Lac Hertel

Fussmann Lab
Department of Biology

Lab Members - Postdoctoral Fellows

Romana Limberger

Romana Limberger

Postdoctoral Fellow
Funded through an Erwin Schrödinger Fellowship of the Austrian Science Fund, FWF
Current position: Postdoctoral Fellow at EAWAG, Switzerland
Ph.D. (2011): University of Salzburg, Austria
M.Sc. (2003): University of Vienna, Austria

Postdoctoral Research

While physiological and ecological responses to global environmental change have been the focus of numerous studies, research on evolutionary responses is lagging far behind. In particular, there is a lack of studies on potential feedbacks between ecological and evolutionary processes in changing environments. Species-specific differences in evolutionary rates could change community dynamics, while ecological processes such as species interactions and dispersal likely affect a species' adaptive potential.

Using algae as model organisms, I am analysing
  1. whether species-specific differences in the rate of adaptation affect community dynamics
  2. whether the presence of interspecific competition influences adaptation to gradual environmental change
  3. whether the effect of environmental change on biodiversity depends on habitat connectivity.

These research questions will be analysed with a combination of microcosm and mesocosm experiments, as well as a modeling approach.

Mehdi Cherif

Mehdi Cherif

Postdoctoral Fellow
Current position: Assistant Professor, University of Umeå, Sweden

Brief Bio of Mehdi Cherif
  • Postdoctoral Fellow (2009-2012): Dept. Biology, McGill University (advisor: Prof. G. Fussmann )
  • Postdoctoral Fellow (2007-2009): Dept. Biology, McGill University (advisor: Prof. M. Loreau )
  • Ph.D. (2007): Pierre et Marie Curie University, Paris, France
  • M.Sc. (2003): Claude Bernard University, Lyon, France
  • B.Sc. (2001): Ecole Normale Supérieure, Paris, France
Postdoctoral Research [French version]

My global interest is in linking food webs and ecosystem functioning:

  • How do food web structure and dynamics affect matter and energy flows in ecosystems?
  • In return, how are food web properties constrained by the ecosystem flows?

During my PhD, I approached these questions through ecological stoichiometry. I looked at the effects of the elemental chemical composition of plants, herbivores and decomposers on their trophic interactions (Cherif, Cotner, & Loreau, in prep.; Cherif & Loreau, 2007, 2009, in prep., submitted; Doi, et al., in press).

During my first postdoctoral position in Prof. Loreau’s lab, I concentrated on how allometric constraints on individual properties of the organisms (rates of metabolism, reproduction, capture, ingestion, ...) affect the structure of evolving food webs. Effects of physical factors were included to simulate the contrasting environments of terrestrial and aquatic habitats. The goal was to test the hypothesis that the differences between aquatic and terrestrial food webs came from physical factors, such as gravity, light absorption, and density, acting on organisms through their body size.

In my current postdoctoral position, I put my modeling skills to service in an NSERC-SPG project (to Fussmann, Archambault, Lovejoy, Tremblay) whose title is "Integrating across scales in marine aquaculture: the role of trophic dynamics and nutrient recycling for mussel production". I intend to contribute with models that are meant to:

  1. understand the effects of intraguild predation (zooplankton consumption by mussels) on mussel growth and on plankton dynamics;
  2. understand the effects of detritus production by mussels on plankton and how it feedbacks on mussels;
  3. describe the whole ecosystem surrounding mussels cultured at the site where field experiments for the project are taking place (Havre-Aux-Maisons lagoon on Magdalen Islands).

Recherches Postdoctorales [English version]

Mon objectif général de recherche est de caractériser le lien entre fonctionnement des écosystèmes et réseaux trophiques:

  • Comment la structure et la dynamique des réseaux trophiques affecte-t-elle les flux de matière et d’énergie dans les écosystèmes?
  • Comment les propriétés des réseaux trophiques sont-elles contraintes en retour par les flux dans les écosystèmes?

