Linking phytoplankton biodiversity and food quality effects in herbivore zooplankton

该项目的目标是将生物多样性效应纳入食品质量研究，以了解水生消费者对变化的环境条件和伴随的物种丰富度变化的反应。本文以淡水keystone草食动物水蚤为模式生物，从浮游植物猎物的形态、元素和生化特性出发，揭示浮游植物多样性对水生食用者生活史性状的有益或有害影响。这包括需要更好地理解(a)食物质量的异质性（形态和生物/化学成分）如何与猎物多样性联系起来，以及(B)在不同多样性群落中生长的浮游植物物种之间的相互作用如何产生食物质量的异质性。我们通过揭示(I)水蚤对不同猎物物种丰富度的行为和生理反应（即摄食、消化、同化、呼吸、排泄、生产和繁殖），以及（II）浮游植物的形态、元素和生化特性在触发更高猎物多样性对水蚤性能的可能影响中的作用，来解决这一问题。这就需要了解浮游植物在不同群落中相互作用的形态、元素和生化特性的变化和物种特异性调整。此外，我们还关注了可能影响浮游植物多样性的环境因素的变化，如光照和养分有效性。我们通过实验室实验来实现我们的目标。研究上述机制将有助于更好地从机制上理解浮游植物多样性对水生消费者表现的影响。我们将深入了解浮游植物（初级生产者）群落异质性的起源，并将提高我们对基本生物/化学物质生物利用度变化过程的认识。这些结果将提高我们了解重要水生消费者对环境条件变化和物种丰富度变化的反应的能力。此外，它将有助于建立由脂肪酸和固醇缺乏引起的生化限制的预测框架。这些框架将特别考虑初级生产者和消费者之间营养相互作用的生化异质性。

The objective of the submitted project is to integrate biodiversity effects into food quality research in order to understand responses of aquatic consumers to changing environmental conditions and accompanied changes in species richness. We aim to reveal beneficial or detrimental effects of phytoplankton diversity on life history traits of aquatic consumers by considering morphological, elemental and biochemical properties of the phytoplankton prey, using the freshwater keystone herbivore Daphnia as model organism. This includes the need of a better understanding of (A) how heterogeneity in food quality (morphology and bio/chemical composition) is linked to prey diversity, and (B) how heterogeneity in food quality is generated by interactions among phytoplankton species growing in differently diverse communities. We approach this by unraveling (I) the behavioural and physiological response of Daphnia (i.e., ingestion, digestion, assimilation, respiration, excretion, production, and reproduction) to different prey species richness levels, and (II) the role of morphological, elemental and biochemical properties of phytoplankton, which originates from a more diverse community composition, in triggering possible effects of higher prey diversity on Daphnia performance. This demands knowledge of the variation and species-specific adjustments in morphological, elemental and biochemical properties of phytoplankton interacting in differently diverse communities. Furthermore, we focus on changes in environmental factors such as light and nutrient availability that may affect the phytoplankton diversity. We address our aims by using laboratory experiments. Studying the above described mechanisms will lead to a better mechanistic understanding of the consequences associated with chances in phytoplankton diversity for the performance of aquatic consumers. We will gain insights on the origin of heterogeneity in the phytoplankton (primary producers) community and will enhance our knowledge on processes involved in changes in the bioavailability of essential bio/chemicals. The results will improve our ability to understand responses of important aquatic consumers to changing environmental conditions and accompanied changes in species richness. Further it will help to enable the establishment of predictive frameworks for biochemical limitations induced by deficiencies in fatty acids and sterols. These frameworks will specifically consider the biochemical heterogeneity in trophic interactions between primary producers and consumers.