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Home , Chilodonella uncinata, Chilomonas, Goniomonas, Holotricha, Hypotrich, Katablepharis

Limnologica 29 (1999)407424 LIMNOLOGICA http://www.urbanfiscber.de/j ournals/limno © by Urban & Fischer Verlag

1) Institut ftir Zoologie der Freien Universitiit Berlin, AG Protozoologie, Berlin, Germany; 2) Institut ftir 0kologie der Friedrich-Schiller-Universit~it Jena, AG Limnologie, Jena, Germany

Periphyton and Sphagnicolous of Dystrophic Bog Lakes (Brandenburg, Germany) II. Characteristic and Trophy of the Lakes

MICHAELA C. STRUDER-KYPKE 1) • WILFRIED SCHONBORN 2)

With 8 Figures and one Table

Key words: Bog lakes; artificial substrates; ; ; testate amoebae; eutrophication

Abstract

Glass-slides were exposed in tour different bog lakes located in great Weichselian stage of the last glaciation and deposited in the forest areas in Northern Germany, about 100 km north of Berlin, in glacial drift or outwash plain. Those ice blocks often took order to examine the community of these dystrophic, acid several hundred years to melt completely, finally resulting lakes. Species composition and succession of the periphyton were in the formation of kettle lakes (Fig. 1). About 11,000 years studied during one year. The four investigated bog lakes exhibit simi- ago, the paludification began and mesotrophic-subneutral lar species compositions, most of the species were present in each of the four lakes. The periphyton was composed of a great variety of pro- circumstances prevailed. This process stopped approximate- tist species. Specimens of all major flagellated protists and of most of ly 9,000 years ago. The ice blocks were melted, the climate the taxa were found on the slides. Many of these species are changed and it became dry and warmer. Approximately ubiquitous. Some species, however, like the flagellates Spongomonas 4,000-2,000 years ago, a secondary turf layer started to sacculus, Rhipidodendron huxIeyi, Cyathobodo sp., and Pseudoden- grow on these paludificated lakes. Water was supplied only dromonas vlkii as well as the ciliates Ophrydium hyaIinum, Lep- by precipitation and the run-off from surrounding land topharynx costatus, Uroleptus caudatus, and Platyophrya sphagni are (CASPER & SCHEFFLER 1990; SUCCOW 1987; SUCCOW & found more frequently in acid waters. A regular and common occur- JESCHKE 1990). rence of these species partly characterizes the acid Sphagnum bogs. The larger bogs possess a residual lake which shows al- Besides that, common species like Bodo spp., spp., Go- most no further terrestrialization, but reveals the excess niomonas truncata, , sp., and Cyr- tolophosis mucicola are represented in the periphyton. Examinations water of the bog. Its edges are surrounded by Sphagnum of the testate amoebae in the Sphagnum mats show a very different mats that regularly tear off. In the center, kettle hole bogs are species composition compared to earlier studies. oligotrophic. The bog is surrounded by laggs (small water- The investigated bog lakes revealed mesotrophic conditions. In filled ditches) which collect the run-off water and are more the upper regions of the Sphagnum mats and in the center of the larg- mesotrophic (StJccow & JESCHKE 1990). er bog lakes, oligotrophic conditions still prevail. The lower regions With exception of the testate amoebae, protists of bogs of the Sphagnum mat and the smaller lakes, however, are influenced have always been neglegted in studies dealing with this habi- by the partly degradation of plants and the run-off water from sur- tat (e.g. HARNISCH 1925, 1929). Only few investigations rounding land. In comparison to earlier studies, the species composi- were carried out concerning the protist community of acid tion indicates a beginning eutrophication of the bog lakes. A direct anthropogenic impact can be excluded. bog lakes. The flagellates of bogs have not been examined or presented in detail up to now. SKUJA'S works (1948, 1956, 1964) described many planktonic flagellates, but from acid Introduction lakes. The ciliates of acid bogs were comprehensively stud- ied and many new species were described by GROLII~RE The bog lakes were formed by the melting of ice blocks (1975a, 1975b, 1977a, 1977b, 1978) and WENZEL (1953). which were broken from the withdrawing glaciers of the Besides that, only older literature exists about this habitat

0075-9511/99/29/04-407 $ 12.00/0 407 ~ 15,000 b. Chr. Deposited ice blocks in the glacial drift

~ 11,000 b. Chr. (late glacial) Melting of the ice blocks and formation of kettle lakes, begin of the paludification

8,000 b. Chr. (post glacial) End of the paludification i- and temporary stagnation in the peat formation

Fig. 1. Development of the bog lakes (after JESCHKE 1987).

(e.g. LEVANDER 1900; MERMOD 1914; SCHLENKER 1908; Material and Methods THIEBAUD &; FAVRE 1906). Testate amoebae are named tyrphobionts or sphagno- Sampling bionts and are considered as characteristic of The sampling of the periphyton with glass slides as artificial sub- bogs. Therefore, extensive studies exist concerning their dis- strates according to WmBERT(1969) was performed as described in tribution, zoning, , and systematics (e.g. HARNISCH STRI~DER-KYPKE(1999, this volume). Also the live counting of the 1925, 1927, 1929; MEISTERFELD 1977, 1979a, 1979b; protists is decribed there in detail. SCHONBORN 1962a, 1962b, 1963, 1990). Each region of the The sampling and counting of the testate amoebae of the Sphag- Sphagnum mats comprises its own community of testate num mats were done as described by SCn0NBORN(1963). To differ- amoebae. The horizontal distribution of these protists de- entiate the communities of the upper and lower horizons, the Sphag- pends on the degree of humidity; the vertical zoning is de- num cushion was cut - starting from the surface - into short pieces pendent on the light impact and the trophy (SCHONBORN of approximately 1 cm length and examined separately. 1962b, 1963). Characteristic genera of testate amoebae with- in the wet Sphagnum are: Hyalosphenia, Difflugia, Arcella, Light microscopy Centropyxis, Nebela, Euglypha, and Heleopera. The species Hyalosphenia papilio, Amphitrema flavum, A. stenostoma, Species determination was performed by means of an Axiophot mi- croscope with high magnification and - if necessary - with phase Heleopera sphagni, and Placocista spinosa harbour zoo- contrast or differential interference contrast. Additionally, protargol chlorellae and are very sensitive indicators for oligotrophic impregnation of whole slides was carried out in order to confirm conditions (ScHONBORN 1963). Reasons why the group of species determinations of the ciliates. testate amoebae in general are typical bog inhabitors, are the Species determination was made mainly with the help of the fol- relative low competitive pressure with other protists and the lowing literature: oligotrophic conditions in bogs (GOTTLICH 1990; SCHON- Flagellates: ETTL (1983), ETTL & GARTNER (1988), HUBER- BORN 1962a, 1962b). PESTALOZZI (1941, 1955, 1968), PATTERSON & LARSEN (1991), Our study deals with the species composition of the bog POPOVSKY & PFIESTER(1990), SKUJA(1948, 1956, 1964), and STAR- lakes, with main emphasis on the periphyton in the Sphag- MACH (1985). Ciliates: FOISSNERet al. (1991, 1992, 1994, 1995), KAnL(1930, num mat. Indicator species of acid, dystrophic lakes are fig- 1931, 1932, 1935). ured out and the environmental conditions (especially the trophy) of the lakes are compared to earlier studies (SCHON- BORN et al. 1965) and discussed. Protargol impregnation of whole slides The investigated bog lakes Himmelreichsee, Teufels-See, The protargol staining of the exposed slides followed the procedure Groger Barschsee and Kleiner Barschsee were described in described by WILBERT (1976). The cells were fixed in vapour of a detail in STRODER-KYPKE (1999, this volume), showing the 2% aqueous solution of Osmium tetroxide for 1-2 minutes. Subse- seasonal changes in the periphyton community and the peri- quently the liquid remaining on the slides was mixed with a drop of phyton structures of different habitats within the lakes. egg-albumen and the slides were allowed to dry at room temperature

