Exploring functional interfaces: extreme biogenic fluctuations may amplify or buffer environmental stress on organisms associated with marine macrophytes

• Applicant: Professor Christian Pansch-Hattich, Ph.D., since 10/2016
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 302250798

The overarching aim of the project is to refine our understanding of coastal ecosystem responses to predicted Global Change scenarios by evaluating the capacity of stress-modulation by strong biogenic fluctuations of the environment at an organism-relevant scale. Coastal communities are often exposed to strong environmental fluctuations due to seasonal or diurnal events (e.g. water mixing, tides, primary production). The intensity of such fluctuations tends to increase with decreasing spatial scale and is extremely high in the sub-mm diffusive boundary layer (DBL) covering macrophyte surfaces. These fluctuations, in, for example, temperature, pH, CO2 and O2, are often of much greater magnitude than predicted changes in the course of Global Change. They may either offer temporal refuges from environmental stress or they may harden organisms to environmental changes. The mechanism of coastal benthic organisms to cope with such environmental fluctuations is virtually unstudied. Epibionts inhabiting the DBL including calcifying bryozoans, tube worms and coralline algae experience strong but temporally instable gradients in and extremes of O2, CO2 and H+ (pH) concentrations depending on the macrophytes metabolic activity (photosynthesis and respiration rates) and ambient conditions (pilot study). These biogenic fluctuations have the potential to mask, amplify or buffer environmental stress including Global Change pressures. Considering the importance of macrophytes (e.g. seagrass, kelp, bladder wreck) as bioengineers of diverse and productive coastal ecosystems and the diverse and ecologically important epibionts they support, it is of primordial importance to investigate their interaction under Global Change. Therefore, the specific aims of this project are (i) to characterize the dynamics of the DBL of macrophytes under different Global Change scenarios (warming, ocean acidification, hypoxia), (ii) to investigate its effect on calcifying epibionts and their ability to acclimatize or adapt to a strongly fluctuating regime, (iii) to identify potential pre-adaptation of epibionts to different micro-habitats (macrophyte vs. inert surface DBL) and (iv) to assess the potential of macrophytes to provide temporal refuge from ocean acidification and hypoxia. Results are expected to shed light on mechanisms of organisms to cope with fluctuations and their tolerance towards Global Change, while latter may differ significantly from results based on traditional steady-state open-ocean Global Change experiments.

• DFG Programme: Research Grants
• International Connection: USA
• Co-Investigator: Joshua Mackie
• Cooperation Partner: Dr. Dirk de Beer
• Ehemalige Antragstellerin: Dr. Yvonne Sawall, until 9/2016