WP3 Climate perspectives

Eelgrass restoration in a climate perspective.

The continuously increasing atmospheric CO2 and the resulting global warming are expected to
have implications for the future eelgrass performance and restoration efforts. While eelgrass
may gain competitive advantage over macroalgae with increasing CO2 availability, warming
could have considerable negative impacts on eelgrass recolonization due to temperature stress
on plant physiology and oxygen balance (Winters et al. 2011; Raun & Borum submitted).

Eelgrass responses to changing CO2 and temperature will be examined experimentally to
provide climate change input data for modeling scenarios in WP 4 of the long-term fate of the
recovery actions developed and applied in WP 1, WP 2 and WP 5. The increase in atmospheric
CO2 can potentially have a positive effect on eelgrass photosynthesis (Duarte et al. 2008). The
impact of atmospheric CO2 stimulation will be examined in laboratory experiments with and
without possible counteracting effects of the high inorganic carbon availability in sediment and
near-bottom water. In contrast, warming, and not the least the expected increase in extreme
periods of high temperatures, is expected to have major implications for eelgrass performance
and survival in shallow waters (Moore & Jarvis 2008); particularly in combination with organic
loading and associated toxic levels of sulfide (van der Heide et al. 2012). The responses of
seedlings and mature shoots to high temperatures and oxygen stress will be examined using
microelectrodes and advanced techniques developed for analyses of stress on human tissues.

The ecological relevance of these experimental results will be evaluated in relation to the
predicted future climate change. Apart from providing a better understanding of eelgrass
physiological responses, this WP will provide refined input data to the ecological 3D-model
developed in WP 4 for identifying suitable areas for eelgrass restoration efforts by WP 2 and
WP 5 and improve forecasting of future eelgrass cover in selected coastal areas.