408 Limnologica 29 (1999) 4 for 24 hours. The periphyton was post-fixed in Bouin's solution for sulfate solution for 1-2 minutes. After a last washing step in running 25 minutes and then transferred to 70% ethanol for 20 minutes, in tap water for 5 minutes, the slides were dehydrated in ethanol series order to remove the fixative. At this stage, the staining can be inter- (30, 50, 70, 95, 100%) with Xylene as final medium (5 minutes each) rupted, e. g. to collect the slides of several sampling dates. The slides and mounted with Entellan (Fa. Merck, Darmstadt). were washed for 5 minutes in running tap water. Subsequently, oxi- dation in a 5% Potassiumpermanganate solution for 1-2 seconds, fol- lowed by bleaching with 5% oxalic acid, also for 1-2 seconds, took place. Both steps were followed by a 10 minute washing step in run- Results and Discussion ning tap water. Then the slides were rinsed in Aqua dest. and placed in a 0.5% Protargol solution (= Albumosesilver of the Fa. Fluka, Species list of the flagellates and ciliates in Buchs/Switzerland) for 45 minutes at 45-50 °C. After this impregna- the four bog lakes tion, the slides were rinsed in Aqua dest. and transferred into a 1% Hydroquinone solution for 5 minutes. The slides were washed for 10 In Table 1 all species of flagellates and ciliates are listed minutes in running tap water and finally fixed in a 5% Sodiumthio- which were found in the lakes during the investigations from

Table 1. Species list of the flagellates, ciliates and rhizopods of the periphyton and Sphagnum of the bog lakes in alphabetical order. Abbreviations: Bio - Biocoenosis; H/A - Lake Himmelreichsee, site A; H/B - Lake Himmelreichsee, site B; T - Lake Teufels-See; G/A - Lake Groger Barschsee, site A; G/B - Lake GroBer Barschsee, site B; K - Lake Kleiner Barschsee; uh - upper horizon; lh - lower horizon; As - Aufwuchs, sessile; Av - Aufwuchs, vagile; P - Plankton; o - single; + - rare (testate amoebae: present); ++ - regularly observed (testate amoebae: dominant); +++ - nearly always present. Characteristic species of the different sampling sites are emphasized by bold symbols.

Species Bio H/A H/B T G/A G/B K

FLAGELLATES elenkinii P o + + ++ + ++ Anisonema acinus Av + + + + + Astasia sp. Av + + + + + + Bicosoeca lacustris As + + + + + + Bodo designis Av ++ ++ ++ ++ ++ + Bodo globosus Av + + + ++ +++ ++ Bodo saltans Av ++ ++ ++ ++ ++ ++ Bodo sp. Av + + + + + 0 Carteria sp. Av ++ ++ ++ +++ +++ ++ paramaecium P + + 0 Chlamydomonas costata P + + + + + + Chlamydomonas sphagnophila P + + + + ++ + Chlamydomonas sp. Av +++ ++ ++ +++ +++ ++ ChloJvgonium fusiforme P + o + + ++ Chloromonas angustissima P ++ + + ++ + + Chloromonas sp. P + + + + + +++ Chrysamoeba sp. As + o o + Cladomonasfi'uticulosa As o + o ++ + o ClTptomonas borealis P + + + + Cryptomonas erosa P + + o + + o Cryptomonas marssonii P + + + + + ++ Cryptomonas obovata P + + + + + + Cryptomonas ovata P ++ ++ ++ +++ +++ ++ Cryptomonas platyuris P + + + + 0 o Cyathobodo sp. As + + + + + + Cystodinium sp. As +++ +++ o + + Dinobryon pediforme P + + Dinobryon sertularia P + + ++ ++ + Entosiphon sulcatum Av + + + + + + acus Av o + + + ++ + Euglena proxima P + + + + + + Euglena sp. Av + o + ++ ++ + Glenodiniopsis steinii P + + + + + truncata Av ++ ++ + + ++ + Gonyostomum semen Av + + + 0 + fi~scum P o + 0 Gymnodinium helveticum P o 0 Gymnodinium lantzschii P + + o + + Gymnodinium triceratium P o o + +

Limnologica 29 (1999) 4 409 Table 1. (Continued).

Species Bio H/A H/B T G/A G/B K

Gymnodinium uberrimum P ++ ++ ++ + + + Gymnodinium sp. P o o + o + + Hemidinium nasutum P o o + Heterochromonas sp. P + + + + ++ + velifera As + + + + + + Kathablepharis obIonga P + + + + ++ + Kathablepharis ovalis P + + + + ++ + LepochTvmulina calyx As + + + + Lepocinclis ovum Av + o + + + Mallomonas sp. P o + + Menoidium sp. P o o Monochrysis hyalina P + + + + o + Ochtvmonas oligochrysis As + + ++ ++ + + Ochromonas sp. P o o + Parmidium circulare P + o ++ + + + Peranema sp. Av o o o o + + umbonatum P + + o + + +++ Peridinium willei P + + + + o Petalomonas sp. Av+ o o Phacus longicaudis P o Polytoma sp. P + + + + + + Polytomella sp. P o Poteriochromonas nutans As + + + + + P~vtaspis sp. Av + + + + + + Protetvspongia lackeyi As ++ + + o + Pseudodendromonas vlkii As + + + + Rhipidodendron huxleyi As +++ ++ ++ +++ + Rhynchomonas nasuta Av o + + + Salpingoeca buetschlii As +++ ++ ++ ++ + ++ Salpingoeca clarkii As +++ ++ ++ ++ + ++ Sphaeroeca volvox As + + + + + + Sphenomonas quadrangularis Av o o + + o Spongomonas sacculus As +++ +++ ++ +++ + ++ Synura echinulata P + + + + + o Synura sphagnicola P + + + + + o

CILIATES Aspidisca spp. Av + + + ++ ++ + (A. turrita and A. lynceus) Bryophyllum sp. Av + ++ + + + Calyptotricha sp. As 0 Chilodonella uncinata Av +++ +++ +++ ++ ++ +++ Cinetochilum margaritaceum Av ++ ++ + 0 + Colpidium kleini Av o o + + + Cyclidium muscorum P + + 0 + ++ Cyrtolophosis sp. Av + + + + +++ + Cyrtolophosis mucicola Av + + ++ ++ anser Av 0 Enchelyodon sp. Av + + o + + + sp. As o o Gastronauta membranaceus Av + ++ + + Glaucoma scintillans P/Av + o 0 Holophrya sp. P + + + + + + Lembadion lucens P/Av + + + ++ ++ 0 Lepwpharynx costatus Av ++ ++ ++ ++ ++ ++ Litonotus lamella Av + + + + + + Litonotus triqueter Av + o + 0 + Loxophyllum sp. Av + + + + + + Metacineta micraster As o 0 0 + Microdiaphanosoma arcuatum Av + + + + ++ + Microthorax pusillus Av + + + + ++ +

