Effects of nitrogenous compounds and phosphorus on the growth of toxic and non-toxic strains of Microcystis during cyanobacterial blooms
Effects of nitrogenous compounds and phosphorus on the growth of toxic and non-toxic strains of Microcystis during cyanobacterial blooms
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DOI：
10.3354/ame01445
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发表时间：
2010-01-01
影响因子：
1.4
通讯作者：
Gobler, Christopher J.
中科院分区：
文献类型：
--
作者：
Davis, Timothy W.;Harke, Matthew J.;Gobler, Christopher J.
自二十世纪中叶以来，沿海水生生态系统中营养物质的输送速率和有害藻华(HAB)的发生频率都有所加强。最近的研究表明，氮(N)或磷(P)可以限制淡水系统中的初级生产力，而微囊藻能够利用无机和有机形式的氮。本研究量化了微囊藻毒素合成酶基因(McyD)和核糖体RNA基因(16S)，以评估不同的营养来源如何影响自然水华期间有毒和无毒的微囊藻菌株的生长。在本研究期间，在美国东部的两个不同的生态系统中观察到了密集的微囊藻水华(>；10(6)细胞当量L(-1))：潮汐支流和富营养化湖泊。在这两个系统中，在营养改良实验中，所有微囊藻种群受到N的刺激比P更频繁。微囊藻有毒菌株的丰度通过营养强化(83%的实验)比非有毒菌株(58%的实验)更频繁地增加，这表明有毒菌株可能对这两种营养物质都有更大的需求。此外，无机氮(67%的实验)比有机氮(8%的实验)更能提高有毒微囊藻菌株的丰度，而无毒的菌株被有机氮(50%的实验)比无机氮(25%的实验)更频繁地刺激。无机磷增加有毒微囊藻菌株的丰度比非有毒菌株更频繁(分别为42%和33%)。因此，有毒微囊藻的优势度可能同时受到营养物质浓度和种类的影响，较高浓度的无机N和/或P可能促进以有毒菌株为主的水华，并可能产生较高的微囊藻毒素浓度。
Since the mid-twentieth century, both nutrient delivery rates and the frequency of harmful algal blooms (HABs) in coastal aquatic ecosystems have intensified. Recent studies have shown that nitrogen (N) or phosphorus (P) can limit primary production in freshwater systems, and Microcystis is able to utilize both inorganic and organic forms of N. The present study quantified the microcystin synthetase gene (mcyD) and the ribosomal RNA gene (16S) to assess how various nutrient sources affected the growth of toxic and non-toxic strains of Microcystis during natural blooms. During the present study, dense Microcystis blooms (>10(6) cell equivalents l(-1)) were observed within 2 contrasting ecosystems in the eastern USA: a tidal tributary and a eutrophic lake. In both systems, all Microcystis populations were stimulated by N more frequently than P during nutrient amendment experiments. The abundance of toxic strains of Microcystis was enhanced by nutrient enrichment more frequently (83% of experiments) than non-toxic strains (58% of experiments), suggesting that toxic strains may have a greater demand for both nutrients. Furthermore, abundances of toxic strains of Microcystis were enhanced by inorganic N more frequently (67% of experiments) than organic N (8% of experiments), while non-toxic strains were stimulated by organic N (50% of experiments) more frequently than inorganic N (25% of experiments). Inorganic P increased abundances of toxic strains of Microcystis more frequently than non-toxic strains (42 and 33% of experiments, respectively). Therefore, the dominance of toxic Microcystis may be influenced by both the concentration and species of nutrients, with higher concentrations of inorganic N and/or P likely promoting blooms dominated by toxic strains and potentially yielding higher microcystin concentrations.