Assessing the ecophysiological mechanisms underpinning thermal resilience in native and non-native shellfish in the Wadden Sea

The community composition and distribution of shellfish at mid to high latitudes may shift due to climate-driven warming as species better adapted to high temperatures have an increasing competitive advantage and new species from lower latitudes become established. In a warming Wadden Sea, changes to the composition and distribution of shellfish species may alter food web structure and the ecosystem services provided by bivalves. Shellfish populations are critical for enhancing biodiversity and are important to the trophodynamic structure and function of the Wadden Sea, and native mussels and cockles are experiencing increased die-off due to thermal stress. My aim is to unveil the ecophysiological mechanisms driving response to thermal stress in native mussel and cockle, and the newly introduced and plausible competitor: the nonnative Ruditapes philippinarum, known as the Manila clam. My hypothesis is that the newly introduced Manila clam in the Wadden Sea may spend less energy when coping with warming summer conditions than indigenous mussel and cockle species. The hypothesis will be tested in experiments using microsensors to quantify organismal-level energy use and physiological responses during simulated heatwaves (Figure 1). Ecophysiological responses will be measured through metabolic rate, heart rate, valve gap activity, respiration and nitrogenous excretion using various techniques including microsensors. These experiments will be conducted using the WUR CARUS facilities. The physiological responses will be used to parameterize dynamic energy budget (DEB) models. Patterns detected in the laboratory will then be tested in situ through field trials and surveys in the Wadden Sea. MaxEnt habitat suitability modeling and Graphab connectivity modeling will be used to incorporate mechanistic findings from the laboratory and environmental data to produce species distribution projections based on different scenarios of climate change severity.