410 Limnologica 29 (1999) 4 Table 1. (Continued).

Species Bio H/A H/B T G/A G/B K

Ophrydium hyalinum As +++ +++ ++ + + +++ variabilis Av + + o + + + Oxytricha sp. Av + + + + + ++ q- bursaria Av + + + + ++ + Paramecium putrinum Av + + + + O Platyophrya sphagni Av o ++ O Pseudovorticella quadrata As ++ + + ++ + + Sathrophilus muscorum Av + + + o ++ + algivorous scuticociliates Av + + + + + + bacterivorous scuticociliates Av ++ ++ ++ +++ ++ ++ Spathidium sp. Av + o o + + + Sphaerophrya magna As o + + + amethystinus As/P + o + ++ ++ Stentor igneus As/P + Strobilidium sp. P + + + + + + pustulata Av ++ + + + + + sp. As o O Trachelius ovum Av/P + + + + + + Turaniella vitrea P + + o o Uroleptus caudatus Av + + ++ + +++ O Uroleptus museulus Av + + Urotricha sp. P o + + + Vorticella aquadulcis-complex As + + + ++ + ++ As ++ +++ ++ +++ + ++ -complex As +++ +++ ++ +++ ++ +-I- Vorticella sp. As + + + + +

NAKED Polychaos sp. Av + + + + + Amoeba proteus Av o + + + + Hartmannella sp. Av + + o + + Mayorella cantabrigiensis Av + + + + + Vahlkampfia sp. Av + + + + +

HELIOZOA Acanthocystis turfacea As + + + ++ + ++ Acanthocystis sp. As + + + ++ + + Actinosphaerium nucleofilum As o Chlamydaster sterni As + + + + + Pompholyxophrys punicea As o o + + + sp. As + + + ++ +

Species T/uh T/lh G/uh G/lh K/uh

TESTATE AMOEBA Amphitrema flavum o Arcella discoides + + Assulina muscorum + + + + + Assulina seminulum + Centropyxis minuta + + + Centropyxis aculeata + Euglypha ciliata + + + Heleopera sphagni o Heleopera petricola + + Hyalosphenia elegans + + + ++ + Hyalosphenia papilio ++ ++ ++ Nebela collaris + ++ + + + Nebela militaris ++ + + + Nebela spp. + + + Phryganella acropodia + Trigonopyxis arcula +

Limnologica 29 (1999) 4 411 September 1992 until September 1993. The list shows a slides. This is striking since slide methods generally prefer great variety of protists and comprises only the most impor- sessile species, whereas other artificial substrates favour the tant species on the slides and some easy determinable rare colonization of vagile species (BAMFORTH 1982; WEITZELet species. Only few naked amoebae and heliozoans are listed. al. 1979). The ratio of sessile to vagile and ciliate The testate amoebae were found in 1996 by squeezing water species is 27 : 47 = 0.57 and therefore indicates mesotrophic out of the Sphagnum plants and therefore a different listing is conditions within the bog lakes (ZOLOTAREV1995). applied. They were partly observed on the slides in the The saprobical index of the species listed here is also earlier years. Metazoans were not taken into account, neither mainly oligo- or mesosaprobic. Dinobryon and Salpingoeca, many of the heterotrophic nanoflagellates. Determination for example, avoid saprobic habitats (LEMMERMANN1914); was often only possible to the level. also SLADECEK (1973) defined Salpingoeca as indicator A general evaluation of the colonization of the exposed species for oligosaprobic conditions. ZOLOTAREV (1995) slides shows some differences concerning the species com- showed that in oligosaprobic waters Salpingoecidae domi- position in the four investigated bog lakes. There are many nate, whereas in mesosaprobic waters the colonial species that occurred in all four lakes. Every lake, however, choanoflagellates and in polysaprobic environments vagile also possesses some characteristic species. Especially in the bodonids and heterotrophic are more important. upper region of the Sphagnum mat in Lake Grol3er Barschsee Bodonid and heterotrophic species had only minor a totally different species composition of the periphyton was impact concerning species number and abundance in the pe- observed. The flagellates Chlamydomonas sphagnophila riphyton of the bog lakes (compare STRUDER-KYPKE 1999, Chloromonas angustissima, Euglena acus, Heterochro- this volume). GROL~gRE (1977b, 1978) mostly found alpha- monas sp., ovalis, K. oblonga, and the ciliates to beta-mesosaprobic ciliate species in the Sphagnum mats Cyrtolophosis sp., C. mucicola, Microdiaphanosoma arcua- of acid bog lakes. None of the species observed by him had turn, Microthorax pusillus, Oxytricha sp., Paramecium bur- an oligosaprobic index, but many of them were not classi- saria, Platyophrya sphagni, Sathrophilus muscorum, and fied. Dystrophic lakes contain much organic material, but Uroleptus caudatus occurred rarely or never on the other predominantly in a form that cannot be used by the organ- sampling sites. Some of these observed species are consid- isms. The mineralization of the plant parts is stopped in an ered as characteristic soil protists (e.g. Chloromonas an- early stage, therefore the density of in the bogs gustissima, Microdiaphanosoma arcuatum). This refers to which serve as for is too low for high abun- the intermediate position of the Sphagnum mat, in which the dances e.g. of large filter feeders (GROLIERE 1977b). inner regions are generally submerged, but the outer regions Bacterivorous organisms of the lakes are mostly hetero- may fall dry during water shortage. The milieu in the upper trophic flagellates like Salpingoeca spp., Cyathobodo sp., Sphagnum region is very different from the other habitats of Bodo spp., and Goniomonas truncata (compare STRUDER- the bogs: Due to the permanent new formation of Sphagnum KYPKE 1999, this volume). shoots and the lacking degradation of old plant parts, the A great part of the observed ciliates shows a wide food conditions are rather oligotrophic in this upper horizon. Fur- spectrum which comprises bacteria, blue-green , di- thermore, the pH within the Sphagnum mat is more acidic atoms, green algae, small flagellates, and even small ciliates than in the water body because the Sphagnum plants function (e.g. Uroleptus caudatus, Litonotus lamella, Holophrya sp., as a cation exchanger. Adaptations to the low concentration or Prorodon sp.) in order to cope with the low availability of of nutrients are vagility, a broad food spectrum, or the sym- nutrients. Osmotrophy probably is important in the lakes in biosis with zoochlorellae. The latter is realized by many pro- spite of the little dissolved organic contents. SrtERR (1988) tists that live in the upper region of the Sphagnum mat (e.g. noted that heterotrophic flagellates are able to ingest and use Paramecium bursaria, Platyophrya sphagni, Uroleptus cau- high molecular compounds. In the bog lakes with a high per- datus, Mayorella viridis, Acanthocystis tutfacea, Hyalosphe- centage of little decayed material, this seems to be a imagin- nia papilio, Heleopera sphagni) and was proofed in earlier able strategy for and food metabolism. In contrary to studies (HARNISCH 1925; WENZEL 1953). The lower horizon oligotrophic lakes, dystrophic lakes show a different energy (brown, with dead Sphagmun stems) is dark and has a higher flux: The heterotrophic plankton often has a higher biomass nutrient concentration. production than the phytoplankton, since it is able to use de- Only few sessile species colonized the slides. The most tritus particles or dissolved organic matter (DOM) as energy abundant sessile ciliates were Vorticella campanula, Ophry- source (HESSEN et al. 1990). Mixotrophy is not very common dium hyalinum and specimens of the Vorticella convallaria- in the bog lakes. Also in other oligotrophic waters, complex. Sessile flagellates were represented by Cyathobo- mixotrophic protists are not as abundant as might be as- do sp., Salpingoeca spp., Spongomonas sacculus, Rhipido- sumed considering the benefit of this growth mode (ARNDT dendlvn huxleyi, Protelvspongia lackeyi and few numbers of & BERNIN6ER 1995). Chrysomonads and Bicosoeca lacustris, Cladomonas fruticulosa and Pseudo- composed only a small percentage of the periphyton com- dendlvmonas vlkii. Most species were vagile and a large munity, are almost obligate autotrophic number of planktonic protists was also observed on the (SANDERS & PORTER 1990).

