Interactions of herbivores and planktonic algae are essential for the marine food chain. In the recent years field experiments have shown that even unicellular algae can defend themselves. In our paper we can directly track down the reasons of this chemical defense in laboratory experiments.

The paper combines ecological and chemical methods to prove a new concept in plankton ecology. Doing this we identified two strains of one algal species—one defended, one not defended—that can be used as a perfect tool for further lab and mesocosm experiments.

This paper describes how microscopically small algae can defend against grazers by chemical means. This is a remarkable strategy because it can function even in the very dilute environment of the plankton (plankton = the community of all free-floating organisms in the sea).

I am a chemist working on the chemical ecology of marine algae and met Serge Poulet, the ecologist who was working with us on the project during a field trip. There we decided to combine chemical and biological approaches to find out more about the interactions in the plankton.