Alternate Title

Effects of the Burrowing Brittlestar, Microphiopholis gracillima (Echinodermata: Ophiuroidea), on the Flux of Lithium, an Inert Tracer, Across the Sediment-Water Interface

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Burrowing and ventilation activities of infaunal organisms have been shown to affect geochemical processes in sediments and at the sediment-water interface. Although burrowing brittlestars are dominant in many benthic environments, their role in these processes is poorly known. We tested the effect of the amphiurid brittlestar, Microphiopholis gracillima, on the flux of lithium ion from the sediment to the overlying water by using sediment cores with false bottoms for continuous flow of a Li+1-seawater solution. Brittlestars at densities of 300 and 600 individuals m-2 caused a twofold increase in the rate that Li was transported through the sediment. Density of brittlestars appeared to have no effect on the flux of Li+1 from the sediment, indicating a possible threshold beyond which density increases do not influence fluxes of solute from the sediment.

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