Role of suspended sediments and mixing in reducing photoinhibition in the bloom-forming cyanobacterium Microcystis.
Role of suspended sediments and mixing in reducing photoinhibition in the bloom-forming cyanobacterium Microcystis.
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DOI：
10.4236/jwarp.2012.412119
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发表时间：
2012-01-01
期刊：
影响因子：
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通讯作者：
Krause, A. E.
中科院分区：
文献类型：
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作者：
Chaffin, J. D.;Bridgeman, T. B.;Krause, A. E.
有毒的蓝藻水华正在成为一个全球性问题。蓝藻水华发展的先前研究已经研究了高营养浓度如何促进蓝藻优势，以及正浮力如何提供优于下沉浮游植物的生态优势。负责将营养物加载到湖泊的支流通常同时提供高浓度的悬浮沉积物。高浓度的悬浮沉积物也可能通过影响环境光气候、减少光损害和提高光合作用效率而影响水华。我们研究了沉积物和垂直混合的影响，在潜在的减少光损伤微囊藻的光合参数和色素含量在西部湖伊利在2008年的水华和实验室实验。光合效率随含沙量的增加而增加。单位干重的光保护类胡萝卜素色素含量随沉积物浓度的增加而降低，而捕光色素叶绿素a和藻蓝蛋白则随沉积物浓度的增加而增加。这些结果表明，悬浮沉积物减少微囊藻的光抑制。此外，光合作用的损害更高时，微囊藻集中在表面相比，混合水柱。除了光合作用测量外，还记录了微囊藻丰度和光照的测量。最大的微囊藻丰度在伊利湖记录在光限制条件下，提供微囊藻的生理和生态效益，减少光抑制和增加微囊藻的优势，通过浮力光竞争。减少蓝藻水华的努力可能包括减少悬浮沉积物负荷与减少营养负荷相结合。
Toxic cyanobacterial blooms are becoming a global problem. Previous research of cyanobacterial bloom development has examined how high nutrient concentrations promote cyanobacteria dominance, and how positive buoyancy provides an ecological advantage over sinking phytoplankton. Tributaries responsible for loading nutrients into lakes often simultaneously contribute high concentrations of suspended sediments. High concentrations of suspended sediments may also influence blooms by affecting the ambient light climate, reducing photodamage, and increasing the efficiency of photosynthesis. We examined the effects of sediments and vertical mixing in potentially reducing photodamage to Microcystis by measuring photosynthetic parameters and pigment content of Microcystis in western Lake Erie during the 2008 bloom and in laboratory experiments. Photosynthetic efficiency increased with increasing sediment concentration in the lake and laboratory experiment. Content of photo-protective carotenoid pigments per dry weight decreased with increasing sediment concentrations, while the light-harvesting pigments, chl a and phycocyanin, increased with sediments. These results indicate that suspended sediments reduce photoinhibition for Microcystis. Further, photosynthetic damage was higher when Microcystis was concentrated on the surface compared to a mixed water column. Measurements of Microcystis abundance and light were also recorded, in addition to photosynthetic measurements. Greatest Microcystis abundances in Lake Erie were recorded during light-limiting conditions, which offer Microcystis both physiological and ecological benefits by reducing photoinhibition and increasing Microcystis' advantage in light competition via buoyancy. Efforts to reduce cyanobacterial blooms may include reducing suspended sediments loads in combination with reducing nutrient loading.