Work package POL 5: Autecology of planktonic key species and groups
Ocean biogeochemistry is increasingly coming under focus as a major regulator of
atmospheric CO2 concentrations. Biogeochemical cycles are driven by trophic interactions
within pelagic food webs comprising an as yet unknown range of species. Categorising
organisms into functional groups is a convenient way of rendering this biological diversity
and hence complexity amenable to modelling. However, a mechanistic understanding of the
factors regulating the wax and wane of the organisms comprising functional groups is a
prerequisite to improving the predictive power of models. These factors range from physicochemical
characteristics of the environment (bottom-up factors) to interactions with other
organisms (pathogens and grazers = top-down factors). Each species represents a set of
adaptive traits that have been selected in the course of evolution by a given range of these
factors. The relevant properties of these species can be determined by means of a variety
of approaches that range from detailed, interdisciplinary field observations, in-situ
perturbation experiments, mesocosm to beaker experiments, assessments of physiological
and chemical properties and mapping of the genomic potential. Since relatively few genera
and species appear to play key roles in trophic interactions and biogeochemical fluxes we
will focus our efforts on understanding the autecology of selected species. This knowledge
will help link biogeochemical cycles with ecological processes that shape the structure and
functioning of pelagic systems. The ultimate goal is to advance the predictive power of earth
system models.