DynaCom (Sp 4)
In our project we investigate resource driven microalgae - consumer interactions in a spatial setting in a metacommunity context, combining field observations with experimental manipulations. Benthic microalgae (microphytobenthos, MPB) are important primary producers in shallow coastal marine sediments. MPB comprises a high variance in traits regarding mobility, resource acquisition and grazing tolerance. Thereby, MPB distribution, biomass and composition reflect variable patterns of nutrients, light availability, grazing and hydrodynamically forced dispersal. Despite high MPB functional diversity and patchy distribution, spatially coupled consumer-resource interactions or biodiversity-functioning relationships have rarely been explored in this system so far.
In the first phase of SP4, we will investigate temporal and spatial dynamics of MPB biomass and composition through different seasons on the experimental islands south of Spiekeroog, as well as on transects ranging from the pioneer zone of the salt marsh towards the open Wadden Sea at the islands of Spiekeroog, Wangerooge and Norderney. These sites differ in hydrographic conditions that determine algal dispersal and resource availability. In collaboration with SP5, field-sampling campaigns will allow us to relate MPB dynamics to hydrodynamics, nutrient regimes and herbivores at different spatial and temporal scales. From field samples, algal species comprising different cell sizes, mobility and resource demand traits will be isolated for experimental manipulations, also conducted in collaboration with SP5. Small-scale laboratory experiments will assess consumer- and prey-specific traits determining trophic interactions (mobility, resource demand and acquisition, growth and grazing rates). Mesoscale mesocosm experiments will then serve to explicitly manipulate the spatial patterning of resources in an experimental landscape and determine resulting consumer-prey interactions. Patterns observed in the experiments will be compared and related to patterns observed in the field to enhance our understanding of bottom-up and top-down control of MPB in a spatial context.