News & Stories

In our project “Freshwater ectotherms under climate change: the role of phenotypic plasticity in life histories and trophic interactions”, we explore how climate change affects water insects and other invertebrates. Those organisms respond to the temperature changes immediately and their life processes are accelerating. Higher temperatures will change aquatic organisms’ survival, the functioning of individual species and can disturb the food chain. Check this video (only in Czech) made by the Academy of Sciences of the Czech Republic in our lab.

Click here for video (Czech Only)

My name is Julie Egon and I did this 4-month internship as part of my first year of master in Ecology and Sustainable Development at the Catholic University of the West in Angers, France. This internship was carried out within the Department of Ecosystem Biology of the University of Southern Bohemia under the supervision of Julien Mocq, post-doctoral researcher at the University of Southern Bohemia and Patrick Gillet, a professor at the Catholic University of the west, in Angers. On a personal level, I derive from this course many benefits and enriching experiences. This internship allowed me to better understand this environment and to acquire a particular rigor in my work. This was also an opportunity for me to deepen my knowledge of ecology and entomology, two subjects that are close to my heart.

Reference : Egon. J. (2016) Influences of biotic factors on predation on Daphnia magna by Chaoborus obscuripes in an intraguild predation system; M1 thesis; Université Catholique de l’Ouest ; 31pp.
Under the supervision of Dr. J. Mocq

Influences of biotic factors on predation on Daphnia magna by Chaoborus obscuripes in an intraguild predation system

Introduction

IntraGuild Predation (IGP) is an interaction in which a predator, called the top (IG predator), can consume another predator (IG prey), both sharing a common resource called extraguild prey (Polis and McCormick, 1987). It is very common in natural environment and it may have an important impact on the structure of the communities. Some abiotic and biotic variables influence the intensity of intraguild predation, such as extraguild prey density: if this density is high, competition between predators will tend to be low and there will be little IGP (Lucas et al., 1998).

My name is Jeff Rouïll and I am currently in master 1 at the University of Tours in France. My internship in the laboratory lasted 4 months under the supervision of Dr. Julien Mocq. The topic of my internship was focused on temperature dependence of activity and metabolism in aquatic invertebrates:

With the current global warming, freshwater ecosystems and its dwelling organisms are threatened. The temperature changes that are expected may alter physiological mechanisms and behaviors in aquatic invertebrates. Therefore, we wanted to determine the impact of temperature on metabolism and activity in various aquatic invertebrate species.

To achieve this objective, we performed measurements of basal metabolism and spontaneous activity of several species of aquatic invertebrates (Aeshna cyanea, Chaoborus obscuripes, Cloeon dipterum, Coenagrion puella, Daphnia magna ...) along a temperature gradient (ranges of temperatures here). For the measurements we use a probe to test the oxygen concentration which allows us to evaluate the basic metabolism. And we use a camera device to film the movements of individuals in an aquarium, to analyze the distance traveled in 10 minutes as a spontaneous activity proxy.

Our results show an increase in oxygen consumption with temperature, which has the effect of increasing energy expenditure. Aeshna -dragonfly- also shows a decrease in activity with temperature unlike Cloeon -mayfly-. The existence of a relationship between basal metabolism and activity was also tested, which allowed us to show a strong negative correlation in Aeshna and a positive correlation for Chaoborus -mosquito-. All of these changes in metabolism and activity are not without consequences, their increases can lead to an increase in search and food intake, increasing energy expenditure and increasing predation risk. There is then a possibility of strong modification in inter-organism relationships such as changes in competition ratios, survival to predation or choice of prey, and as a consequence important changes in food webs.