Gestafyrirlestur 5. mars. Sara Harðardóttir þörungafræðingur flytur erindi

Sara Harðardóttir

Fimmtudaginn 5. mars mun Sara Harðardóttir, þörungarfræðingur og nýdoktor við jarðfræðistofnunina GEUS í Kaupmannahöfn og Laval University í Kanada, halda erindið: Marine Battlefields: Toxic Diatoms and their Copepod Grazers.

Erindið verður flutt í fyrirlestrarsal á jarðhæð á Skúlagötu 4, kl 12:30 og er öllum opið. Erindið verður á ensku.

Phytoplankton live by nutrient uptake and photosynthesis and they wander with the ocean currents. As pleasant as that may sound, the pelagic is a place of combat. Predation is a major cause of mortality in phytoplankton and their success and survival depends on defense strategies just as much as utilization of nutrients and sunlight. Defense strategies play a central role in the evolution and diversification of species and phytoplankton have evolved various methods to avoid predation, such as toxin production.

Certain species of the diatom genera Pseudo-nitzschia produce the toxin domoic acid as a response to specific environmental triggers. Domoic acid is known to cause harm to marine organisms such as seals, whales and sea birds as well as humans. The toxin can be vectored into the marine food web e.g. via copepods of the genus Calanus, that seemingly are not affected by this toxin. Recently, Sara and her colleagues demonstrated that two species of Pseudo-nitzschia induce toxin production in the presence of copepods, more specifically the response is found to be to predator cues, copepod amides, excreted from the copepods. Indicating domoic acid to be an inducible chemical defense against predation. However, the cells with induced toxin content are, nevertheless, grazed upon. The toxin production does not deter grazing but enhances acid uptake by the grazers. This enigma and the result of the following studies were grazer specific responses, cost of toxin production, the effect on copepods and metabolic pathways of toxin production were investigated by the use of classical experimental approaches and state of the art molecular techniques will be the topic of Sara’s talk. As well as domoic acid production in strains of the species Pseudo-nitzschia seriata in Hvammsvík, Iceland.

A popular science article on this work is available in Danish https://aktuelnaturvidenskab.dk/giftige_kiselalger