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Dinoflagellates of the genus Symbiodinium , the endosymbiont of reef corals, play an important role in coral-bleaching events which can be induced by prolonged enhanced seawater temperature anomalies, and which are predicted to occur at increasing frequencies and severities due to global warming. The genus Symbiodinium exhibits high genetic diversity with physiological variation within and among species, leading to a range of thermal tolerance. Although these variations have been examined in individual species, comprehensive comparative experimental data across several species are still rare. Therefore, in the present study, the photophysiological and thermal response patterns of six genetically characterized Symbiodinium genotypes were comparatively investigated. The six Symbiodinium genotypes were isolated from four different host species from the following biogeographic locations: Hawaii (Central Pacific), Panama (Caribbean), Florida (Caribbean), and Palau (West Pacific). Photosynthesis-irradiance curve and growth measurements at temperatures ranging from 20 to 33 °C were carried out. All physiological data clearly indicate significant differences in the response patterns of the six Symbiodinium genotypes. While some types photosynthesized, respired, and grew at 33 °C, others showed a partial or complete inhibition. The genotype-specific response over the experimental temperature reveals the potential range response of a given symbiont and variation between strains that adaptation might act upon.

Of all terrestrial ecosystems, peatlands store carbon most effectively in long-term scales of millennia. However, many peatlands have been drained for peat extraction or agricultural use. This converts peatlands from sinks to sources of carbon, causing approx. 5% of the anthropogenic greenhouse effect and additional negative effects on other ecosystem services. Rewetting peatlands can mitigate climate change and may be combined with management in the form of paludiculture. Rewetted peatlands, however, do not equal their pristine ancestors and their ecological functioning is not understood. This holds true especially for groundwater-fed fens. Their functioning results from manifold interactions and can only be understood following an integrative approach of many relevant fields of science, which we merge in the interdisciplinary project WETSCAPES. Here, we address interactions among water transport and chemistry, primary production, peat formation, matter transformation and transport, microbial community, and greenhouse gas exchange using state of the art methods. We record data on six study sites spread across three common fen types (Alder forest, percolation fen, and coastal fen), each in drained and rewetted states. First results revealed that indicators reflecting more long-term effects like vegetation and soil chemistry showed a stronger differentiation between drained and rewetted states than variables with a more immediate reaction to environmental change, like greenhouse gas (GHG) emissions. Variations in microbial community composition explained differences in soil chemical data as well as vegetation composition and GHG exchange. We show the importance of developing an integrative understanding of managed fen peatlands and their ecosystem functioning.