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11.
Abundance of picophytoplankton in the halocline of a meromictic lake, Lake Suigetsu, Japan 总被引:1,自引:0,他引:1
Mari Okada Yukiko Taniuchi Akio Murakami Shinichi Takaichi Shinya Ohtake Kaori Ohki 《Limnology》2007,8(3):271-280
Numerous (0.5 to 4.8 × 105 cells/ml), small phytoplankton (smaller than 0.5–1 × 1–2 μm in cell size, picophytoplankton) were distributed in the halocline
(depth 2–12 m, 4–14 practical salinity units) of the saline meromictic lake, Lake Suigetsu (35°35′ N, 135°52′ E), located
in the central part of the coast of Wakasa Bay along the Japan Sea in Fukui Prefecture, Japan. Vertical distribution of phytoplankton
revealed that the maximum number of picophytoplankton was always observed near or a little deeper than the oxic-anoxic boundary
layer (depth 5–6 m); they were dominant phytoplankton in the water layer deeper than the oxic-anoxic boundary from July to
late September 2005. Spectral analysis of autofluorescence emitted from the particle fractions smaller than 5 μm measured
with a spectrofluorometer and from individual cells measured with a microscope photodiode array detector revealed that the
major component of picophytoplankton was phycoerythrin-rich, unicellular cyanobacteria (picocyanobacteria). Eukaryotic phytoplankton
about 2.5 μm in diameter were also found, but the numbers were low. Fluorescence intensity of chlorophyll a at 685 nm (room temperature) emitted from the particle fractions smaller than 5 μm was increased by the addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea.
These observations indicated that at least some picophytoplankton had a functional photosystem II in the halocline where sulfide,
the potential inhibitor of oxygenic photosynthesis, was always present. The large abundance together with their physiological
potency suggest that picophytoplankton are one of the important primary producers in the halocline of Lake Suigetsu.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
12.
C. Gugliandolo F. Italiano T. L. Maugeri S. Inguaggiato D. Caccamo J. P. Amend 《Geomicrobiology journal》2013,30(1):105-117
The relationship between fluid geochemistry and microbial communities was investigated for shallow (< 25 m) submarine hydrothermal vents in the Aeolian Islands (Southern Italy). Thermal waters, gases, and deposits of white filamentous material were collected from 11 sites. The geochemical analyses showed a magmatic component was present in all sampled fluids. The total microbial abundances, evaluated as direct counts of picoplanktonic cells (ranging from 0.2 to 2 mu m in diameter), were between 1.55 107 and 4.18 108 cells per liter. Picophytoplankton (total autofluorescent cells) ranged from 9.6 105 to 7.88 106 cells per liter. Yellow-orange autofluorescent prokaryotes belonging to the cyanobacteria were more abundant than red autofluorescent eukaryotic cells. Chemolithoautotrophic, sulfur-oxidizing, rod-shaped Bacteria were isolated from venting water samples and identified as Thiobacillus -like. Microscopic examination of the white mat deposits showed the presence of filamentous microorganisms. 相似文献
13.
Toshi Nagata 《Ecological Research》1986,1(2):207-221
The seasonal changes in the size-fractionated chlorophylla concentrations (<3 μm, 3 to 25 μm, and >25 μm) were investigated at a pelagic site of the north basin of Lake Biwa during
June to December 1985. Autofluorescing plankton cells in the <3-μm fractions were also examined using the fluorescein isothiocyanate
staining epifluorescence microscopic technique. The <3-μm phytoplankton (usually dominated by chroococcoid cyanobacteria except
for a few cases dominated by small eukaryotes) showed a clearly different pattern of seasonal change compared with the larger
fractions. That is, from August to early September, chlorophylla of the larger fractions declined considerably, while the <3-μm chlorophylla did not decrease significantly. Moreover, cyanobacterial cell density in the <3-μm fraction showed a maximum value (2–3.5×105 cells·ml−1) during this period. The relative contribution of the <3-μm chlorophylla to the total chlorophylla increased from <5% to 45% during the course of this change. No clear vertical trend in the distribution and composition of
the <3-μm phytoplankton was found, except that relatively large cyanobacteria (>4 μm3) appeared at a depth of 15m but not at 0,5 and 10 m from late July to August. These large cells were also found in November
and December. The drastic seasonal change of phytoplankton size structure occurring in this basin was discussed in relation
to grazing, nutrient depletion and sinking.
Contribution from Otsu Hydrobiological Station, Kyoto Univeristy (No. 308, foreign language series). 相似文献