RESOURCE DISTRIBUTION AND CONSUMER MOBILITY DETERMINE MACROZOOBENTHOS – MICROALGAE INTERACTIONS IN TIDAL FLATS

Benthic microalgae (microphytobenthos, MPB) are important primary producers in shallow coastal marine sediments and comprise a high taxonomic and functional diversity regarding mobility, resource acquisition and grazing tolerance. MPB distribution, biomass and composition thus 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 have rarely been explored in this system so far. Conducting a benthic mesocosm experiment, the current study investigated the interactive effects of spatial nutrient distribution and grazing by macrozoobenthic consumers of differing mobility on the biomass, diversity and composition of a multispecies MPB community. Before grazer addition, nutrient supply mode didn’t affect MPB biomass, but altered MPB diversity and composition, leading to increased MPB diversity under heterogeneous nutrient supply. Grazing effects depended on consumer mobility and nutrient distribution. Mobile consumers exerted a significantly higher grazing pressure on MPB biomass compared to sedentary consumers, and this effect was stronger under homogenous nutrient supply. MPB diversity was significantly higher with mobile consumers and under homogenous nutrient supply. This study enhances our comprehensive understanding of resource-driven consumer-microalgae interactions in tidal flat communities and emphasizes the relevance of incorporating a spatial context when studying this highly variable ecosystem.

Presentation Preference: Oral

Primary Presenter: Stefanie Moorthi, Carl-von-Ossietzky Universität Oldenburg (moorthi@icbm.de)

Authors:

Stefanie Moorthi, Carl-von-Ossietzky Universität Oldenburg, Germany  (moorthi@icbm.de)

Joanne Yong, Carl-von-Ossietzky Universität Oldenburg, Germany  (joanne.yong.ya.lin@uni-oldenburg.de)

Jana Dewenter, Carl-von-Ossietzky Universität Oldenburg, Germany  (jana.dewenter@uni-oldenburg.de)

Sven Rohde, Carl-von-Ossietzky Universität Oldenburg, Germany  (sven.rohde@uni-oldenburg.de)

Helmut Hillebrand, Carl-von-Ossietzky Universität Oldenburg, Germany  (helmut.hillebrand@uni-oldenburg.de)