UVB effects on a plankton community: results from a large-scale enclosure assay

被引:24
作者
Laurion, I
Lean, DRS
Vincent, WF
机构
[1] Univ Laval, Dept Biol, Ste Foy, PQ G1K 7P4, Canada
[2] Univ Laval, Ctr Etud Nord, Ste Foy, PQ G1K 7P4, Canada
[3] Univ Ottawa, Dept Biol, Ottawa, ON K1N 6N5, Canada
关键词
ultraviolet-B; photosynthesis; phytoplankton; enclosure; temperate lake; Ochromonas; grazing; mixotroph;
D O I
10.3354/ame016189
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
The long-term effects of natural and enhanced ultpaviolet-B (UVB) exposure on picocyanobacteria, size-fractionated chlorophyll a (chl a), primary production (photosynthesis-irradiance parameters) and grazing activity on phytoplankton were investigated over a 20 d period in a mesotrophic lake in central Ontario, Canada. Large volume enclosures (20 000 1) open to the sediments were installed in the Littoral zone and sampled at 6 d intervals. Four radiation treatments were run: UVB-screened giving 0% incident UVB, natural ambient (100% UVB), and 2 lamp-enhanced treatments giving 112% biologically weighted WE (range of 109 to 126% depending on cloud cover) and 118% biologically weighted UVB (114 to 138%). The Light utilization efficiency of the phytoplankton (alpha) decreased under enhanced UVB, but there was no significant decrease in biomass (chl a or cell counts). Populations of the nanoflagellate Ochromonas sp, significantly increased under enhanced UVB; after 20 d the cell concentration of this species was ca 3.6 times higher relative to the natural UVB control. However, differences between treatments in picocyanobacteria, <2 pm chi a, other nanoplanktonic groups, maximum photosynthetic rates, sensitivity to photoinhibition and grazing activity were generally small relative to the variability between duplicate enclosures. These results indicate a low impact of natural and increased levels of incident UVB on the inshore plankton community in this type of lake environment.
引用
收藏
页码:189 / 198
页数:10
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