Investigating marine carbon cycling using fatty acids and their stable carbon isotopes

我小组的研究兴趣包括了解脂质代谢，以便我们可以利用脂质作为追踪碳流的工具。具体来说，我们对脂肪酸（FA）在海洋环境中碳循环和食物网动态研究中的应用感兴趣。FA非常适合这类研究，因为许多膳食FA仅在结构上进行了微小的修改就被纳入了消费者体内，这使得FA作为其来源的指示器或生物标记物很有用。我们建议继续我们正在进行的研究低营养水平的FA从猎物到捕食者的转移，目的是建立一个模型来估计捕食者的饮食。我们将使用来自FA数据的两种不同类型的信息：1)FA配置文件。不同种类的猎物中FA的比例是不同的，并通过轻微的修改传递给消费者，使我们能够从猎物到消费者脂肪储存中追踪这些FA签名；2)特异FA的稳定同位素。被捕食物种的特定FA中的碳同位素分布通常是不同的，并且传递给消费者的变化很小，这使得我们可以使用FA的稳定同位素作为额外的示踪剂。然而，这两种方法都需要研究在捕食者脂肪储存的消化、沉积和动员过程中，FA特征或稳定同位素比率可能发生的细微生化变化。因此，我们建议以大西洋鳕鱼（polachius virens）为模型物种进行一系列的控制饲养实验，以量化可能发生的FA变化。有了对生物化学变化的清晰认识，我们可以利用FA信息构建数学模型来确定鱼类的饲料。然后，这些模型可以作为我们正在开发的更广泛的碳追踪技术的一部分应用于研究许多不同环境中的食物网结构。具体来说，我们感兴趣的是将这些模型应用于最易受气候变化影响的生态系统，如白令海和西北大西洋，以检测碳循环随时间的变化。

The research interests of my group involve understanding lipid metabolism so that we can use lipids as a tool to trace carbon flow. Specifically, we are interested in the use of fatty acids (FA) in the study of carbon cycling and food web dynamics in the marine environment. FA are well suited to such studies because many dietary FA are incorporated into consumers with only minor modification to structure, making FA useful as indicators or biomarkers of their source. We propose to continue our ongoing work investigating the transfer of FA from prey to predators at low trophic levels, with the aim of developing a model to estimate predator diets. We will use two different types of information from FA data: 1) FA profiles. The proportions of FA in different species of prey are distinct and are passed to consumers with minor modification, allowing us to trace these FA signatures from prey to consumer fat stores; and 2) stable isotopes of specific FA. The distribution of carbon isotopes within specific FA of prey species are often different and are also passed to consumers with little change, allowing us to use stable isotopes of FA as an additional tracer. Both approaches, however, require investigation into the subtle biochemical changes that may occur in FA signatures or stable isotope ratios with digestion, deposition and mobilization in predator's fat stores. Thus, we propose to carry out a series of controlled feeding experiments using Atlantic pollock (Pollachius virens) as a model species to quantify any alterations in FA that may occur. With a clear understanding of biochemical changes, we can construct mathematical models to determine fish diets using FA information. These models can then be applied as part of a broader carbon-tracing technique that we are developing for application to the study of food web structure in a number of different environments. Specifically, we are interested in applying these models to ecosystems most susceptible to effects of climate changes, such as the Bering Sea and the northwest Atlantic, to detect changes in carbon cycling over time.