412 Limnologica 29 (1999) 4 Indicator species of bog lakes the following ciliates and flagellates together with other ubiquitous protists and, of course, testate amoebae marks a Most of the species that occurred regularly in the lakes are typical bog lake periphyton community. ubiquitous and common in limnetic habitats (e.g. Bodo, Among the flagellates, Spongomonas sacculus, Rhipido- Chilodonella, Cryptomonas, Gymnodinium, Vorticella). dendron huxleyi, Cyathobodo, and Pseudodendlvmonas Therefore they cannot be regarded as indicator species of species can be assumed as characteristic bog protists. They bog lakes. Compared to eutrophic habitats they reach higher were reported to appear almost exclusively in bog lakes. Al- abundances, since the competition with typical though Spongomonas sacculus and Rhipidodend~vn huxleyi, (e g. scuticociliates that can reach high population densities) e.g., are relatively common, their main distribution was is less important in oligotrophic or dystrophic environments. noted in Sphagnum bogs (HIm3ERD 1976a, 1983). KENT'S Furthermore, many of the ubiquitous species are characteris- (1880) original description of both species is based on sam- tic pioneers of newly exposed substrates and are repressed in ples from bog lakes. They form their matrix from iron and the course of succession (CAIRNS& HENEBRY 1982). manganese compounds. Both elements are sufficiently avail- As for other animal taxa (e.g. insects and vertebrates), a able in the bog lakes (STR~DER-KYPKE& HAUSMANN1998), characterization of the protist fauna in bogs is hard to define maybe this is the reason for the common occurrence of these by certain species. Many of the flagellates and ciliates show species in bogs. Also the Cyathobodo and Pseudoden- high tolerances concerning oxygen, pH range, availability of dlvmonas species were mostly described from Sphagnum food, and DOM in the water, therefore they are not strictly bogs (HIBBERD 1976b, 1985; MIGNOT 1974). bound to certain habitats. Often an exact species determina- Leptopharynx costatus, Platyophrya sphagni, and Ulv- tion is not possible, since adaptations to extreme environ- leptus caudatus are ciliate species which were mostly found ments occur. One example is the rather common symbiosis in bogs or small waters (FoISSNER 1980; GROLI~RE 1975b, with zoochlorellae in Sphagnum mats (or the re- 1977a, 1978; KAHL 1931, 1932; MERMOD 1914; PENARD tention, respectively), and WENZEL (1953) reported from 1922; WENZEL 1953). GROI,IERE (1977b, 1978) defined sev- mosses often stunted forms that were smaller than specimens eral characteristic ciliate species for acid bogs in France, but examined from other waters. An additional problem is the only Leptopharynx costatus, Uroleptus caudatus, Urotricha great variety of habitats in bogs that ranges from dry soil en- ovata and Platyophrya sphagni (described as P. viridis and vironments to planktonic distribution in the residue lakes. synonymized by FOISSNER 1993) were observed during our The species composition of dry mosses, wet Sphagnum mats study. Cyclidium sphagnetorum was regarded by GROLIERE and the free water-body differs considerably from each other. (1978) to be a characteristic species of the bogs with relative This makes a comparison to other reports difficult, since dif- abundances of up to 95-99%. This species was not observed ferent methods of sampling lead to very different results. in our investigated bogs. Neither did MERMOD (1914) and WENZEL (1953) compared the ciliate community and species WENZEL (1953) find C. sphagnetorum during their studies. of different bogs. Since he mainly investigated the mosses of GROHERE (1975, 1977a, 1977b, 1978), however, investigat- dry habitats, he found many soil ciliates (e.g. ). In ed very acid habitats with a pH ranging from 3-5, this may spite of the observation of some soil ciliates, the greatest per- be one reason for the lacking of his characteristic species in centage of the species we noted were aquatic, and therefore our subneutral environments. He noted that the most abun- only few species described by WENZEI~ (1953) are in accor- dant ciliates of this upper region in the bogs harboured dance to our reports. Cinetochilum margaritaceum, Cyrtolo- zoochloreUae in their cytoplasm. This was confirmed by the phosis mucicola, Leptopharynx costatus, Litonotus lamella, study of STR~DER-KYeKE(1999, this volume), but also many Microdiaphanosoma arcuatum, Sathrophilus muscorum, and colourless ciliates and heterotrophic flagellates occurred in Uroleptus caudatus were species of his samples that oc- this upper region. curred in the investigated bog lakes. Also the sphagnophil species described by GROLIgRE Testate amoebae (1978), were not observed in the periphyton (except Lep- topharynx costatus). This may be due to the applied methods The upper, moist horizons of the Sphagnum mats in Lake (squeezing of the Sphagnum versus exposure of slides), to Teufels-See were dominated by Hyalosphenia papilio, a different investigated habitats or it may represent the fact characteristic species of oligotrophic bog lakes that harbours that no characteristic protist species of bogs exist, but that zoochlorellae. Other typical zoochlorellae-bearing species these most abundant species are generally common. Another like Heleopera sphagni, Placocista spinosa, and especially reason may be a beginning eutrophication of the investigated Amphitrema spp. were much less abundant or did not appear bog lakes which is also indicated by our investigation of the at all. Colourless species like Hyalosphenia elegans, Nebela testate amoeba community in the Sphagnum of the lakes (see ssp., and Assulina muscorum, however, that also occur in below). habitats of higher trophy, e.g. in swamps and in the lower Nevertheless, some species seem to be more common in horizons of the Sphagnum mats, were observed in this upper dystrophic bogs than in other habitats. A joint occurrence of region. The lower and dry region of the Sphagnum revealed a

