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SUMMARY:Periphyton as bioindicator and community model
DTSTART:20131210T161500
DTEND:20131210T171500
DTSTAMP:20260609T084012Z
UID:21b6223f143ca30f793ed2fc390797703e2832e604698890d1570570
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Alexandra Kroll\, Environmental Toxicology\, EAWAG\, Dueben
 dorf (CH)\nAbstract:\nNatural biofilms also known as periphyton colonize s
 ubmerged surfaces in freshwater and marine ecosystems. They are taxonomica
 lly diverse and dynamic communities of bacteria\, algae\, and fungi that p
 rovide essential ecosystem services such as primary production\, nutrient 
 cycling and filtration of particles and pollutants.Periphyton adapts quick
 ly to environmental conditions among others by changes in species composit
 ion.The sensitivity of periphyton to environmental conditions including an
 thropogenic stressors makes it an important bioindicator. However\, the co
 mplexity and dynamics of these microbial communities poses a challenge to 
 identifying appropriate descriptors\, a useful level of detail and linking
  observed changes to understand underlying mechanisms.\nAgainst this backg
 round we aim at establishing a tiered assessment of periphyton status usin
 g flow cytometry as first-tier followed by more detailed analysis of diver
 sity and structure.\nWe are currently establishing the assessment of funct
 ional groups (by Flow cytometry)\, molecular diversity (community fingerpr
 inting by ARISA)\, 3D structure (by Confocal laser scanning microscopy)\, 
 and extracellular chemistry (by quantification of organic carbon and nitro
 gen compounds). An indoor colonization setup is used for long-term culturi
 ng of periphyton and exposure to chemicals. Flow cytometry and correspondi
 ng data analysis will be adapted to the characteristics of periphyton to a
 nalyze changes of functional groups (i.e. organism size\, growth form\, pi
 gmentation) representing biological characteristics that are connected to 
 ecosystem functions. This data will be linked with information on the mole
 cular diversity and taxonomic species composition as well as structure and
  extracellular chemistry. Integrative endpoints such as biomass and photos
 ynthetic activity are used to complement this information.\nThe talk will 
 summarize the current state of the tiered assessment scheme and present fi
 rst results on the impact of selected pesticides and nanoparticles on peri
 phyton detected by this scheme.Dr Alexandra Kroll's research activities ai
 m at (1) understanding the dynamics of phototrophic organisms in periphyto
 n (*) when exposed to low levels of new anthropogenic contaminants against
  the background of existing pollution and natural variations\, (2) at prov
 iding efficient combinations of analysis tools for periphyton integrity on
  the structural and functional level\, (3) and also to provide data sets t
 hat are useful to model changes in periphyton with regard to anthropogenic
  stressors.\n(*) periphyton is an indispensible part of freshwater ecosyst
 ems which is a widely used indicator for water quality\, and an important 
 receptor for contaminants\, which enhances accumulation of pollutants in t
 he food chain. 
LOCATION:GR A3 31 http://plan.epfl.ch/?room=GR%20A3%2031
STATUS:CONFIRMED
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