Quantifying and partitioning spatiotemporal variability in secondary production and trophic transfer efficiency in pelagic marine ecosystems

量化和划分中上层海洋生态系统二次生产和营养转移效率的时空变化

• 批准号: RGPIN-2020-07077
• 负责人: Dower, John
• 金额: $ 2.4万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745683
• 关键词: Quantifying; partitioning; spatiotemporal; variability; secondary

This research aims to measure two factors that, although critically important to understanding marine food chains, have rarely been measured in Canadian waters. The first is known as "secondary production", which is the rate at which zooplankton are produced. Zooplankton are tiny animals (mostly less than 1 cm in size) that feed on single-celled plants (called "phytoplankton") at the base of most marine food chains. Zooplankton are consumed by larger animals - including many young and adult fish, certain marine mammals, and even seabirds. The second factor is referred to as the "trophic transfer efficiency" (TTE). In short, this is an estimate of how much energy is transferred between different levels of the food chain (e.g. from phytoplankton to zooplankton). The higher the TTE the more energy that is transferred up the food chain, and the greater the amount of fish, marine mammals, etc. that can be supported. These two factors are essential components that underlie the mathematical models that oceanographers use to study marine food webs, and to predict how such food webs may change in the future. However, mainly for technical reasons, neither factor is measured directly in the ocean. Instead, modelers have relied on numbers drawn from simplified lab experiments or theoretical studies. My lab has developed a method to directly measure secondary production, based on measuring an enzyme (called chitobiase) that most zooplankton release into the water as they grow. When put together with measures of the rate of phytoplankton growth (known as "primary production" - something that oceanographers have been able to do since the 1960s), we have been able to produce the first direct estimates of TTE in a natural field setting. Over the next five years we will expand our work to begin exploring how secondary production and TTE vary between locations and at different timescale (i.e. seasonally, between years, etc.) off Canada's west coast. The data we generate will be used by researchers at Fisheries and Oceans Canada (and elsewhere) to refine their ecosystem models and improve their ability to forecast how Canada's marine resources may respond to changing ocean climates in the future.

这项研究旨在测量两个因素，尽管这两个因素对于理解海洋食物链至关重要，但在加拿大水域很少被测量。第一个被称为“二次生产”，即浮游动物的生产速度。浮游动物是微小动物（大多小于 1 厘米），以大多数海洋食物链底部的单细胞植物（称为“浮游植物”）为食。浮游动物被大型动物吃掉，包括许多幼鱼和成鱼、某些海洋哺乳动物，甚至海鸟。第二个因素称为“营养转移效率”（TTE）。简而言之，这是对食物链不同层次之间（例如从浮游植物到浮游动物）转移多少能量的估计。 TTE 越高，食物链上转移的能量就越多，可以支持的鱼类、海洋哺乳动物等的数量就越多。这两个因素是海洋学家用来研究海洋食物网并预测此类食物网未来如何变化的数学模型的重要组成部分。然而，主要由于技术原因，这两个因素都没有在海洋中直接测量。相反，建模者依赖于从简化的实验室实验或理论研究中得出的数据。我的实验室开发了一种直接测量二次生产的方法，该方法基于测量大多数浮游动物在生长时释放到水中的酶（称为壳二糖酶）。当与浮游植物生长速率的测量（称为“初级生产”——海洋学家自 20 世纪 60 年代以来就能够做到这一点）结合起来时，我们已经能够在自然野外环境中对 TTE 进行首次直接估计。在接下来的五年中，我们将扩大工作范围，开始探索加拿大西海岸附近不同地点和不同时间尺度（即季节性、年份等）的二次生产和 TTE 如何变化。我们生成的数据将被加拿大渔业和海洋局（以及其他地方）的研究人员用来完善他们的生态系统模型，并提高他们预测加拿大海洋资源如何应对未来海洋气候变化的能力。