Spatial and Temporal Oxygen Dynamics in Macrofaunal Burrows in Sediments: A Review of Analytical Tools and Observational Evidence

The availability of benthic O-2 plays a crucial role in benthic microbial communities and regulates many important biogeochemical processes. Burrowing activities of macrobenthos in the sediment significantly affect O-2 distribution and its spatial and temporal dynamics in burrows, followed by alterations of sediment microbiology. Consequently, numerous research groups have investigated O-2 dynamics in macrofaunal burrows. The introduction of powerful tools, such as microsensors and planar optodes, to sediment analysis has greatly enhanced our ability to measure O-2 dynamics in burrows at high spatial and temporal resolution with minimal disturbance of the physical structure of the sediment. In this review, we summarize recent studies of O-2-concentration measurements in burrows with O-2 microsensors and O-2 planar optodes. This manuscript mainly focuses on the fundamentals of O-2 microsensors and O-2 planar optodes, and their application in the direct measurement of the spatial and temporal dynamics of O-2 concentrations in burrows, which have not previously been reviewed, and will be a useful supplement to recent literature reviews on O-2 dynamics in macrofaunal burrows.