Understanding trophic links between marine plankton to consumers to improve assessments of UK pelagic habitats

浮游植物负责全球50%的光合作用生产力，循环养分以维持我们海洋中的生命。即使在浮游植物的微观尺寸范围内，也有一个巨大的尺寸范围，从2微米到100微米。最小的浮游植物被称为浮游植物，它们的大小不到2微米，可占英国海水浮游植物生物量的55%，适应性很强。它们由数千种不同的物种组成，但有些类型，尤其是蓝藻，可以通过一种叫做流式细胞术的方法，根据它们的大小和光合色素，进行很好的研究。蓝藻可以在低营养环境中茁壮成长，并且在食物链的每个阶段与较弱的能量转移有关。下一个尺寸是纳米浮游植物，大小在2-20微米之间，更复杂，同样由数千种物种组成，有些类型可以用流式细胞术研究，而另一些则用显微镜计数。较大的浮游植物被称为微型浮游植物。浮游动物是吃浮游植物的小动物或原生动物，被称为初级消费者。它们依次被小鱼吃掉。微型浮游植物和浮游动物在显微镜下更容易计数，因为它们更容易看到，并且用于官方政府对海洋健康的可持续性评估，以确保大型海洋生物从浮游植物或浮游动物中获得足够的食物。目前小型浮游植物不包括在这些评估中，因为它们的监测不太普遍。最近的几项研究表明，英国水域的浮游植物和浮游动物正在发生变化。在西英吉利海峡，小型蓝藻浮游植物在过去50年的夏季一直在增加。与此同时，主要的浮游动物，如被称为桡足类的小型甲壳类动物，在夏季同期减少了50%。它们通常以浮游植物为食，令人担忧。众所周知，浮游生物的大小可以影响能量在食物网中向上移动到鱼类和海洋哺乳动物的数量，较小的浮游植物与较少的能量转移有关。较小的浮游植物和浮游动物之间的一个可能联系是它们出现的时间。如果较大的浮游植物生长和高峰较早，这可能与浮游动物或幼鱼的关键生长阶段的时间不匹配。我们的团队已经在小型浮游植物和环境变量之间发现了基于时间的关系，并发现小型浮游植物的生长特征在英国不同的水体中非常一致，使用了一种称为连续小波变换（CWT）的新方法。我们早期对小型浮游植物群和细菌之间相互作用的探索性研究已经证实了这些生物群之间的关系，以及与温度和氮基营养物质等环境变量之间的关系。我们现在的目标是看看CWT是否能识别出海洋食物网中小型浮游植物和大型浮游植物、浮游动物和幼鱼之间基于时间的关系。这种方法以前没有被使用过。最终，我们想建立一个统计模型，看看较小的浮游植物是否会影响较大的海洋生物的生长。此外，我们希望利用这种方法找到关键的关系，这些关系可以很容易地用于衡量官方政府对海洋健康的评估，如OSPAR。

Phytoplankton are responsible for 50% of global photosynthetic productivity, recycling nutrients to sustain life in our oceans. Even within the microscopic size of phytoplankton there is a huge size range, from 2 microns to 100 microns. The smallest phytoplankton are called Picophytoplankton are are less than 2 microns in size and can contribute up to 55% of the phytoplankton biomass in UK marine waters and are very adaptable. They are made up of thousands of different varieties of species, but some types, especially cyanobacteria are well studied using a method called flow cytometry based on their size and photosynthetic pigments. Cyanobacteria can thrive in low nutrient environments and associated with weaker energy transfer at each stage of the food chain. The next size is nanophytoplankton which range from 2-20 microns in size and are more complex, again made up of thousands of species and some types can be studied using flow cytometry whilst others are counted using a microscope. Larger phytoplankton are called microphytoplankton. Zooplankton are tiny animals or protozoa that eat phytoplankton and known as primary consumers. They are eaten in turn by young fish. Microphytoplankton and Zooplankton are easier to count on a microscope because they are easier to see and are used in official government assessments of marine health for sustainability to ensure larger marine organisms are getting enough food from phytoplankton or zooplankton. Currently small phytoplankton are not included in these assessments because their monitoring is less universal.Several recent studies show Phytoplankton and Zooplankton are changing in UK waters. In the Western English Channel, small-sized cyanobacterial phytoplankton have been increasing in the summer seasons over 50 years. At the same time, key zooplankton such as small crustaceans called copepods, have declined by 50% over the same period in summer. They normally feed on phytoplankton and is a concern. It is known that size of plankton can affect how much energy moves up the food web to fish and marine mammals, with smaller phytoplankton associated with less energy transfer. One possible link between smaller phytoplankton and zooplankton is the timing of their appearance. If larger phytoplankton are growing and peaking earlier this may not match the timing of zooplankton or young fish key growth stages. Our team has already found time-based relationships within smaller phytoplankton and environmental variables and found that smaller phytoplankton growth characteristics are quite consistent across different UK water bodies using a novel method called Continuous wavelet transformation(CWT). Our earlier exploratory studies of interactions even within small phytoplankton aggregate groups and bacteria have confirmed relationships within these biological groups and also with environmental variables like temperature and nitrogen-based nutrients. Our aim now is to see if CWT can identify time-based relationships across the marine food web from smaller phytoplankton and larger phytoplankton, zooplankton and young fish. This approach has not been used before. Ultimately we want to create a statistical model to see if smaller phytoplankton affect the growth of larger marine organisms. Additionally we want to use this approach to find key relationships that can easily be used to measure food webs in official governmental assessments of marine health, such as OSPAR.