At a proximal level, the physiological impacts of global climate change on ectothermic organisms are manifest as changes in body temperatures. Especially for plants and animals exposed to direct solar radiation, body temperatures can be substantially different from air temperatures. We deployed biomimetic sensors that mimic the thermal characteristics of intertidal mussels at 66 sites worldwide, from 1998-present. Loggers recorded temperatures at 10-15 minute intervals nearly continuously at multiple intertidal elevations. Comparisons against direct measurements of mussel tissue temperature suggest errors of ~2.0-2.5°C, during daily fluctuations that often exceed 15°-20°C. Geographic patterns in thermal stress based on biomimetic logger measurements were generally far more complex than anticipated based only on “habitat” level measurements, and show that animals are reaching temperatures far above air temperature on sunny days. This unique data set provides a means of assessing spatial and temporal variability in intertidal thermal stress, and links physiological measurements to field patterns.
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