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Grazer control of benthic algal biomass: The role of food quality on different levels of spatial organization

放牧者对底栖藻类生物量的控制：食物质量对不同层次空间组织的作用

基本信息

批准号：
319533181
负责人：
Professor Dr. Eric von Elert, Ph.D., since 4/2019
金额：
--
依托单位：
Department Fließgewässerökologie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/319533181?language=en
关键词：
Grazer control benthic algal biomass

项目摘要

In food webs, both bottom-up (i.e., resources) and top-down (i.e., feeding by next trophic level) factors control the biomass on intermediate trophic levels such as benthic algal biofilms (periphyton). Both mechanisms were demonstrated to be significant with, however, strong variations in the strength of top-down control in different natural settings. Factors that determine the strength of top-down control are as yet poorly understood. The central hypothesis of this project is that the strength of top-down control of periphyton is determined by the food quality of the algae, which is in turn regulated by allocation of essential resources (nutrients, energy). In the case of spatial explicit communities such as periphyton, the food quality shows remarkable spatial heterogeneity. This, together with the corresponding behavioural adaptations of the grazers, is probably of particular relevance in the control of periphyton biomass, although these factors have so far rarely been considered. Here we will test this hypothesis on different scales and complexity levels in both highly controlled laboratory experiments and field-related mesocosm experiments. This includes the homogenous local patch size, the multi-patch level with spatial heterogeneity and the choice for gazers as well as a high level of complexity under consideration of growth and migration behaviour of grazers in mesocosm experiments. On these levels, resource allocation (limiting nutrient P; light energy) will be manipulated and grazing control of periphyton will be quantified via (i) flux of matter between algae and grazers and (ii) reduction of periphyton biomass by grazers in relation to grazer-free control. Overall, this project will reveal mechanisms how the strength of top-down pressure on periphyton is regulated and will contribute to understand the control of eutrophication of natural surface waters.

在食物网中，自下而上（即，资源）和自顶向下（即，由下一个营养级喂养）因素控制中间营养级的生物量，例如底栖藻类生物膜（附着生物）。这两种机制被证明是显着的，但是，在不同的自然环境中，自上而下的控制强度的强烈变化。决定自上而下控制强度的因素还知之甚少。该项目的中心假设是，自上而下控制的附着生物的强度是由藻类的食物质量决定的，而藻类的食物质量又受到基本资源（营养物质、能量）分配的调节。在空间显性群落如附着生物的情况下，食物质量表现出显著的空间异质性。这一点，再加上相应的行为适应的食草动物，可能是特别相关的控制附着生物量，虽然这些因素迄今很少被考虑。在这里，我们将测试这一假设在不同的规模和复杂程度的高度控制的实验室实验和现场相关的围隔实验。这包括均匀的本地补丁大小，多补丁水平与空间异质性和选择的gazers，以及一个高层次的复杂性下考虑的生长和迁移行为的食草动物在围隔实验。在这些水平上，资源分配（限制养分P，光能）将被操纵和放牧控制的附生生物将被量化通过（i）藻类和食草动物之间的物质通量和（ii）减少的附生生物生物量的食草动物在无食草动物的控制。总的来说，这个项目将揭示机制，自上而下的压力对附着生物的强度是如何调节的，并将有助于了解自然表面沃茨富营养化的控制。