Grant: Discovery Grants Program - Individual

This program of research is all about taking it to the next level in marine food web research, both in terms of what we are studying and how we are doing it. We will study 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 biologically synthesized 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 and sterols are considered to be drivers of ecosystem health and stability. This research 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 ecosystems. Objectives      My long-term goal is to quantify production, transport, 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-water ecosystems. We will use lipids to apportion sources quantitatively, to identify nutritional relationships and to quantify food quality in three highly contrasted food webs in the Labrador Sea and coastal Newfoundland. My second objective is to examine the effect of changes in diet, temperature and acidity on the chemical composition of biological membranes using new analytical technology. Lipids are essential components of membranes, and we will examine responses to perturbations using mass spectrometry. We will use carefully controlled Arctic cod and Atlantic salmon feeding experiments at different temperatures. We will also look at the combined effect of increasing temperature and ocean acidification in phytoplankton culture experiments. 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 sterols 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. Lipid research with Atlantic salmon will also help to maximize cultured fish health and the nutritional value of the final product.