How do copepods respond to toxic prey? And can the copepods acclimate to algal toxins?

Wednesday 17 Jan 18


Thomas Kiørboe
DTU Aqua
+45 35 88 34 01


Lasse Tor Nielsen
DTU Aqua
+45 35 88 34 11


Jiayi Xu
Many species of phytoplankton produce substances that are toxic to both human consumers and planktonic grazers, and toxin production is often considered a defense mechanism. But can grazers de-select the toxic prey cells? And can they acclimate to the toxins?

These have been a long-standing issues and critical for understanding the functional role and evolution of toxicity in phytoplankton, and the implications of toxicity to the formation of blooms of toxic algae. To get insight into the mechanisms we used direct video observations of the behavioral response to toxic algae (different strains of Alexandrium tamarense). We examined two copepod species with different foraging modes, and we followed their behavior during 5 days. Both copepod species consumed the toxic algae at a reduced rate but the mechanisms differed: one species was intoxicated, while the other species managed to deselect the algae. The latter is a true grazer deterrent response that yields the toxin producing algae a competitive advantage. We found limited acclimation to algal toxins but mortality rates were low and the various responses thus all allow the copepods to survive harmful algal bloom. However, only grazer deterrent effects of toxins can promote the development of blooms of toxic algae.

Read the paper here

Jiayi Xu, Lasse Tor Nielsen, Thomas Kiørboe. Foraging response and acclimation of ambush feeding and feeding-current feeding copepods to toxic dinoflagellates. Limnology and Oceanography, 2018, DOI: 10.1002/lno.10782.
19 FEBRUARY 2018