The anatomy of the intertidal thermal profile (from the usual to the extreme and the odd)Broad-scale Spatial Patterns

Rui Seabra¹, Cátia Monteiro¹, Rita da Silva¹, Rocio Nieto-Vilela¹, Fernando P. Lima¹

¹University of Porto, Portugal

Temperature is one of the most important abiotic factors determining which species exist where and when. It has important implications for the physiology of organisms, controlling metabolic rates, reproduction cycles, biological interactions, and many other aspects throughout an organism’s entire lifespan.

In the intertidal zone of rocky shores, organisms are cyclically exposed to marine and terrestrial conditions that generate some of the most spatiotemporally complex thermal landscapes of any ecosystem. While this complexity has long been recognized, technological limitations have been preventing the long-term monitoring of rocky shore temperatures at the scales that really matter to the organisms, in turn limiting our understanding of the exact thermal conditions they have to endure.

The CCTBON (Coupled Coastal Temperature and Biodiversity Observation Network) is a groundbreaking project monitoring temperature in rocky shore ecosystems across the entire Atlantic Ocean. Temperature is being recorded continuously on hundreds of rocky shores from Pole to Pole, in some locations since 2010. At least 6 temperature loggers have been installed in sun-exposed and shaded microhabitats at all sites, allowing for the determination of each shore’s thermal envelope.

Drawing from that dataset, this presentation will provide a comprehensive overview of intertidal thermal regimes across a wide range of climatic and oceanographic contexts. We will first focus on describing how temperature flows during a typical sunny day at a typical rocky shore and then use examples from the tens of thousands of days recorded by in situ CCTBON temperature loggers to visually illustrate how thermal profiles are affected by i) solar exposure, ii) shore topographical heterogeneity, iii) limits to warming/cooling rates, iv) the timing of the tides, and v) storms, heatwaves, and cold snaps, as well as showcase examples of patterns that may be counterintuitive to most intertidal ecologists.