I'm currently involved in the  following projects 

Linking resource competition and 

biodiversity in meta-ecosystems

Resource competition is one of the most fundamental species interactions in ecology. It has been studied intensely in the last decade as a major driver for the structure and species richness of biological communities. Recently, it is increasingly acknowledged that spatially structured communities are not only connected by dispersal of organisms but also by flows of matter and resources. However, despite the fact that such meta-ecosystems are an emerging topic in community ecology, not much is known about competition in spatially structured environments where species may modify resource distributions. In the proposed research project we aim to gain a mechanistic understanding about the relationship between resource competition, biodiversity and ecosystem functioning in meta-ecosystems. To address this question we will develop a framework for describing resource competition in meta-ecosystems. We will model a meta-ecosystem as a system of diffusively connected patches that differ in the levels and ratios of resources. This approach enables us to study the effects of spatial resource distributions on the eco-system functioning. In particular, we will (i) determine species traits that enhance competitive abilities in a spatially structured environment, (ii) quantify how a single species shapes its spatial resource environment, (iii) investigate two-species and multi-species competition in a meta-ecosystem, as well as conditions that maximize biodiversity, (iv) analyse feedbacks between resource and biomass distributions, and their influence on the resource-use, productivity and biodiversity, and (v) explore the relationship between resource-use, primary production and biodiversity patterns in patchy meta-ecosystems. Finally, we have the unique opportunity to validate our theoretical predictions against experiments with plankton communities in a chemostat-like system consisting of serially connected vessels where two essential nutrients are supplied from opposing ends of the system  (so-called gradostat).

Our approach will enable to assess the diversity and productivity both at the system and the patch level and admits theoretical investigations, yielding a novel, high-resolution analysis of meta-ecosystem processes. The results of this research project will help to bridge the gap between classic competition theory and spatially structured meta-ecosystems and will be of general relevance for enhancing our understanding of species coexistence and biodiversity-functioning relationships in field communities.

PI:                   Dr. Alexey Ryabov
Collaborators: Prof. Dr. Bernd Blasius,   Dr. Robert Ptacnik
Duration:         3 year
Funging:          DFG


Flexibility matters: Interplay between trait diversity and ecological dynamics using aquatic communities as model systems

Adaptive trait dynamics of lake phytoplankton at short time scales

  Our proposed project is designed to improve our understanding of the short-term changes of trait diversity in ecological communities in response to the ambient environment and its influence on ecosystem functioning.  For this we will use phytoplankton communities in freshwater lakes as a model system.  Recent advances in monitoring techniques by flow cytometry allow to simultaneous access a multitude of phytoplankton traits at an unprecedented temporal resolution.
 Using these methods we will monitor the trait diversity of phytoplankton communities at Lake Greifensee  (Switzerland) at short time scales and at different depth and different seasons.  Based on the obtained data we will extract quantitative characteristics of the trait-composition and -diversity, which will allow us to track the ecological dynamics and the adaptive response (flexibility) of lake phytoplankton to ambient conditions.  Using this framework we will test the hypothesis that dynamic trait diversity is a key concept that links the environment to ecosystem functions through mechanisms such as ecological dynamics and adaptive flexibility.  Our data-analysis will be complemented by mathematical modeling which provides a mechanistic underpinning of the interaction of external disturbances, the resulting ecological dynamics and adaptive changes in traitdiversity, and the emerging ecosystem functions.  The proposed research includes (i) highresolution sampling of trait-spectra in lake phytoplankton, (ii) quantification of trait diversity, (iii) analysis of the adaptive dynamics of trait diversity, (iv) the effect of trait diversity on ecosystem functioning, and (v) trait-based modeling of phytoplankton diversity.  The results of the project have potential impact for effective ecosystem management by providing insights into eco-evolutionary feedbacks between trait-diversity and the ecosystem-flexibility at short time scales.  The results will be valuable for predicting the functional consequences of biodiversity loss and environmental change caused by humans.

PI:                    Prof. Dr. Bernd Blasius
Collaborators: Dr. Francesco Pomati
Duration:         3 year
Funding:          DFG

Polar Time

During evolution, a wide range of organisms from cyanobacteria to humans have adapted to the day-night cycle, caused by the earth’s rotational movements, by developing an endogenous timing system – a circadian clock – that allows synchronization of metabolism, physiology and behaviour with the environment and that also may modulate seasonal responses. In marine organisms in general, little is known about the principles of endogenous clocks and how these clocks interact with environmental cycles. Marine ecosystems are currently experiencing rapid anthropogenic climatic changes. In particular, polar and sub-polar latitudes comprising the fastest warming regions on the planet with profound impacts on the marine environment. The overall aim of the Helmholtz Virtual Institute (HVI) PolarTime is to create a center of excellence of international standing to study the principles, interactions and evolution of endogenous biological rhythms and clocks in polar pelagic organisms. Emphasis will be placed on invertebrate key species who’s biology is so pervasive as to dictate ecosystem functioning. The Southern ocean key species Antarctic krill, Euphausia superba, will act as model organism to study the endogenous clock machinery and its effect on daily and seasonal life-cycle functions. The results will act as solid basis to study and understand the mechanisms of temporal synchronization of other key polar pelagic organisms. Embedded modelling studies will enable us to understand and predict how the ongoing environmental changes will impact the clock machinery and consequently the life cycle of key species and hence the whole polar marine ecosystem.

In this project I develop and analyse an ontogenetic model of krill development

Project PI:   Prof. Dr. Bettina Meyer
Duration:     5 year
Homepage:  http://www.polartime.org/


Competition for resources 

The principles of species coexistence have mostly been studied in uniform environments. However, natural environments are usually characterized by gradients and non-homogeneous distribution of resources. To date, we are largely unaware what conditions can provide maximum of the species richness and stability of the community, optimal stoichiometry and efficient use of resources.

The classical approach based on differential equation is a very convenient tool for the analysis of uniform systems. However, its straight forward application for competition in spatial systems encounters many mathematical difficulties. In order to investigate competition in spatially extended systems we have developed a graphical approach based on the analysis of invasion thresholds, - curves in space of species parameters which separate species that can survive in given conditions, from the species that cannot. Applying this analysis we have already discovered new fundamental results, which show a principle difference between competition in uniform and spatial system. See  publications for further information.

Currently we are developing this approach further. Motivated students are welcome to proceed this research.

Role of connectivity for maintenance of diversity in experimental plankton communities 

Aquatic diversity across temporal and special scales (AQUASCALE)

Duration: 01.12.2013 - 30.11.2016
PI:             Robert Ptacnik
Funding:  FWF

Other Projects