Limnologica 29 (1999) 4 413 typical community of testate amoebae with dominance of heterotrophic flagellates, but also nematodes, bdelloid ro- two Nebela species. Besides that, many other colourless but tifers, and mites. The water of the squeezed Sphagnum no zoochlorellae-harbouring species occurred. The density showed a distinct sediment of detritus which had an C:N- of testate amoebae was comparable to other bog lakes for ratio of 18 and therefore must be regarded as an easy degrad- both horizons in Lake Teufels-See. able and favourized source of nutrients. The pH of the In Lake Grof3er Barschsee similar results were obtained: squeezed water revealed subneutral conditions that ranged The upper horizon was dominated by Hyalosphenia papilio, around 6.3, and once it even reached 6.8. but apart from this and rare observations of Amphitrema The lack of typical testacean indicators and the occur- flavum, no other characteristic species with zoochlorellae rence of species of the lower horizon in the upper region may were noted. Instead of this, colourless species like Centropy- be due to the eutrophication of the bogs which definitely xis minuta, Nebela spp., and Hyalosphenia elegans occurred. could be proofed by the comparison of the distribution of tes- The latter dominated the lower humid horizon, where a strik- tate amoebae in the years 1963 and 1992-1998. The commu- ing low density of testate amoebae was recognizable. Mostly nity structures of testate amoebae that were as described in species of the genera Arcella, Nebela, and Centropyxis were 1963 (SCHONBORN 1963) could be confirmed until 1972. found. After that, no studies were made until 1992. Investigations of The upper, moist horizon of Lake Kleiner Barschsee re- the years 1992, 1994 and 1996-1998 showed that the com- vealed a very high density of testate amoebae. Dominant was munity structure had changed distinctly. Amphitrema species Hyalosphenia papilio, all other species were colourless, e.g. like A.flavum and A. stenostoma which are very sensitive in- Nebela spp., Centropyxis minuta, Hyalosphenia elegans, and dicator species for oligotrophic bogs and are restricted to the Euglypha ciliata. upper horizon of the Sphagnum, were rarely found. Besides As on the slides of the upper region, the squeezed @hag- that, Placocista spinosa could not be observed. Most species num samples showed relative high abundances of other pro- of the lower region are also distributed in swamps (e.g. tists with zoochlorellae (naked amoebae, heliozoans and cili- Hyalosphenia elegans, Nebela spp., Centropyxis spp., ates), photoautotrophic flagellates of the genus Euglena and Trigonopyxis spp., and Assulina spp.) (ScHONBORN 1962b,

Testate amoebae in moist Sphagnum mats

1963 and before it Recorded since 1992

Decreasing density row: Decreasing density row:

Upper horizon: Hyalosphenia papilio* Hyalosphenia papilio* green, living Sphagnum k Amphitrema flavum* Hyalosphenia elegans stems Heleopera sphagni* Nebela tincta Amphitrema stenostoma * Euglypha ciliata Centropyxis minuta Assulina muscorum Ptacocista spinosa* Centropyxis minuta Nebela collaris

Lower horizon: Nebela tincta Hyalosphenia elegans brown, dead Sphagnum Assulina muscorum Nebela tincta stems Hyalosphenia etegans Euglypha ciliata Nebela collaris Nebela collaris Nebela minor Nebela militaris Nebela militaris Centropyxis minuta Centropyxis minuta

Fig. 2. Stratification of testate amoebae in the moist zone of Sphagnum mats. Summarized results from Lake Teufels-See, Lake Groger Barschsee and Lake Kleiner Barschsee. Explanation: Species marked with an asterisks = with zoochlorellae.

414 Limnologica 29 (1999) 4 1963). Apart from the changes in species composition, the FLAGELLATES stratification of the Sphagnum mats is mixed up: Colourless species of the lower horizons also occur in the upper region • Bodo designis SKUJA, 1948 and Bodo saltans EHRENBERG, of the mat, showing that this horizon has become more nutri- 1831 Phylum ; Subphylum Kinetoplasta; Class Bodonea; ent rich, due to an eutrophication of the bogs. In earlier stud- Order ies, only zoochlorellae-harbouring species were found in this upper zone (Fig. 2). B. designis was firstly described from acid lakes by SKUJA (1948) and can be regarded as ubiquitous. The average size Characteristic flagellate and ciliate species is 10 x 3 ~m with a long-ovoid shape. Anterior there is a of the lakes and their seasonal distribution small rostrum developed and the cytostom is located at the tip of this prolongation. The flagellate glides steadily over The flagellates were classified according to HAUSMANN~; the substrate. In contrary to B. designis, B. saltans is only Ht2LSMANN (1996), the ciliates according to GRASSt~ (1994). 6-7 x 3~m in size and more compact in shape. The move- Figs. 3-8 summarize the seasonal distribution of important ment is a characteristic jumping and gliding on the substrate. flagellate and ciliate species. Both species are very common in fresh-waters and feed on

30 ~ 5:,t Bodo designis Bodo saltans 40"

20 Goniomonas truncata 15o~

Salpingoeca spp. 20' Cyathobodo sp.

30~ Spongomonas sacculus 8" Rhipidodendron huxleyi Uroleptus caudatus Cyrtolophosis sp. 11 Cyrtolophosis mucicola

:-:,x,:,::: Chilodonella uncinata Leptopharynx costatus

20 Ophrydium hyalinum 40 "

Vorticella campanula 3T

30 Vortic¢lla convallaria- complex Sep. Oct. Nov. Dec. J/F Mar. Apr. May Jun. Jul. Aug. Sep.

Fig. 3. Abundances (cm-2) and seasonal distribution of the characteristic ciliate and flagellate species in Lake Himmelreichsee, site A. The abundances of Spongomonas sacculus and Rhipidodendron huxleyi are noted as colonies/cm 2.

Limnologica 29 (1999) 4 415 bacteria. They were found during the year at all sampling Minor differences concern the somewhat higher abundance sites and were able to prevail when the competition with of B. saltans in Lake Himmelreichsee and the greater domi- other species was low. Mainly from December 1992 to July nance of B. designis in Lake GroBer Barschsee, site B in 1993 they reached higher numbers. In the course of the sum- April and May 1993. mer, B. designis and B. saltans were repressed from the Bodonid flagellates are bacterivorous and feed on sub- slides which were densely colonized by green algae. Further- strates like detrital flakes and submersed plant parts more, the competitive pressure of other protists (mainly cili- (SANDERS et al. 1989). Most of the species are ubiquitous and ates) was very high at that time. During the winter the characteristic pioneer species of newly exposed substrates amount of bacteria was so low that bodonids occurred only (CAIRNS & HENEBRY 1982). RAILKIN(1995) recently investi- in small numbers on the slides. In general, the seasonal dis- gated the periphyton community of marine habitats and tributions of both species were comparable to each other. showed that bodonids even compose up to 40% of the her-

307

Bodo designis

2O 40I Bodo saltans 3-"6"" 15 , Goniomonas truncata 400"

30£

20(

Salpingoeca spp. Cyathobodo sp. 45 "i 30" 15 Spongomonas sacculus Rhipidodendron huxleyi Uroleptus caudatus t Cyrtolophosis sp. •~ Cyrtolophosis mucicola 15 Chilodonella uncinata Leptopharynx costatus 250"-? 200'

150100 i 50 ~ Ophrydium hyalinum 105"75 __ 45 15 7ff Vorticella campanula ~ Vorticella convallaria- complex Sep. Oct. Nov. Dec. J/F Mar. Apr. May Jun. Jul. Aug. Sep.

Fig. 4. Abundances (cm-:) and seasonal distribution of the characteristic ciliate and flagellate species in Lake Himmelreichsee, site B. The abundances of Spongomonas sacculus and Rhipidodendron huxleyi are noted as colonies/cm 2.

