TAXONOMIC SHIFT OVER A PHOSPHORUS GRADIENT AFFECTS THE STOICHIOMETRY AND FATTY ACID COMPOSITION OF STREAM PERIPHYTON
TAXONOMIC SHIFT OVER A PHOSPHORUS GRADIENT AFFECTS THE STOICHIOMETRY AND FATTY ACID COMPOSITION OF STREAM PERIPHYTON
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DOI：
10.1111/jpy.13060
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发表时间：
2020-11-08
影响因子：
2.9
通讯作者：
Fink, Patrick
中科院分区：
文献类型：
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作者：
Iannino, Alessandra;Vosshage, Alexander Tim Ludwig;Fink, Patrick
河流生态系统的磷富集通常会增加底栖动物的初级生产力，但富营养化对食草动物附生植物营养质量的影响尚不清楚。在短时间内，高磷输入可能导致 C:P 比率降低和附生植物必需脂肪酸含量升高，这两者都被认为是食草动物食物质量的重要决定因素。然而，营养富集可能会改变附生植物的分类组成，并有利于不太适口的藻类类群的生长。在这项研究中，附生生物在5至100μg P的溶解磷有效性梯度下生长。 L-1，研究富营养化对附生生物分类、C:N:P 化学计量和脂肪酸组成的影响。 1个月后，贫营养条件下生长的附生生物主要由硅藻组成（约86%）。随着磷利用率的增加，硅藻逐渐被叶绿藻和蓝藻所取代，而它们是富营养化条件下的主要分类单元。出乎意料的是，附生生物C:P比率随着磷供应量的增加而增加，从贫营养条件下的大约280上升到100μg时的大约790。 L-1，反映了与硅藻相比，叶绿藻和蓝藻每单位同化磷产生更多生物量的趋势。相对于生物量的必需多不饱和脂肪酸的附生生物含量与磷利用率呈单峰关系，并在中等磷水平时达到峰值，这可能是分类学和营养效应的结果。我们的结果表明，磷驱动的淡水生态系统富营养化可能会因分类分类而恶化附生植物的营养质量，这可能进一步导致食草动物的生长和繁殖下降。
Phosphorus enrichment of stream ecosystems generally increases primary production in the benthos, but the consequences of eutrophication for the nutritional quality of periphyton for grazers are less clear. On short timescales, high phosphorus inputs may lead to reduced C:P ratios and high essential fatty acid contents of periphyton, which are both considered important determinants of food quality for grazers. However, nutrient enrichment may alter the taxonomic composition of periphyton and favor the growth of less palatable algal taxa. In this study, periphyton was grown under a gradient of dissolved phosphorus availability from 5 to 100 mu g P . L-1, to investigate eutrophication effects on periphyton taxonomy, C:N:P stoichiometry, and fatty acid composition. After 1 month, periphyton grown under oligotrophic conditions was mainly composed of diatoms (similar to 86%). With increasing phosphorus availability, diatoms were gradually outcompeted by chlorophytes and cyanobacteria, which were the predominant taxon under eutrophic conditions. Unexpectedly, periphyton C:P ratios increased with greater phosphorus supply, from similar to 280 under oligotrophic conditions up to similar to 790 at 100 mu g . L-1, reflecting a tendency of chlorophytes and cyanobacteria to produce more biomass per unit of assimilated phosphorus compared to diatoms. Periphyton content of essential polyunsaturated fatty acids relative to biomass followed a unimodal relationship with phosphorus availability and peaked at intermediate phosphorus levels, likely as a result of both taxonomic and nutrient effects. Our results demonstrate that phosphorus-driven eutrophication of freshwater ecosystems may worsen periphyton nutritional quality due to taxonomic sorting, which may further lead to lower growth and reproduction of herbivores.