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Diurnal and seasonal variations in grazing by bacterivorous mixotrophs in an oligotrophic clearwater lake

Författare:
  • Carina Pålsson
  • Wilhelm Granéli
Publiceringsår: 2003
Språk: Engelska
Sidor: 289-307
Publikation/Tidskrift/Serie: Archiv für Hydrobiologie
Volym: 157
Nummer: 3
Dokumenttyp: Artikel i tidskrift
Förlag: E. Schweizerbart Science Publishers

Abstract english

The biomass and bacterial ingestion rates of mixotrophic phytoflagellates were examined on diurnal and seasonal scales in oligotrophic Lake Skarlen (S. Sweden). Ingestion rates were measured using fluorescent microspheres in situ on three depths every 6(th) hour during 24 hours in summer in order to quantify diurnal variations and once at midday during autumn, winter and spring. Mixotrophic phytoflagellates composed a large part of the phytoplankton biomass (18-31 %) throughout the year. Nonetheless, calculations suggest that the mixotrophs only consumed between 0.5 and 4.4 % of the bacterial carbon production, with the highest consumption percentage in winter under ice. Two groups of algae, Cryptomonas spp. and Dinobryon spp., were commonly found with ingested prey and both exhibited significant diurnal differences in bacterial ingestion rates with the highest mean rates measured in late afternoon (0.50 and 0.27 bacteria cell(-1) hour(-1), respectively) and very low rates during night (0.09 and 0.06 bacteria cell(-1) hour). In Cryptomonas spp., ingestion rates also varied.somewhat over the year and bacterial ingestion was highest during winter (0.57 bacteria cell(-1) hour), possibly as a result of the lengthy impaired light climate.

Keywords

  • Ecology

Other

Published
  • ISSN: 0003-9136
Wilhelm Granéli
E-post: wilhelm [dot] graneli [at] biol [dot] lu [dot] se

Professor emeritus

Akvatisk ekologi

+46 70 279 82 34

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Akvatisk ekologi