416 Limnologica 29 (1999) 4 erotrophic flagellates in these communities. Bodonids reach species were present in high numbers, suggesting a plank- highest abundances in polysaprobic waters; in oligo- and tonic distribution in surface near regions. mesosaprobic habitats their species and individual number is considerably lower (ZOLOTAREV1995). • Salpingoeca clarkii STEIN, 1878 and Salpingoeca buet- schIii LEMMERMANN, 1914 • Goniomonas truncata (FRESENIUS, 1858) STEIN, 1878 Phylum Choanoflagellata; Order Choanoflagellida Phylum Chromista; Subphylum Cryptomonada; Order Cryptomona- Salpingoeca clarkii lives in a which is attached to dida the substrate with a stalk. The length of the lorica is 15-20 This primary colourless is ubiquitous pre- pro. The choanoflagellate also builds a lorica of the same sent in fresh-waters. The flagellate is 10-15 pm long and re- length which, however, is unstalked. Choanoflagellates are veals a rigid ovoid shape. Obvious are the ejectisomes and typical filter feeders that mainly inhabit mesotrophic waters. the two flagella at the truncated anterior pole. G. trunca- While the cells of S. buetschlii colonized the substrates in ta is mainly found in the periphyton and is osmo- and groups of 5 to more than 100 individuals, S. clarkii was phagotrophic. It was observed throughout the year in low mostly found singularly or in groups of only few cells. Since abundances on the periphyton, only in Lake Himmelreichsee both species of Salpingoeca always occurred simultaneously extreme peaks were reached in December 1992 and March on the slides, they were not distinguished. All sampling sites 1993. The low individual number per cm 2 indicates a perma- revealed the same seasonal distribution of Salpingoeca. nent occurrence of G. truncata that was not always noted. At They were represented from May to September 1993 on the site B of Lake Grof3er Barschsee autotrophic cryptomonad slides, and comprised during the early summer months a

4" Bodo designis Bodo saltans , Goniomonas truncata 150"

I(R

Salpingoeca spp. Cyathobodo sp. 120"! 8(- 4~ Spongomonas sacculus I Rhipidodendron huxleyi Uroleptus caudatu 'r ,~ Platyophrya sphagni 30" 15 Chilodonella uncinata Leptopharynx costatus Ophrydium hyalinum

Vorticella campanula

Vorticella convallaria- complex Sep. Oct. Nov. Dec. J/F Mar. Apr. May Jun. Jul. Aug. Sep.

Fig. 5. Abundances (cm "-) and seasonal distribution of the characteristic ciliate and flagellate species in Lake Teufels-See. The abundances of Spongomonas sacculus and Rhipidodendron huxleyi are noted as colonies/cm 2.

Limnologica 29 (1999) 4 417 dominating part of the periphyton. They preferably colonize salpingoecids appeared generally only in low abundances. At filamentous green algae, zygnemales of the genus Spirogyra site B of Lake Groger Barschsee the bacterial density was or diatoms (preferably of the genus Tabellaria) that were not high enough for filter feeders and additionally almost no most abundant at this time. In the further course of the sum- filamentous green algae grew on the slides. mer, their number decreased and in the winter months rarely species of this genus were observed. Also in the plankton of other lakes salpingoecids are found more frequently during • Cyathobodo sp. Heterotrophic flagellates incertae sedis; Order Pseudodendromona- late spring and summer (SANDERS et al. 1989). Their de- dida crease in the course of the summer may be due to the stronger occurrence of peritich ciliates and the competition This genus comprises very small (5 ~m) and characteristi- with these larger protists. A comparison of the seasonal dis- cally triangular shaped flagellates. The cell is attached to the tribution of Vorticella and Salpingoeca reveals an alternation substrate or the air-water-interface by a stalk. All described of the species of the V. convallaria complex and the flagel- species of the genus Cyathobodo were found in Sphagnum lates. In Lake Kleiner Barschsee, where OphlTdium hyal- bogs, therefore they can be considered as typical indicator inure was a significant component of the periphyton, the species for this habitat. Cyathobodo sp. was a characteristic

30"1

Bodo designis 30"

Bodo saltans .~ Goniomonas truncata

Salpingoeca spp. 20" Cyathobodo sp.

150 t 100 50 Spongomonas sacculus 75

Rhipidodendron huxleyi Uroleptus caudatus Cyrtolophosis sp. Chilodonella uncinata Leptopharynx costatus Ophrydium hyalinum

25 Vorticella campanula

150 100" 50 Vorticella convaUaria- complex Sep. Oct. Nov. Dec. J/F Mar. Apr. May Jun. Jul. Aug. Sep.

Fig. 6. Abundances (cm ~) and seasonal distribution of the characteristic ciliate and flagellate species in Lake Groger Barschsee, site A. The abundances of Spongomonas saccuhts and Rhipidodendron huxleyi are noted as colonies/cm 2.

418 Limnologica 29 (1999) 4 representative during the winter months and in spring, when • Spongomonas sacculus KENT, 1880 and Rhipidodendmn only few green algae colonized the slides. With the exception huxleyi KENT, 1880 of Lake Kleiner Barschsee, Cyathobodo sp. was found in all Heterotrophic flagellates incertae sedis; Order Spongomonadida lakes but with higher numbers in the larger lakes. Heterotrophic flagellates are pioneer species and com- The cells of these colonial flagellate species are embed- prise during the winter the main part of the periphyton com- ded in a granular matrix which is irregularly shaped for munity (ZOLOTAREV 1995). Since Cyathobodo is a sessile Spongomonas sacculus and tree-like for Rhipidodendron , in spring and summer the larger or colonial pro- huxleyi. Single cells are ovoid or cylindrical in shape and tists repress this species. On the slides, the species frequently 6-10 ,um long. The apical pole reveals a cytoplasmic prolon- was found among larger Vorticella assemblies. Maybe it gation that partly surrounds the two flagella. Spongomonas profits from the water current produced by the ciliates, and sacculus and R. huxleyi are characteristic protist species of ingests the bacteria in it. acid Sphagnum bogs and can be considered as indicator

..^.

des~n~

to saltans niomonas truncata tlpingoeca spp. 7yathobodo sp. ~pongomonas sacculus Rhipidodendron huxleyi Uroleptus caudatus

9phosis sp.

,lophosis mucicola

(yophrya sphagni

iilodonella uncinata

.eptopharynx costatus Ophrydium hyalinum Vorticella campanula Vortic¢lla convaUaria- complex Sep. Oct. Nov. Dec. J/F Mar. Apr. May Jun. Jul. Aug. Sep.

Fig. 7. Abundances (cm-2) and seasonal distribution of the characteristic ciliate and flagellate species in Lake GroBer Barschsee, site B. The abundances of Spongomonas sacculus and Rhipidodendron hualeyi are noted as colonies/cm 2.

Limnologica 29 (1999) 4 419 gnis !ans ,nas truncata

~eca spp. monas sacculus 9phosis sp.

donella uncinata opharynx costatus

9phrydium hyalinum Vorticella campanula Vorticella convallaria- complex Sep. Oct. Nov. Dec. J/F Mar. Apr. May Jun. Jul. Aug. Sep.

