Temperature effects on temperate seagrass metabolism and resilience

Seagrass meadows are metabolic hotspots in shallow coastal waters and are recognized as ‘blue carbon’ sinks. They are, however, increasingly threatened by climate change and other stressors. An eelgrass (Zostera marina) meadow at the Virginia Coast Reserve Long Term Ecological Research (VCR-LTER) site recently experienced a large-scale die-off, presumably caused by high summertime water temperatures, providing us with an unprecedented opportunity to study in situ seagrass response to thermal stress. This study examined spatial patterns of thermal stress and seagrass resilience in the meadow, as well as the direct effect of temperature on seagrass metabolism using the aquatic eddy covariance technique. This technique produces high-quality benthic metabolism measurements under naturally varying environmental conditions. It therefore allows us, for the first time, to observe the real-time metabolic response of eelgrass to high temperatures, and constrain the optimum temperature threshold for Z. marina under true in situ conditions. The results will provide insights into the potential responses of other temperate systems where warming oceans may lead to more frequent seagrass mortality events.