In situ photochemical activity of the phytobenthic communities in two Antarctic lakes

Sakae Kudoh, Yukiko Tanabe, Masahiro Matsuzaki, Satoshi Imura

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Abstract

Photochemical activity of phytobenthic communities in two freshwater lakes in East Antarctica was estimated using a submersible pulse-amplitude modulation (PAM) chlorophyll fluorometer, to answer the following questions: (1) Are the communities under bright summer photosynthetically active radiation (PAR) photosynthetically active? (2) If active, which community shows the most active signals? (3) Where is the most productive part (or depth) in the lake? Our limnological measurements indicated the two lakes were ultra-oligotrophic. Diving observations revealed that the phytobenthos of the lakes was moss-dominated which had different life-forms (moss shoots in shallow depths of both lakes, moss-pillars in the shallow lake, pinnacle moss-microbial complex community in the deeper lake). In addition, various mat-forming microbial communities inhabited the lake beds. In situ measurements of photochemical parameters indicated that shoots of mosses living just below the littoral slope, and the apical part of the moss pillars, had the highest photosynthetic activity in open water summer conditions, but mat-forming microbial communities and the other moss-microbial complex communities, showed rather lower activity. Most of the mat-forming phytobenthos surface also showed positive photosynthetic activity, but there were some cases of negligible signals in the shallow depth. This suggests that the photosynthetic activities of mat-forming communities in the shallow water were suppressed by strong ambient light in summer.

Original languageEnglish
Pages (from-to)1617-1627
Number of pages11
JournalPolar Biology
Volume32
Issue number11
DOIs
Publication statusPublished - 2009 Oct

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Keywords

  • Antarctica
  • Diving observation
  • Ecophysiology
  • Photosynthesis
  • Phytobenthos

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)

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