MarHot - Bridging experimental and modelling approaches to predict marine native and invasive hotspots under climate change
The amplitude and frequency of extreme events, such as marine heatwaves, are increasing with climate change in the European temperate coasts. As a consequence, macroalgae and seagrasses are shifting their ranges, which implies significant impacts on marine ecosystems. The loss of native foundational species will also open windows of opportunity for invasive species, a major threat to Europe's biodiversity that has social and economic impacts. However, our ability to predict the future distribution of marine habitat-forming species under climate change is yet limited.
Correlative species distribution models (SDMs) are useful tools to predict the future distribution of coastal canopy-forming species. Recently, physiological thermal limits obtained from mesocosm experiments have been combined with SDMs to produce more consistent predictions in the form of mechanistic or hybrid models. However, mechanistic models remain mostly untested and the existing approaches do not provide an efficient tool to produce multi-species mechanistic models suitable to identify hotspots of species at risk of extinction and hotspots for invasive macrophytes.
MarHot outputs will benefit society because it is a direct contribution to achieving the Development Goals and Biodiversity regulations adopted by the European Union. Finally, MarHot project has helped placing its researchers and the EU at the forefront of innovation in climate change research, paving the way for further progress in biodiversity conservation.
Objectives of MarHot have been to (i) provide an innovative framework to integrate physiological thermal limits into SDMs in order to anticipate future redistributions of marine coastal species, thanks to an interdisciplinary collaborative research and cutting-edge mesocosms set-ups provided by the host institutions; (ii) investigate innovative approaches to constrain SDM outputs with experimental evidence; (iii) explore multi-species range shifts in response of marine heatwaves. MarHot takes advantage of recent analytical tools to detect extreme thermal events and the increasing availability of global databases on thermal tolerance limits. The project will provide an analytical framework in open source software for analyses of coastal macrophyte hotspots under future scenarios of marine heatwaves. The scientific community will be able to use the developed tools to reproduce the analytical approach with other species.
MarHot has provided new avenues to the understanding of marine redistributions through a workflow facilitating the incorporation of unused variables related to temperature variability, while analyzing the distributions of coastal species. The use of metrics related to sea surface temperature variability to explain persistence and extinction of macroalgae populations is certainly innovative. In this project we argue that consideration of multiple thermal manifestations of climate change is needed to better understand local extirpations of habitat-forming species. Our study opens new avenues to the understanding of marine redistributions.
MarHot has also assessed the physiological responses of marine macrophytes to ocean warming and desiccation stress, using two sympatric algae with different cycles of immersion due to tides. This project’s experimental work has allowed us to obtain relevant physiological data to be integrated into species distribution models predictions in order to produce mechanistic or hybrid models.
