CONTINUOUSLY MEASURED CHANGES IN REDOX POTENTIAL INFLUENCED BY OXYGEN PENETRATING FROM BURROWS OF CALLIANASSA-SUBTERRANEA

A continuously recording multiple redox sensor was used to measure oxygenation effects in otherwise anoxic sediments. The sensor reacted within three minutes (increase > 50 mV) to oxygen penetrating into the sediment. Different patterns of oxidation/reduction were observed along burrows of sediment-dwelling infauna. Examples of an increase of more than 600 mV lasting 50 hours and short, 1 to 4 hours long, oxidation pulses of approximately 280 mV increase are given. Redox patterns similar to the ones observed along natural burrows were generated using 'artificial burrows'. Oxygen penetrated up to 1 mm by diffusion from burrow walls into the adjacent sediment, whereas elevated Eh values were measured within 3 mm of the burrow. The oxygenation effect of a burrowing shrimp, Callianassa subterranea, was studied in a 3-month experiment with ten sensors and five animals. For one individual we recorded 108 events with Eh increasing by more than 300 mV. It was estimated that below every square meter of sediment surface 0.7 m2 burrow surface are subjected to oxygenation at least once per day by the population of Callianassa in the southern North Sea.