Comparison of rhizopod associations

Abstract

HOOGENRAAD (1935) has given a survey of the rhizopad associations of several Sphagnetae of the Netherlands and a comparison with some populations from diverse localities in Europe, He based his analysis upon the three types distinguished by HARNISCH (1929) 3. Nebela carinata proved not to be restricted to one of HARNISCH's types but can be found in all three types; the absence in many associations is probably connected with its dependence of the humidity of the medium; it can be expected only in constantly wet Sphagnum.~ address: Bur. Weertstraat 87-1, 6814 HN Amhem, The Netherlands.For a comparison of the environmental conditions of our Dutch samples with samples of alpine we studied samples from Norway, Austria and Switzerland, collected from small bogs lying at the slopes of mountains and hills. Nebela tubulosa, Nebula marginata, Amphitrema flavum and Assulina scandinavica could be found in most of them. These species are rare in the Netherlands: Nebela tubulosa and Assulina scandinavica were found twice and Nebela marginata is known from three Iocalitlas.Looking at the difference between the lowland and the alpine Sphagnum deposits one gets the impression that the differences in the populations can be ascribed to the process of purification of the water. In the stagnant lowland pools the water is supplied by rain or the soil, interrupted by periods of dryness and concentration, while the alpine slopes have a constant supply from above and a renewal by flowing down. The Dutch localities, where I found the above mentioned alpine species, presented nearly the same circumstances: water flowing in from diluvial sands and flowing down to lower levels. These delicate differences in the water supply may be responsible for the presence or absence of some sensitive species in otherwise similar associations. A somewhat similar situation is presented by Nebela barbata and Nebela speciosa. Nebela barbata with a widespread geografical distribution (Eurasia, America, Indonesia) is a rather rare component among the characteristic sphagnicol associations and so it was surprising to observe Nebela speciosa (known from Europa and America) in an Amphitrema flavum association from te lake "Botshol".A more subtle analysis of these little differences between greatly similar associations may be obtained by the investigation of the presence of e.g. Desmidiaceae, which are also very sensitive to environmental conditions (pH, 02, chemistry, humidity).Recently, MEISTERFELD (1977) published a survey of his intensive investigations on the diverse environmental conditions, which are likely crucial for the presence and 50

Modelling hydrological relationships of testate amoebae (Protozoa: Rhizopoda) on New Zealand peatlands

“…It is notable that the most extreme deviant sample came from a site affected by A surprising feature of the species data is the number of species in common with peatland faunas in the Northern Hemisphere. This cosmopolitanism has been commented on before but the proportion of the fauna which is found in both New Zealand and northern peatlands is still more than would have been expected (Hoogenraad & de Groot 1979). As a result the individual species optima can be compared with those reported from similar studies on northern peatlands.…”