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138 J. E. Brittain period was longer and insect numbers higher, life-cycle data could be obtained. With only one, or even two, sampling visits, some major species could quite easily be absent from collections. For example, the mayfly Baetis macnni only occurs in collections from the end of July to the end of September while the stonefly Cnfinia atra is absent from collections for several weeks during the summer. The greater part of the field work was carried out during 1971, biit in certain localities some sampling was carried out during 1972, largely to obtain more detailed information on the life cycles of certain species. As a large number of localities, often some distance from the road, were sampled with such a frequency, it was necessary to employ a relatively simple and rapid method. In addition, variation in substratum in the littoral and the difficulties of sampling substrata composed of large stones imposed limitations. However. the same methods were used throughout the study, thus making the results comparable within the scope of the investi- ., Two main types of sampling were used in each locality. First, for a period of 5 minutes, stones were picked up from the bottom by hand and examined for Ephemeroptera and Plecoptera. At the same time as the stones were picked up a net was held underneath to obtain those nymphs that swam away when disturbed (Macan & Maudsley 1968). Secondly, a 'kick' method was used, modified from its use in running-water studies (Hynes 1961, Frost et al. 1971), whereby the substratum was disturbed by kicking and a net passed once over the area. A total of five kicks was made. In some of the more productive lakes, where littoral vegetation was abundant, five net sweeps were made through the vegetation (Macan 1964). The net used in the investigations was circular, with a diameter of 20 cm and nettinp with 15 mesheslcm. With " the exception of the largest and most varied localities where three stations were taken, two stations were sampled in each locality on each sampling visit. Stations were chosen to be representative of that locality and were sited away from inflow and outflow streams as such areas were considered to have a different fauna1 coinposition. A search for aduits was made in the vicinity of each station, but species only found as adults are indicated in Tables 1-IV by 'I', there being the ~ossibilit~ that they did not originate from the habitat in question. Nymphal collections were preserved in 3 O10 formalin, and adult specimens initially in 70 O10 alcohol and subsequently in 3 O/o formalin. The body lengths of the nymphs were measured, to the nearest 0.03 mm, from the tip of the head to the base of the cerci. At each station air and water temperatures were measured. Water temperature was measured in the littoral zone at a depth of approximately 20 cm. To determine whether these spot temperature readings were representative of the maximum tem~eratures reached, maximiim-minimum thermometers were placed in eight localities during the siimmer of 1971. The presence and extent of ice cover was also noted and the ice-free period given in the results is a composite value-based on the conditions of 1971-1973. A water sample for subsequent chemical analysis was taken from the shallow littoral in every locality on each sampling occasion. Calcium and magnesium values were obtained by titration with E.D.T.A. (the Schwarzenbach method). Specific conductivity was determined using a Philips direct-reading conductivity meter and values given as kmhos at 18OC (x,,) while pH was measured by a Radiometer pH meter 26. The consumption of KMnO, was determined as described by Werescagin (1931). For the chemical parameters mean values for the whole ice-free ~eriod were determined for each localitv and it is these values tliat are given in the results tables. From the summation of the results of the two methods of sampling the nymphal populations, an abundance index was calculated for al1 the species in each locality. In view of the variation in life cycle, whereby some species were present throughout the ice-free period while others occurred only briefly, maximum abundance rather than mean abundance formed the basis of the index. The abundance index for a locality was the maximum number of specimens of that species taken on any single sampling occasion divided by the number of sampling stations. Actual values ranged " from 0.1 to 246. To simplify the appreciation of the relative abundance between localities. and as the methods are subject to a cerkin amount of
Ephemeroptera and Plecoptera 139 Table 1. Physical, chemical and faunistic parameters of the investigated localities in the Finse area Ephem. Plecoptera .- C. 1. Flakavatn 1448 2. Lake 1430 1430 3. Lake 6 1365 4. Lake 5 1363 5. Lake 4 1353 6. Lake 8 1330 7. Sandaavatn 1262 8. Lake 13 1225 9. Finsevatn 1214 variation, the indices were grouped into the following four categories: ability of glaial material to absorb H+ions (Str~m 1956). The KMn04 consumption is extremely low with the exception of Lake 13, 0.1-0.9 + rare which is partly surrounded by peat bog and 1.0-9.9 + + common has a small catchment area. 10.0-99.0 -+ + + moderately abundant The fauna of lentic localities at Finse is >lo0 ++++ abundant poor in species, particularly Ephemeroptera. DISTRIBUTION AND ABUNDANCE Finse A summary of the results from the Finse area is given in Table 1. During the summer of 1971 the highest temperatures recorded by maximum-minimum thermometers in place throughout the ice-free period in Lake 8 and Sandaavatn were 13.7OC and 8.8OC respectively. Spot values from other localities reinforce this view, with spot maximum temperatures ranging from 5.2' C for Flakavatn to 10.0' C for Lake 8. The ice-free period for the lakes in the Finse area is correspondingly short, between 3 and 4 months. The concentration of dissolved minerals shows considerable variation, with particularly high values in areas of recent glacial activity such as Lakes 4, 5, and 6 which show increasing specific conductivity with decrease in distance from the glacier front of Bliisen. Values of pH range from 6.7 to 7.4, the higher values again being found near Bliisen. The high pH values are due to the Only two species of Ephemeroptera are present. BaZtis macani Kimmins and Sibhlonurus lacustris Eton. The former occurs up to over 1300 m and is often abundant in outlet streams. iFnsevatn is the sole lentic habitat in which S. lacustris has been found, conditions probably being too severe in the other localities. However, S. lacustris has been found recently in trout from Lengjedalsvatn (7 km east of Finse), situated 1305 m above sea leve1 (Lien, personal communication), so altitude in itself is not limiting. Both species are aestival forms, growing rapidly during the course of the summer and emerging at the end of the summer. The dominant and often the sole species of Plecoptera is Capnia atra Morton, which occurs even in the most extreme habitats such as Flakavatn and Lake 1430. Also it has the capacity to invade relatively recently created habitats such as Lake 6 which was covered by glacier until about 1920 (Andersen & Sollid 1971). Investigation of a small lake near Bliisen. , ex~osed onlv since 1955. indicated L that C. atra was absent, probably owing to the lack of suitable substratum rather than
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Microrespirometer 189 termination o
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192 F. E. Klallsen The specimens fr
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194 F. E. Klausen REFERENCES Ardii,
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196 A. Lillehammer present in Norwa
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198 A. Lillehammer Results The numb
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202 A. Lillehammer parts of the are
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204 A. Lillehammer carnivorous spec
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Table IV. Species distribution, in
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212 A. Lillehammer Blatjemn Diura b
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Table VII. Species distribution in
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Z 0 ...... ~ '"s' '" ~ .... '.xl ~
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Table IX. Species distribution in s
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220 A. Lillehammer same latitude as
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222 A. Lillehammer Table XI. The pH
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224 A. Lillehammer These species se
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226 A. Lillehammer Table XVI. The s
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228 A. Lillehammer Fig. 22. Stream
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238 A. Lillehammer high altitude la
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244 A. Lillehammer streams and rive
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246 A. Lillehammer Blies (1953, 195
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248 A. Lillehammer streams are to a
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250 A. Lillehammer Muller, K. 1955.
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252 Bokanmeldelser produserende, en
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N orsk Entomologisk Tidsskrift Norw
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