Au cours de mon doctorat, j’ai abordé ces questions à travers l’approche de la stœchiométrie écologique. J’ai étudié les effets de la composition chimique élémentaire des plantes, des herbivores et des décomposeurs sur leurs interactions trophiques (Cherif, Cotner, & Loreau, en préparation; Cherif & Loreau, 2007, 2009, en préparation, soumis; Doi, et al., sous press).

Au cours de mon premier poste postdoctoral dans le laboratoire du professeur Loreau, je me suis intéressé aux façons dont les contraintes allométriques sur les propriétés des individus (taux métaboliques, reproductifs, de capture, d’ingestion, ...) pouvaient affecter la structure de réseaux trophiques en évolution. J’ai inclus les effets de facteurs physiques afin de simuler les contrastes existant entre les environnements des habitats terrestres et aquatiques. L’objectif était de tester l’hypothèse que les différences entre réseaux trophiques aquatiques et terrestres viennent de facteurs physiques tel que gravité, absorption de la lumière et densité du milieu, agissant sur les organismes à travers leur taille corporelle.

Pour mon poste postdoctoral actuel, je met mes connaissances en modélisation au service d’un projet financé par une bourse CRSNG-SPS(à Fussmann, Archambault, Lovejoy, Tremblay) intitulé "Intégration sur plusieurs échelle en aquaculture marine: le rôle des dynamiques trophiques et du recyclage des nutriments dans la production des moules". Je compte contribuer à travers des modèles ayant pour objectifs:

  1. de comprendre l’effet de la prédation intraguilde du zooplancton par les moules sur la croissance des moules et la dynamique du plancton;
  2. de comprendre l’effet des la production de détritus par les moules sur le plancton et l’effet en retour sur les moules elles-mêmes;
  3. de décrire l’écosystème entourant les moules cultivées sur le terrain où des expériences ont lieu dans le cadre du projet (lagon de Havre-Aux-Maisons aux Îles de la Madeleine).

Alison Derry

Alison Derry

NSERC Postdoctoral Fellow
Current position: Associate professor, Université du Québec à Montréal

Brief Bio of Alison Derry
  • NSERC Postdoctoral Fellow (2008-2010): Dept. Biology, McGill University
  • Ph.D. (2007): Dept. Biology, Queen’s University
  • M.Sc. (2001): Dept. Biological Sciences, University of Alberta
  • B.Sc. (1997): University of Guelph

Postdoctoral Research

Predator-prey interactions in metacommunities have potential to indirectly influence the outcome of competitive interactions between prey species in degraded habitats by altering the flow of prey migration among habitat patches (Orrock et al. 2008). Although this idea could theoretically be important for understanding stress and recovery responses of communities at disturbed sites, it has not been experimentally tested. One example of an environmental stressor that is expected to increase in frequency among lakes across the landscape is toxic cyanobacteria. Harmful algal blooms comprised of cyanobacteria pose an increased threat because of rising temperatures associated with climate change and over-enrichment of freshwater habitats from human activities (Jöhnk et al. 2008; Paerl & Huisman 2008). Toxic cyanobacterial blooms can cause species compositional changes in aquatic communities, are often stripped of top predators (e.g., fish), and could potentially act as sink environments for intolerant species dispersing among lakes in metacommunities.

I plan to set up an experimental metacommunity with rotifers and algae in microcosms to test the following:

Are habitats impacted by toxic cyanobacteria (Microcystis aeroginosa) subject to source-sink dynamics in prey species depending on the strength of predation in source habitats?

  • Is there selective predation by predator Asplanchna brightwelli on prey (Brachionus rotifers) in a source environment (no toxic algae)?
  • What is the outcome of competitive interactions between prey species (Brachionus calyciflorus and Brachionus havanensis) in source (no toxic algae) and sink (toxic algae) environments?
  • Does species-selective predation in a source environment indirectly alter competitive interactions between prey species in a sink environment containing toxic algae?

Selected References:

Orrock et al. 2008. Ecology 89: 2426-2435.
Jöhnk et al. 2008. Global Change Biology 14 : 495-512.
Paerl & Huisman 2008. Science 320: 57-58.