Fig. 8. Abundances (cm 4) and seasonal distribution of the characteristic ciliate and flagellate species in Lake Kleiner Barschsee. The abun- dances of Spongomonas sacculus and Rhipidodendron huxleyi are noted as colonies/cm2.

species. They were found at all sampling sites, but the abun- CILIATES dances (noted as colonies/cm2) varied considerably. During the winter S. sacculus and R. huxleyi occurred • Uroleptus caudatus STOKES,1886 only in low individual numbers on the slides. Besides that, Class Hypotrichea; Order Oxytrichida; Suborder Stichotrichina the colonies were very small (4-8 individuals) since the ini- This hypotrich ciliate is a characteristic species of the tial colonization is much slower during the winter. Both Sphagnum mat. The cell is 150-200 pm long and easy to de- species had a similar seasonal distribution, but R. huxleyi termine because of its slender shape with the distinct head never reached abundances as high as S. sacculus. These re- and tail. U. caudatus inhabits the upper centimeters of the sults are in accordance with studies from KENT (1880) who Sphagnum mats and it feeds on diatoms, green and blue- found both species associated in bogs with higher abun- green algae as well as on bacteria. In a depth of 10-15 cm be- dances for Spongomonas than for Rhipidodendron. neath the water surface this species rarely occurs. With the Since the flagellates are no filter feeders but phago- exception of Lake Kleiner Barschsee, U. caudatus was pre- and/or osmotrophic (STR~DER-KYPKE& HAUSMANN 1998), sent at all sampling sites. The highest abundances were noted their occurrence mainly in late summer may be due to the ac- at site B of Lake Grol3er Barschsee, where values of cumulation of nutrients in the water during the summer. In 25 individuals/cm2 were reached from April to September spring and summer new Sphagnum mats develop and also 1993. other plants grow on these mats. Because of their degrada- GROLIE~E (1975b) found U. caudatus in various kinds of tion, there is an enrichment of nutrients in the lower regions habitats of acid bogs in France, but it reached highest abun- of the Sphagnum mats and sufficient food for the flagellates dances in the submerged upper region of the Sphagnum mats is provided. This is supported by the fact that these colonial (GROLIERE 1977b). In general, U. caudatus is an ubiquitous flagellates reached higher abundances in the lower regions of species, that never occurs in high individual numbers. This the Sphagnum mats. A second limiting factor may be a lower was confirmed by the occasional and low abundance at the concentration of iron and manganese during the rest of the other inverstigated sites. The seasonal distribution of U. cau- year which the flagellates need for the synthesis of their ma- datus is in accordance with the observations of GROLIERE trix granula. (1977b). He noted an occurrence from April to June and a

420 Limnologica 29 (1999) 4 peak in May 1993. The observed high individual numbers • Platyophtya sphagni (PENARD, 19221) FOISSNER, 1993 from April to September 1993 correlate with the generally Class ; Subclass Colpodia; Order Cyrtolophosidida high abundances of ciliates in the periphyton. At this time, The third colpodid ciliate is metabolic, 50-70 pm long sufficient coccoid green algae colonized the slides and pre- and harbours numerous zoochlorellae in the cytoplasm. P. sented the main food source of U. caudatus. sphagni was repeatedly found in Sphagnum bogs and there- Striking was the presence of two morphotypes: a colour- fore it can be considered as indicator species for this habitat. less, slender form and a green, more rounded form with The species occurred in September 1992 and from May to zoochlorellae. Also FO~SSNER (1980) did not exclude the oc- September 1993 on the slides of site B in Lake Groger currence of zoochlorellae-harbouring specimens within this Barschsee. The abundances ranged from 10-50 individu- ciliate species. This chloroplast retention or facultative sym- als/cm 2. During the winter it was not present on the slides. biosis with zoochlorellae represents an adaptation to rather Platyophrya sphagni was described from Sphagnum bogs oligotrophic biotops (HARNISCH 1929). and small ponds (FoISSNER 1993; GROLII~RE 1977a). Its re- striction to the upper regions of the Sphagnum mat is in ac- • Cyrtolophosis sp. and Cyrtolophosis mucicola STOKES, cordance to observations of HARNISCH(1929) and GROL~ERE 1885 (1977b). Class Colpodea; Subclass Colpodia; Order Cyrtolophosidida

These small, only 20-28 pm long ciliate species are • Chilodonella uncinata EHRENBERG, 1838 vagile and glide over the substrate. C. mucicola builds small Class ; Subclass Cyrtophoria; Order Chilodonellida hyaline loricas, which could not be definitely identified for This species is ubiquitous and colonizes many different Cyrtolophosis sp., although there are some evidences that habitats. C. uncinata is 30-50 pm long and several kineties they may exist for both species. The infraciliature is com- of varying length are running over the ventral side. Dorsally, prised of few, slightly spirally running kineties. Anterior is there are no kineties but 2 dorsal brushes. The cytopharynx is the buccal region with 3-5 adoral membranelles located. The supported by a basket of . C. uncinata was one distinguishing character of the two species are few (10-15) of the few species that occurred throughout the year in the spherical symbiontic green algae in the cytoplasm of Cyr- periphyton and was observed at all sampling sites. The abun- tolophosis sp. which may be zoochlorellae. Zoochlorellae- dances were relative low, peaks were reached in the fall of harbouring species of Cyrtolophosis haven't been described 1992 and in the spring of 1993. yet. The investigated species, however, showed a high con- As a typical pioneer species on newly exposed substrates, stancy in number and position throughout the cytoplasm of Chilodonella uncinata grazes on bacteria of the surface of the internal green algae. Apart from that, no digestion stages the substrates and is most frequently found during the initial of them were found, suggesting a symbiosis with zoochlorel- phase of the colonization. KAHL (1931) described C. uncina- lae. It remains to be solved, if this symbiosis with zoo- ta from bog lakes. chlorellae is only an adaption of C. mucicola to oligotrophic environments (comparable to U. caudatus), or if the erection • Leptopharynx costatus MERMOD, 1914 of a new species is justified. C. mucicola is abundant in most Class ; Subclass Nassulia; Order Microthoracida fresh-waters and can be considered as ubiquitous. FOISSNER et al. (1991) and FOISSNER (1993) noted the saprobity as This species is very small (20-40 pm long) and vagile. oligo- to polysaprobic. Cyrtolophosis sp. and C. mucicola Few kineties are curved on the ventral side of the cell. Ante- are species that inhabited mainly the upper region of the rior to the oral region, oblique running ciliary rows form a Sphagnum mat. They were not represented in the periphyton dense tuft of cilia. Most reports of L. costatus are from ter- of Lake Teufels-See. Both species reached highest abun- restrial biotopes and from mires. Together with other species dances in May 1993 at site B of Lake GroBer Barschsee. it can be considered as an indicator species for acid, dys- During the winter and at the other sampling sites, Cyr- trophic habitats. L. costatus was found throughout the year at tolophosis occurred only occassionally. all sampling sites. The abundances were very low within the The milieu spectrum of C. mucicola is widespread, there- range of 1-8 individuals/cm 2. fore high abundances are not related to certain abiotic fac- GROLI~RE (1977b) observed high abundances of Lep- tors, but to the lack of competitors (FoISSNER et al. 1991; topharynx costatus in various bogs in France, mainly in FOISSNER 1993). This explains the low individual numbers, September and October, as well as partly in May. During our since the slides were colonized by many different protists. investigations, however, L. costatus occurred regularly but in GROLIERE (1977b) noted the highest abundances of C. muci- low abundances (often as single observation) on the slides. cola at water temperatures below 10 °C. This observation Only in the upper regions of the Sphagnum mats, a compara- could not be confirmed by our investigations, since the ble seasonal distribution was observed. FOISSNER et al. species also occurred during the summer months at higher (1994) ranked this species as oligo- to beta-mesosaprobic. temperatures, up to 20 °C. Because of the regular occurrence almost exclusively in

