Acartia tonsa. Foto: Erik Selander.

PhD defense about copepods and toxic algea

Wednesday 31 Jan 18

Time & Place

Friday, 2 February 2018, 1:00 p.m.

Building 303A, auditorium 41
2800 Kgs. Lyngby

The thesis

A copy of the thesis "Prey selection and behavior of copepods fed on toxic and nontoxic algae" is available for reading at DTU Aqua. Please, contact Rikke Hansen,

Do copepods feed on toxic algea, or do they have strategies to avoid them? This is the subject of Jiayi Xu’s PhD thesis which she will defend on 2 February 2018.

Copepods and other types of zooplankton play a vital role in marine ecosystems by linking phytoplankton production to higher trophic levels. Some phytoplankton species are able to produce toxic substances which may affect both fish and humans consuming seafood. As toxic algal blooms appear to increase worldwide, it is relevant to find out whether copepods feed selectively on toxic algae.

PhD Student Jiayi Xu, Centre for Ocean Life at DTU Aqua, has investigated the feeding response of individual copepods to algae of various toxicity using high-speed video microscopy. She observed five distinctly different behavioral responses of copepods to the toxic prey, ranging from no effects to deterrent effects and toxic effects. In scanning about 15 different strains of toxic algae she observed, however, that the most common response was that the copepods capture, ‘taste’, and then reject toxic algae that remain undamaged. This is a novel discovery and solves a long-standing issue in phytoplankton ecology. 

About the defence

On Friday 2 February 2018, Jiayi Xu will defend her PhD thesis "Prey selection and behavior of copepods fed on toxic and nontoxic algae" at DTU’s campus in Lyngby. The defence takes place at 1 p.m. in building 303A, auditorium 41.


  • Principal supervisor: Professor Thomas Kiørboe, DTU Aqua
  • Co supervisor: Professor Per Juel Hansen, Department of Biology, University of Copenhagen


  • Senior Researcher Sigrun Jonasdottir, DTU Aqua
  • Associate Professor Erik Selander, University of Gothenburg, Sweden
  • Senior researcher Enric Saiz, CSIC, Spain

Chairperson at defence

  • Senior Researcher Josianne Gatt Støttrup, DTU Aqua
17 JANUARY 2019