PhD Defense Eva Werbrouck

Wednesday, November 30, 2016

On thursday 15 December , Eva Werbrouck will be defending her PhD dissertation. Her research focused on fatty acid dynamics in harpacticoid copepods at the basis of marine food webs.  The PhD is promoted by Prof. Dr. Marleen De Troch and co-promoted by Prof. Dr. Ann Vanreusel. Eva gives us a short abstract below. The defense starts at 16:00 and takes place in the Multimedia room, S9, Campus Sterre. The invitation can be found here.

For a long time, factors regulating food web structure have fascinated ecologists. Especially the carbon flux across the plant-animal interface in aquatic food webs appeared highly variable and the least predictable. Nowadays it is well recognized that not only food quantity but also quality determines the trophic coupling in aquatic ecosystems. In particular, fatty acids are considered essential food ingredients. As the building blocks of fats (lipids), they function not only as a source of metabolic energy, some of them are required for optimal function and health in organisms.        
These complex molecules are better known as ‘omega-3’ fatty acids. Many of our daily food products are enriched in these compounds, they are the key ingredients of many ‘health-pills’ and supermarkets use them to promote fish consumption. Nonetheless, few people are aware that most omega-3 is produced at the basis of aquatic food webs, and more specifically by the microscopically-small, unicellular algae. In turn, they are grazed upon by herbivores and subsequently are consumed and transmitted to organisms higher up the food web. Eventually, they end up in the fish on our plate.    
This doctoral thesis investigated the fatty acid dynamics of harpacticoid copepods as important  herbivores in marine benthic food webs. As first-level consumers, they have direct access to a wide range of algal, dietary fatty acids. In turn, they incorporate, accumulate or modify these dietary fatty acids or, to some extent, synthesize fatty acids de novo. Possibly, all these responses are adaptations to cope with the fluctuating food conditions in their particular habitat. Understanding if, how and why these responses operate in harpacticoid copepods may contribute to a better understanding of food web structure and function.             
To this purpose, copepods were exposed to a range of controlled environmental (diet-temperature) conditions and their fatty acids, associated with storage and structural lipids, were investigated.
Altogether this PhD research had two overarching objectives (1) to compare the lipid (fatty acid) characteristics of harpacticoids from contrasting environments (polar versus temperate) and (2) to investigate specific mechanisms, i.e. fatty acid utilization and retention, accumulation and modification, that shape the fatty acid profile of a temperate harpacticoid copepod and thus allow the successful exploitation of its habitat. The outcomes are further integrated and interpreted in a broader physiological and ecological context.