The rocky intertidal zone is a highly dynamic and thermally variable ecosystem, where the combined influences of solar radiation, air temperature and topography can lead to differences greater than 15°C over the scale of centimetres during aerial exposure at low tide. For most intertidal organisms this small-scale heterogeneity in microclimates can have enormous influences on survival and physiological performance. However, the potential ecological importance of environmental heterogeneity in determining ecological responses to climate change remains poorly understood. We present a novel framework for generating spatially explicit models of microclimate heterogeneity and patterns of thermal physiology among interacting organisms. We used drone photogrammetry to create a topographic map (digital elevation model) at a resolution of 2 × 2 cm from an intertidal site in Massachusetts, which was then fed into to a model of incident solar radiation based on sky view factor and solar position. These data were in turn used to drive a heat budget model that estimated hourly surface temperatures over the course of a year (2017). Body temperature layers were then converted to thermal performance layers for organisms, using thermal performance curves, creating 'physiological landscapes' that display spatially and temporally explicit patterns of 'microrefugia'. Our framework shows how non-linear interactions between these layers lead to predictions about organismal performance and survivorship that are distinct from those made using any individual layer (e.g. topography, temperature) alone. We propose a new metric for quantifying the 'thermal roughness' of a site (RqT, the root mean square of spatial deviations in temperature), which can be used to quantify spatial and temporal variability in temperature and performance at the site level. These methods facilitate an exploration of the role of micro-topographic variability in driving organismal vulnerability to environmental change using both spatially explicit and frequency-based approaches.
Bibliographical noteFunding Information:
F.C., T.G. and B.H. were supported by a grant from the National Science Foundation (OCE-1635989). G.R. was funded by the Israeli Binational Science Foundation.
F.C., T.G. and B.H. were supported by a grant from the National Science Foundation (OCE-1635989). G.R. was funded by the Israeli Binational Science Foundation. F.L. and R.S. were supported by FEDER - European Regional Development Fund (Fonds Européen de Développement Économique et Régional) through COMPETE - Operational Programme Factors of Competitiveness (“Programa Operacional Factores de Competitividade”) and by the Portuguese Foundation for Science and Technology (FCT - Fundação para a Ciência e a Tecnologia").
© 2019 The Author(s). Published by Oxford University Press and the Society for Experimental Biology.
- environmental heterogeneity
- intertidal zone
ASJC Scopus subject areas
- Ecological Modeling
- Nature and Landscape Conservation
- Management, Monitoring, Policy and Law