Effects of benthic macroinvertebrates on the exchange of solutes between sediments and freshwater

Abstract

lnfaunal macrobenthos (tubificid oligochaetes, chironomid larvae, and unionid bivalves) were studied in laboratory microcosms to determine their effects on freshwater sediment diagenesis and the exchange of solutes between sediments and water. Tubificids enhanced the flux of ammonium, bicarbonate, and silica from sediments. After the onset of anoxia, they decreased the flux of iron and phosphate. Chironomids increased the flux of nitrate, bicarbonate, and silica, but did not affect the flux of phosphate. Pore water concentrations were low within the irrigated burrowed zone for chemical species normally high in reduced sediments. Concentration gradients were less steep in the actively irrigated burrow zone, but radial diffusion to and from burrows, increased rates of organic decomposition, and enhanced diatom frustule dissolution rates result in enhanced mass transport from sediments. Data from an experiment with unionid clams demonstrated the presence of radial diffusion gradients. These clams enhanced the chloride and nitrate flux from sediments, decreased the bicarbonate flux, but did not affect the flux of either phosphate or silicate. Although the clams did not actively irrigate their burrows, their effect on sediments was similar t o that of chironomids. Comparison of direct and indirect flux estimates showed that both types of estimates could be highly variable. In general, indirect flux estimates were higher than direct flux estimates.

The impact of sediment bioturbation by secondary organisms on metal bioavailability, bioaccumulation and toxicity to target organisms in benthic bioassays: Implications for sediment quality assessment

“…The bioturbation of sediments by large benthic invertebrates alters sediment redox chemistry by mixing pre-stratified zones in the sediment, and increasing the penetration of electron acceptors such as dissolved O 2 , NO 3 -and SO 4 2-into anoxic sediments (Aller et al, 2001;Granéli, 1979;Matisoff et al, 1985;Pischedda et al, 2008;Volkenborn et al, 2010). Redox changes can alter metal binding affinities between the solid and dissolved phases, significantly modifying the speciation and bioavailability of most metals in sediments (De Jonge et al, 2012;Doyle and Otte, 1997;Granberg et al, 2008).…”

Biodiversity Loss in Freshwater Mussels: Importance, Threats, and Solutions

“…Mussels also act as environmental engineers, bioturbating the sediment as they move both vertically and horizontally (Allen and Vaughn, 2011). This activity can increase the depth of oxygen penetration in the sediment, homogenize sediment particle size (McCall et al, 1995), and affect the flux rates of solutes between the sediment and water column (Matisoff et al, 1985).…”

Influence of tubificid worms on nutrient fluxes across water-sediment interface in fish farm settling ponds

“…Bioturbation induces changes on the bio-geo-chemistry at the water-sediment interface (changing even the physical structure of the sediment) via fluid advection, solute diffusion or sediment slumping (Aller, 1994;Navel et al, 2011;. Moreover, benthic organisms may not only enhance bacterial activity (Krantzberg, 1985, and references therein) but also promote the downward transport of oxygen and other electron acceptors Overall, the effect of bioturbation on the bio-geo-chemical processes occurring at the water-sediment interface depends not only upon the physical and chemical characteristics of the sediment (Gerino et al, 2003;Mermillod-Blondin and Rosenberg, 2006;) but also on the type of benthic organism (Matisoff et al, 1985;Zhang et al, 2010). Tubificid worms belong 12p2 to the functional group of upward-conveyors (or conveyor-belt species) (François et al, 2002;Gerino et al, 2003).…”