From Space to the Rocky Intertidal: Measuring the Body Temperature of the Intertidal Mussel Species, Mytilus californianus using NASA MODIS Surface Temperatures

The California mussel, Mytilus californianus, is an ecologically important species in the rocky intertidal ecosystems of the U.S. Pacific coast. During low tides, times of emersion, Mytilus californianus is exposed to aerial conditions and its body temperature can vary drastically depending on the amount of solar radiation they experience. Thermal stress from high temperatures during emersion sometimes can lead to mortality of individuals. Conversely, during high tides, times of submersion, body temperatures depend on the temperature of the water that surrounds them. This study used remotely sensed surface temperature observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Earth Observing System (EOS) Aqua and Terra to predict the body temperatures of Mytilus californianus. Mussel body temperatures were provided by the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) and de-tided. This technique divided the mussel body temperatures into times of emersion and times of submersion. During times of emersion, mussel body temperatures were compared to remotely sensed land surface temperatures (LST) and in-situ air temperatures. During times of submersion, mussel body temperatures were compared to remotely sensed sea surface temperatures (SST) and in-situ water temperatures. To identify spatial variation in temperatures, eight different study sites ranging in latitude along the coast of Oregon were analyzed. Additionally, to better understand the temporal variation in temperatures, fourteen years (2000-2013) were analyzed for each study site. Sea surface temperature collected during the Aqua overpass and Terra overpass were strongly correlated with mussel body temperatures but varied by study site. Our results show that remotely sensed temperature could predict average daily mussel temperature within 1°C on average during times of submersion. Being able to use remotely sensed surface temperatures to predict the body temperatures of intertidal mussel species will enhance our ability to predict the effects of climate change on intertidal ecosystems. Additionally, it will lead to more research that investigates using remotely sensed observations to understand dynamics in other ecosystems beside the rocky intertidal.