Analysis of heatwaves in the coastal marine sediments of South Bay, VA
In a recent survey of leading researchers, Macreadie et al. (2019) identified fundamental questions needed to advance blue-carbon (BC) science. One of those questions relates to a need for better understanding of disturbance events in sediments as they will likely impact long-term BC storage. Furthermore, heatwaves are known to occur in the atmosphere and in the pelagic environment of vegetated coastal marine ecosystems, yet there has been no study of heatwaves in coastal marine sediments. This is likely due lack of long-term sediment temperature data, difficulty in predicting when and where heatwaves will occur, and that sediment temperature is often less variable than atmospheric and water temperature. However, as marine heatwave (MHW) events have doubled in duration in recent decades, are projected to increase in frequency, intensity, and spatial extent, and have been shown to co-occur with losses of BC and coastal marine vegetation, understanding if the thermal stress that MHW disturbances represent are transferred into sediments is critical for carbon mitigation strategies and predicting ecosystem resilience.
This study will establish a sediment temperature record suitable for assessing heatwaves in vegetated coastal marine sediments. This study will ask:
- do heatwaves occur in surficial sediments (5 cm depth) of a seagrass meadow?
- are there spatial differences in sediment heatwave characteristics related to greater oceanic exchange (i.e., meadow edge) that have lower thermal stress?
- did a MHW in June 2015 spur a sediment heatwave in South Bay where aboveground seagrass diebacks were observed in the central area of the meadow?