dConcn of bacteria (106 cells ml−1)
Humic lakes and ponds281,355 ± 470 (465-1,950)0.5 ± 1.5 (0.0002-6.5)4.9 ± 0.5 (3.9-5.9)22 ± 23 (4-69)4.8 ± 0.6 (3.2-6.7)9.2 ± 2.3 (4.6-18)11.2 ± 8.9 (5.3-37.7)3.62 ± 0.88 (1.55-5.24)6.6 ± 5.6 (1.4-14.9)2.76 ± 2.26 (0.41-11.5)
Acidified lakes41,053 ± 42 (1,007-1,090)13.9 ± 11.4 (5.5-30.6)4.6 ± 0.2 (4.6-5.0)19 ± 4 (14-22)7.5 ± 2.4 (5.6-11)15.0 ± 0.8 (14.2-16)4.9 ± 1.6 (2.9-7.0)2.41 ± 0.88 (1.18-3.26)4.9 ± 2.9 (2.5-8.8)0.60 ± 0.37 (0.20-1.10)
Forest ponds11803 ± 34 (770-885)2.2 ± 1.9 (0.2-5.1)6.6 ± 0.4 (6.0-7.2)55 ± 13 (41-82)4.7 ± 0.2 (4.2-5.1)10.7 ± 1.3 (7.7-12.3)5.9 ± 1.2 (4.4-7.9)4.41 ± 0.37 (4.09-5.39)3.4 ± 2.2 (1.1-8.5)2.18 ± 1.11 (0.99-4.26)
Small shallow ponds111,223 ± 598 (486-1,950)0.18 ± 0.57 (0.001-1.91)6.7 ± 0.7 (5.6-7.6)171 ± 202 (6-493)5.1 ± 0.8 (3.5-6.3)5.9 ± 3.0 (0.7-8.9)5.2 ± 2.9 (2.5-12.7)2.53 ± 1.09 (0.51-4.08)NDe4.53 ± 4.16 (0.85-13.1)
Alkaline lakes44815 ± 475 (422-2,309)596 ± 1,221 (1-4,620)8.2 ± 0.4 (6.6-8.6)235 ± 93 (17-449)7.0 ± 2.3 (3.2-15.5)9.2 ± 1.1 (7.6-14.2)2.6 ± 0.7 (1.7-3.6)1.83 ± 0.79 (0.77-2.85)2.7 ± 2.9 (1.0-9.7)1.93 ± 1.13 (0.41-5.07)
Fishponds and reservoirs24641 ± 113 (250-810)31 ± 63 (0.1-206)7.3 ± 0.9 (6.1-9.1)210 ± 193 (60-918)5.8 ± 1.6 (3.4-10.1)10.2 ± 3.8 (4.2-21.1)6.9 ± 3.2 (1.7-12.9)2.57 ± 0.96 (0.83-4.40)21.6 ± 31.5 (1.0-122.5)5.56 ± 4.37 (1.64-20.1)
  • a The values are means ± standard deviations (ranges).

  • b n indicates the number of measurements.

  • c The DOC concentration was directly measured only in the habitats sampled during 2008; for the habitats sampled during 2006 and 2007 the DOC concentration was estimated from its tight correlation with the A250.

  • d Chl-a concentrations in humic lakes and ponds and Austrian lakes were determined only in 2008 (for details see Materials and Methods and Table S1 in the supplemental material).

  • e ND, not determined.