Research team

Ecosystem Management

Expertise

Diatoms, unicellular autrotrophic algae, are on of the most abundant and diverse algal groups in the worlds. As primary producers, they are at the base of all food chains and as such of prime importance in the functioning of the aquatic ecosystems. Each of the (estimated 50.000) species has its own preferences for a broad variety of environmental parameters such as pH, conductivity, nutrients, heavy metals and organic pollutants. Changes in their (physico-chemical) environment automatically lead to changes in the composition of the diatom communities in rivers, lakes and soils. Since a few years, the European Union obliges its member states to guarantee the good quality of its waterbodies, both standing and running. This so-called European Water Framework Directive requires the constant monitoring of the water quality of lakes and rivers in the entire European Union. One of the principal indicators of changes in water quality are freshwater diatoms. The past 20 years, several systems have been developed to use and transform records of the diatom communities as bio-indicator. The use of diatoms has several advantages: (1) they react very fast to changes in their environment, (2) they are always very abundantly present in waterbodies, (3) their sampling and sample preparation is rather simple and low-cost and (4) the diatom analysis can be very easily be transformed into water quality indices. One of the major disadvantages however is the expertise that is necessary to analyse the diatom community. Not only are there a large number of species (approx. 1500 in Belgium alone), their identification requires the use of a performing light microscope and sometimes even a scanning electron microscope, and a constant training to get familiar with the latest taxonomic updates as new species are constantly described and ecologically better characterized. The proposed research expertise includes professional sampling on site, preparation of the diatom samples and analysis and counting of the diatom slides using a light microscope. Once the diatom counts are available, the software package OMNIDIA allows a fast calculation of the diatom indices. All analyses and techniques are conform the European guidelines EN13946 (diatom preparation) and EN 14407 (diatom counting).

Global species structure, colonization-extinction dynamics and adaptive radiation of the cosmopolitan diatom clade Pinnularia borealis. 01/10/2016 - 30/09/2018

Abstract

Diatoms, unicellular algae with a siliceous cell wall, are ecologically widespread and highly diverse organisms. Until recently, it was believed that most diatom species are worldwide distributed. However, increasing evidence suggests the opposite to be true for many species. Phylogenetic data revealed that our model species Pinnularia borealis consists of morphologically similar forms, which in fact correspond to different species. With this project we aim to test a series of hypotheses based on an in depth study of this species complex. First, we will develop and characterize a culture collection of Pinnularia borealis strains from various regions using a combination of morphology, genetics and ecophysiology. This will allow us to assess to which extend ecophysiological specialization is correlated with species formation and their global distribution during the evolution of the complex since its inferred origin 30-47 mil. years ago. In addition, the project will use targeted sequencing of environmental samples and phylogeographic analysis to document patterns of local and regional diversity of this complex in ice-free regions in Antarctica and the Arctic representing a range of lake provinces differing in age and degree of geographical isolation. This will allow us to test the relative roles of dispersal constraints and local adaptation for understanding species distributions.

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Global species structure, colonization-extinction dynamics and adaptive radiation of the cosmopolitan diatom clade Pinnularia borealis. 01/10/2014 - 30/09/2016

Abstract

Diatoms, unicellular algae with a siliceous cell wall, are ecologically widespread and highly diverse organisms. Until recently, it was believed that most diatom species are worldwide distributed. However, increasing evidence suggests the opposite to be true for many species. Phylogenetic data revealed that our model species Pinnularia borealis consists of morphologically similar forms, which in fact correspond to different species. With this project we aim to test a series of hypotheses based on an in depth study of this species complex. First, we will develop and characterize a culture collection of Pinnularia borealis strains from various regions using a combination of morphology, genetics and ecophysiology. This will allow us to assess to which extend ecophysiological specialization is correlated with species formation and their global distribution during the evolution of the complex since its inferred origin 30-47 mil. years ago. In addition, the project will use targeted sequencing of environmental samples and phylogeographic analysis to document patterns of local and regional diversity of this complex in ice-free regions in Antarctica and the Arctic representing a range of lake provinces differing in age and degree of geographical isolation. This will allow us to test the relative roles of dispersal constraints and local adaptation for understanding species distributions.

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Communications and popularization platform of the Belgian Polar research. 15/12/2003 - 31/12/2006

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Belgian Polar research cluster. (BE-POLES) 15/12/2003 - 31/12/2006

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Study of the current, subfossil and future bio-diversity in the subantarctic region: the role of dispersal, colonization and resistance to climatic warming. 01/10/2003 - 31/12/2005

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01/10/2002 - 30/09/2005

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Changes in biodiversity related to Global Change in subarctic communities. 01/02/2002 - 31/12/2005

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01/07/2001 - 31/12/2001

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    Biogeography of Subantarctic epifytic diatom communities from existing bryophyte collections. 01/01/2000 - 31/12/2001

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    The biogeographical zonation of the Subantarctic region will be investigated, based on the presence of epifytic moss diatoms. The diatom communities that will be used in this survey, will be taken from moss collections, made on the different islands of this region. A similarity-analysis of the results should clarify whether the existing biogeographical zonations of the Subantarctic region (based on higher plants vertebrates) can also be adopted to protists, i.c. diatoms.

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      01/10/1999 - 30/09/2002

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        01/10/1997 - 30/09/1999

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          01/10/1995 - 30/09/1997

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