Are meiofauna transient or resident in the sand filters of a cold marine mesocosm?
Wat. Res. 15: 3625-3634 A paradoxical situation was found in the sand filters of a cold marine mesocosm: meiofaunal masses which were large enough to inhibit the mineralization and nitrification processes coexisted with nitrogen cycling bacteria. To test whether the copepod-dominated meiofauna was resident and actively feeding or transient and carried passively through the sand filters, mean residence times (MRTs) were measured for various meiofaunal groups in a newly started filter and in a long established one. MRTs were less than 20 minutes for most meiofaunal groups in the newly started filter. In contrast, they were 147 days for halacarids, 291 days for harpacticoid copepods and 1228 days for nematodes in the established filter. Mesocosm biofilm, occupying a large fraction of the mesocosm surface area and harboring high meiofaunal densities, was probably the main source of meiofauna in the sand filters.Pool sediments, gravel and sand were second to periphyton and contributed hydro
