Symbiont-driven disorders in zooplankton reproduction (iCard)

Alterations in zooplankton communities are occurring on a global scale, but we still have a limited understanding of their drivers.

Despite the widely observed linkage between decreased population abundances and sex ratio shift toward females, its biological basis and the implications for the community structure are poorly understood.

In several Baltic copepod species, we have discovered a pathogen-like endosymbiotic bacterium Cardinium that has been reported to cause various reproductive disorders in other arthropods. We hypothesize that Cardinium manipulates reproduction by decreasing the production of males.

We also hypothesize that environmental factors can affect the infestation rate resulting in changes in the sex ratio and recruitment in zooplankton.

Using experiments and long-term monitoring data, we will test these hypotheses by examining how the infestation affects reproduction success and host population dynamics in the Baltic Sea zooplankton under various environmental conditions.

The project outcome will be incorporated into current regulatory efforts on pelagic indicator development via a dialogue with relevant HELCOM regional expert groups and stakeholders working with the implementation of the Marine Strategy Framework Directive.