Abstract

Traditionally meiofauna have been viewed as strictly infaunal organisms adapted for life between sediment grains. Recent evidence has shown that marine meiofauna also occur in the water column. A set of field experiments investigated processes controlling the abundance of meiofauna in the water column. The transport of meiofauna in a tidal creek was identified to be primarily a passive process resulting from mechanical removal due to current scour. Drifting meiofauna included interstitial, burrowing, and epibenthic species. Copepods, foraminiferans, and juvenile bivalves were suspended in greatest numbers relative to their sediment abundances. Suspension of meiofauna was greatest for species residing in the upper sediment layers and/or occasionally crawling about on the sediment surface. Suspended meiofauna and sediment were well-mixed within the water column, suggesting that behavioral control over water column dispersal was limited once the animals were in the water. Suspension of meiofauna was not a function of winds, time of day, lunar cycle (neap vs. spring tides), or the abundance of meiofauna in the sediment. The abundance of meiofauna in the water was determined primarily by the magnitude of the friction velocity (u.). The emerging concept is that in habitats where water currents are strong enough to lead to sediment scour, meiofauna dispersal is a two-step process with erosion rather than active water column entry (modified by behavior patterns for some species) and subsequent mixing and transport as passive particles.

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