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Experiments by Invited Researchers

 

Role of genotypic and phenotypic (allelopathy) diversity of harmful algal blooms (HABs): case of the dinoflagellate Alexandrium tamarense

Project acronym: HyIII-NTNU-20
Name of Group Leader: CATHERINE LEGRAND
User-Project Title: Role of genotypic and phenotypic (allelopathy) diversity of harmful algal blooms (HABs): case of the dinoflagellate Alexandrium tamarense
Facility: Total Environment Simulator
Proceedings TA Project: Role of genotypic and phenotypic (allelopathy) diversity of harmful algal blooms (habs): case of the dinoflagellate alexandrium tamarense
Data Management Report: Report

User-Project Objectives

The overall objective of this experiment is to test the ecological significance of genetic and phenotypic (allelopathy) diversity in the regulation of Alexandrium population dynamics in mesocosms.

Measurable scientific objectives of this project

  1. Investigate the changes of the gene expression profiles of Alexandrium over the bloom formation in order to understand the regulation of toxicity and growth
  2. Test the potential impact of different allelophatic genotypes on the success and genetic structure of an Alexandrium bloom
  3. Quantify the role of allelopathy on pelagic microplankton (eukaryotes and prokaryotes) communities during the development of an artificially induced bloom of A. tamarense in presence and absence of allelochemicals
    1. Test the effect of allelochemicals on phenotypic and phylogenetic changes in bacterial communities and their interactions with nanoflagellate grazers during a bloom of A. tamarense
    2. Test the direct and indirect effects on allelochemicals on protistan species (grazers and competitors) and communities.
  4. Provide a platform for further studies on allelopathy in aquatic systems and its implication in ecological processes

Short description of the work carried out

Achievements

  • Mesocosms (15) were run in Hopavågen 4-26 July 2009.
  • Alexandrium (inoculated) grew for 2 weeks, but never formed a bloom.
  • Emiliania huxleiyi outcompeted other phytoplankton during week 2 and bloomed in the mesocosms.
  • Sampling (multi variable) was performed during the study period.
  • Access to HYDRALAB staff was easy and efficient.
  • Access to dry-ice, liquid nitrogen, chemicals, consumables, freezer was very good.

Difficulties

  • Power supply (for the gene sequencer) was deficient towards the end of the study.
  • Alexandrium cultures (started at NTNU-BIO-PMS) in May 2009 were not in a good shape prior to the experiment. Backup cultures were flown from Germany and were not 100% healthy at the start of the experiments.

Highlights of important research results

  • Gene expression profiles of Alexandrium during growth in mesocosms (microarrays and pyrosequencing).
  • Data on the prevalence of different genotypes of Alexandrium in mixed communities (AFLP and microsatellites in combination with qPCR and single cell PCR)
  • PSP toxin profiles in different trophic levels (meta-, micro-zooplankton, phytoplankton)
  • Protistan grazing on Alexandrium spp. (tracer, epifluorescence)
  • Impact of lytic Alexandrium on nanoflagellate bacterivory (fluorochrome, epifluorescence)
  • Large dataset on marine eukaryotic diversity (plankton size) (microscopy + molecular methods)
  • Large dataset on prokaryotic diversity (bacteria) (DGGE, sequencing)
  • New bacterial isolates from Hopavågen lagoon (sequencing, cultures)

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