caa a22 4500 469077581 CHVBK 20180323132939.0 cr unu---uuuuu 170328e19920101xx s 000 0 eng 10.1007/BF00197028 doi (NATIONALLICENCE)springer-10.1007/BF00197028 Korhola A. Department of Geography, University of Helsinki, Hallituskatu 11, SF-00100, Helsinki, Finland aut The early holocene hydrosere in a small acid hill-top basin studied using crustacean sedimentary remains [Elektronische Daten] [A. Korhola] The hydroseral development of a former small lake in Southern Finland was studied by means of subfossil cladoceran remains, diatoms, pollen, plant macrofossils and other sediment data. The diatom analysis shows the lake to have become markedly acid during the Early Holocene. This is reflected in the cladoceran communities in the form of a fall in the proportions of Bosmina longirostris etc. and a reciprocal rise in Bosmina (Eubosmina) longispina, an increase in the proportions of the chydorid species indicative of acidity, and the appearance of certain new morphotypes. The concentrations of both planktonic and littoral species and the numbers of such species increase with acidification. Advancement in the hydroseral succession is reflected in the disappearance of benthic species from the chydorid communities and a pronounced increase in exclusively phytophile species. Sedimentation and the drop in water levels are seen to have led to a spread of helophytes and floating-leaved plants over the water body around 6500-7000 B.P., and a vegetation-filled swamp was created at the site. The zooplankton was practically exterminated, but the concentrations of littoral cladocerans reached their peak at this point. The basin became overgrown completely at the beginning of the Subboreal chronozone (approx. 4600-4800 B.P.), simultaneously with the low-water phase observed in many lakes. It became covered with a Sphagnum stand, and this in turn led to complete destruction of the cladoceran communities. The planktonic/littoral ratio among the Cladocera closely reflected the relation between open water and the macrophyte zone as a function of time. Climatically induced rises and falls in water level are shown to have played a significant role in promoting the advancement of the hydroseral succession. Kluwer Academic Publishers, 1992 hydrosere nationallicence natural acidification nationallicence zooplankton nationallicence diatoms nationallicence water level fluctuations nationallicence Journal of Paleolimnology Kluwer Academic Publishers 7/1(1992-01-01), 1-22 0921-2728 7:1<1 1992 7 10933 https://doi.org/10.1007/BF00197028 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00197028 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Korhola A. Department of Geography, University of Helsinki, Hallituskatu 11, SF-00100, Helsinki, Finland aut NATIONALLICENCE 773 0- Journal of Paleolimnology Kluwer Academic Publishers 7/1(1992-01-01), 1-22 0921-2728 7:1<1 1992 7 10933 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer