Herbivory in aquatic omnivores: effects of climate change

General context

Most aquatic herbivores that consume aquatic plants are in fact omnivorous. As most animal food contains higher nutrient concentrations than plants, the question is why they eat plants and under which conditions. This may be due to environmental conditions. For cold-blooded animals the ambient temperature is very important in determining their nutrient and energy requirements, which may affect their diet selection. Furthermore, temperature also determines how fast plants grow, which in turn may affect the nutrient concentrations and thus food quality of the plants themselves.

Does temperature affect animal food requirements and digestion efficiency and thus food preference? Does temperature affect plant growth rates and their quality as food for animals? These are very basic questions, but little is known about herbivory in aquatic omnivores so there is a lot to discover in this field of research.

Project outline

Food choice experiments with gammarus, snails or crayfish are possible to test their preference of animal versus plant food and the importance of nutrient concentration in the food items at different temperatures. These tests will be performed either in short-term feeding trials or in longer term experiments where we measure food selection using stable isotopes. Another possibility is to perform plant growing experiments at different temperatures to test the impact on their growth rates and nutrient concentrations.

Duration (indicative)

4-9 Months.