Limnologica 29 (1999) 4 421 Sphagnum bogs, L. costatus can be considered as indicator peak in early spring. In contrary, the species of the V. conva- species of this habitat (GROLIgRE 1978). Its generally low in- llaria complex showed highest abundances in early summer. dividual numbers are in accordance with the results of BAM- Since the nutritional needs are approximately the same for FORTH (1982) who compared different artificial substrates: both species, the change in dominance may be due to abiotic only approximately 50% of all heterotrophic vagile species factors. Eventually the acidification of the water by the were observed on glass-slides. growing Sphagnum plants during the summer is one reason for the decrease in the individual numbers of V. campanula, • Ophrydium hyalinum WRZESNIOWSKI,1877 since this species avoids acid habitats (FoISSNERet al. 1992). Class ; Subclass Peritrichia; Order This sessile, colonial peritrich ciliate resembles the better Trophy of the investigated bog lakes known species O. versatile. In contrary to this species, how- The investigations of the periphyton community and the tes- ever, it harbours no zoochlorellae and its spherical colonies tate amoebae, as well as general observations point to a eu- reach only maximum sizes of a few millimeters in diameter. trophication of the bog lakes during the last 20 years. The extended cell is approximately 200 pm long. At the pos- The Sphagnum mat became 25-50% smaller, Ledum terior ends the cells are linked by dichotomously branched palustre advanced towards the lake, many other herbs grow strands. Originally described by WRZESN~OWSKI(1877) from on the Sphagnum mat that were not abundant before. Al- a small pond, O. hyalinum can be considered as an indicator though Drosera plants are still optimally distributed within species of acid, dystrophic waters. It was found in all lakes, the bogs, the other plants can be considered as a source for but in varying abundances. Maximal individual numbers the formation of detritus and for the raising of the pH (from were reached in September 1992 as well as in May and 5.2-5.7 in 1963 to 6.3-6.8 in 1996). This, however, enables a September 1993. better degradation of Sphagnum and other plant parts and Among the ciliates, the lower regions of the Sphagnum leads to an increasing trophy of the lakes. Also the low C:N- mats were inhabited with a high percentage by sessile ratio of the sediment may be due to the invasion of different species. Vagile and free-swimming species were only found herbs and resulted in a further fertilization of the bogs. Nor- in low abundances. As mentioned before, the use of of glass- mally, Sphagnum residues reveal a C:N-ratio of >30 and are slides as artificial substrates prefers sessile species (BAM- therefore difficult to decay. Subsequently, bacteria, het- FORTH 1982; WEITZEL et al. 1979; WILBERT 1969). Apart erotrophic flagellates and higher organisms colonized the from that, large sessile filter feeders like peritrich ciliates Sphagnum and repressed the original community. The find more food in this region of the Sphagnum mats than in changes in the distribution and occurrence of some species the upper, green horizon. Ophrydium hyalinum reached of testate amoebae as well as the protist species composition highest abundances in Lake Kleiner Barschsee, in which in the periphyton also indicate more mesotrophic conditions only rarely vorticellids were observed. Explanations for the in the investigated bog lakes. Although still a vertical zoning repression of the peritrichs during the summer may be the exists, more and more heterotrophic species and such with- predation pressure by metazoans like rotifers and cladocer- out zoochlorellae are found in the upper region of the Sphag- ans (ARNDT 1993; WmBERT 1969) or the lack of nutrients and num mats. The lower regions are definitely mesotrophic. insufficient bacterial densities during this time. Also the comparison with other studies (e.g. GROLI~RE) shows distinct differences in the characteristic species which • Vorticella campanula EHRENBERG, 1831 and Vorticella may in part be due to the eutrophication of the investigated convallaria-complex bogs. Since the bog lakes are located within large forest Class Oligohymenophorea; Subclass Peritrichia; Order Sessilida areas, they show no direct anthropogenic sources which may V. campanula is 50-150 pm long and the cytoplasm ap- have caused this eutrophication. Therefore, the fertilization pears dark due to lipid droplets. Therefore it is easy to distin- only could have happened through the air (entry approxi- guish from other Vorticella species. The species of the V. mately 20 kg N/ha. a) or climatic changes. In the past in- convallaria complex, however, are hard to determine by creasing dryness frequently has been resulted in a rapid eu- means of live observations. They are bell-shaped, 40-95 pm trophication of Sphagnum bogs, because herbs and trees long and 35-45 pm broad. The length of the stalk is very could colonize the mats. variable. The of J-shaped and the rim of the peristom distinctly surpasses the body. Both Vorticella species - as other peritrichs - are ubiquitous and very com- Acknowledgements: The study was carried out at the Institute of Zoology, Free University of Berlin, Germany. It was supported by mon in many fresh-waters. The species were found in all grants from the State of Berlin ("Nachwuchsf6rdertmgsgesetz" and lakes with varying abundances. "Sonderprogramm zur F/Srderung von Nachwuchswissenschaft- Vorticella campanula does not only feed on bacteria, but lerinnen") to M. C. STRUDER-KYPKE.We wish to thank Prof. Dr. K. also on algae and detritus. The species is very common and HAUSMANNwho sustained this study on a large scale and in whose indicates mesosaprobic habitats. The annual cycle reached a laboratory most of the work was done. Permissions to take samples

422 Limnologica 29 (1999) 4 from the protected lakes were given by the "Ministerium ftir GROLII~RE, C.-A. (1975a): 12tude de quelques cilids hymdnostomes Umwelt, Naturschutz und Raumordnung des Landes Brandenburg - des eaux acides de la region de Besse-en-Chandesse. Ann. Stat. Abt. Naturschutz -" and the "Amt ftir Forstwirtschaft Fttrstenberg". Biol. Besse-en-Chandesse 9: 79-109.

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- - BENNETT, S. J. & DEBIASE,A. E. (1989): Seasonal patterns of W~ZESN~OWSK~, A. (1877): BeitrSge zur Naturgeschichte der Infu- bacterivory by flagellates, ciliates, rotifers, and cladocerans in a sorien. Z. wiss. Zool. 29: 267-323. freshwater planktonic community. Limnol. Oceanogr. 34 (4): ZOLOTAREV, V. (1995): Microperiphyton flagellate communities, 673-687. their characteristics and functional groups. Cytology 37 (11): SCHLENKER, G. (1908): Das Schwenninger Zwischenmoor und zwei 958-963. Schwarzwald-Hochmoore im Bezug auf ihre Entstehung. Pflan- zen und Tierwelt. Geol.-biol. Untersuch. von Torfmooren 3: 1-279. SCHONBORN, W. (1962a): Neue Testaceen aus dem Grogen Stechlin- see und dessen Umgebung. Limnologica 1 (1): 83-91. Received: September 2, 1998 - (1962b): Zur Okologie der sphagnikolen, bryokolen und terri- kolen Testaceen. Limnologica 1 (3): 231-254. - (1963): Die Stratigraphie lebender Testaceen im Sphagnetum der Hochrnoore. Limnologica 1 (4): 315-321. Authors' addresses: Dr. MICHAELASTRISDER-KYPKE, College of - (1990): Analyse subfossiler Protozoenschalen der Sedimente Biological Science, Department of Zoology, University of Guelph, eines kleinen sauren Waldsees (Kleiner Barsch-See, n6rdliche Guelph, Ontario N1G 2W1, Canada. DDR). Limnologica 21 (1): 137-145. e-mail: [email protected]

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