Grant: Discovery Grants Program - Individual

This study is all about taking it to the next level in marine food web research, both in terms of what we are probing and how we are doing it. We will see how lipids are transferred from one level of the food web to the next level up and we will use a new very sophisticated analytical approach to measuring entire suites of lipid compounds. Lipids are essential for life, providing energy, structure to cell membranes, and chemical messengers in organisms. Lipids are made biologically by processes under the influence of factors such as diet and temperature.* Aquatic ecosystems occupy the largest part of the biosphere, and lipids in those systems provide the densest form of energy. Lipid dynamics can also strongly influence pollutant accumulation in marine food webs. Among the lipids, certain essential fatty acids such as long-chain omega-3 polyunsaturated fatty acids (PUFA), and sterols such as cholesterol are considered to be drivers of ecosystem health and stability. This study is a continuation of our ongoing program to investigate the importance of lipids in marine organisms and the cycling of these carbon-rich compounds in marine food webs.*Objectives* My long-term goal is to quantify production, transport, ultimate fate and effects of lipids in the marine environment, especially in the context of global change.*Here my first objective is to compare lipid production, transport and fate in understudied cold and warm water ecosystems. With three of my current students and one new one we will examine four highly contrasted food webs: 1) The deep-sea food web located in the northwest Atlantic off Newfoundland, 2) Subarctic rhodolith beds off Newfoundland, 3) The subtropical euphausiid food web in the Gulf of California, and 4) The subtropical tuna food web in the southwest Pacific Ocean. My second objective is to examine the effect of changes in diet, temperature and acidity on the chemical composition of biological membranes with a new student, using new analytical technology. In tandem with my first objective, my third objective is to determine if there is an alternative biosynthetic pathway that is in operation in marine ecosystems for synthesizing critical PUFA. Knowing the origin of essential fatty acids present in deep and/or cold ecosystems is particularly important in the context of global change.*Impact* The characterization of energy flow in ecosystems is one of the main goals of ecology, and the analysis of how different levels of the food web interact is key to quantifying its flow. Lipids are central to these studies yielding more than twice the amount of energy per gram than proteins or carbohydrates, and providing essential fatty acids and phytosterols and cholesterol as well as a means to quantify the connections through detailed analysis of lipid compounds. Thus determination of the origin, abundance, and transfer of lipids will aid in effective monitoring of the sustainability and health of marine ecosystems.*