Oxygen constraints at the primary production - consumer interface: the aquatic keystone species Daphnia and its stoichiometric regulation

初级生产-消费者界面的氧气限制：水生关键物种水蚤及其化学计量调节

• 批准号: 165038252
• 负责人: Professor Dr. Alexander Wacker
• 金额: --
• 依托单位: Professur für Tierökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/165038252?language=en
• 关键词: Oxygen; constraints; primary; production; consumer

Anthropogenically increased nutrients and enhanced water temperatures (global change) are predicted to promote the occurrence of oxygen deficiencies and cyanobacterial blooms, both with the well-known detrimental effects on aquatic ecosystems and water quality. Cyanobacteria lack essential fatty acids and sterols, and are of poor food quality for algae-grazing zooplankton such as the dominant grazer and keystone species Daphnia. When occurring simultaneously, the negative effects of oxygen deficiency and low-quality blooms enhance each other because daphnids that usually control the blooms face the dilemma that under low oxygen concentrations they cannot compensate for poor food quality by higher respiration rates. However, they might enhance the assimilation of limiting dietary compounds or lessen the assimilation of other dietary ingredients in excess or increasing their excretion. We know too little about potential constraints by low oxygen of such stoichiometric regulation to judge its relevance under field conditions. Therefore, under different oxygen conditions the stoichiometric regulation of assimilation, respiration and excretion at different food qualities and quantities shall be investigated by carrying out life history experiments and using 14C radio-labelled diets to track the flow of carbon. This will improve our understanding of Daphnia’s response to changing environmental oxygen, temperature, food concentration and quality, and makes it possible to predict future reactions of the Daphnia-mediated interface between primary production and consumers.

人为增加的营养和提高的水温（全球变化）预计将促进缺氧和蓝藻水华的发生，这两者都对水生生态系统和水质产生众所周知的有害影响。蓝细菌缺乏必需脂肪酸和甾醇，对于食藻浮游动物（如优势食草动物和关键物种水蚤）来说，食物质量很差。当同时发生时，缺氧和低质量的花朵的负面影响相互增强，因为通常控制花朵的水蚤面临的困境是，在低氧浓度下，它们不能通过更高的呼吸速率来补偿食物质量差。然而，它们可能会增强限制性膳食化合物的同化，或减少过量其他膳食成分的同化或增加其排泄。我们知道太少的潜在限制低氧的这种化学计量调节判断其相关性在现场条件下。因此，在不同的氧气条件下，在不同的食物质量和数量的同化，呼吸和排泄的化学计量调节应通过进行生活史实验和使用14C放射性标记的饮食来跟踪碳的流动进行研究。这将提高我们对水蚤对环境氧气、温度、食物浓度和质量变化的反应的理解，并使预测水蚤介导的初级生产和消费者之间界面的未来反应成为可能。