Stimulation of decomposition of Spartina anglica leaves by the bacterivorous marine nematode Diplolaimelloides bruciei (Monhysteridae)

Experimental evidence for the role of bioturbation by the marine nematode Diplolaimella dievengatensis in stimulating the mineralization of Spartina anglica detritus

“…In the presence of Monhystera disjuncta increased weight losses of seaweed detritus were found by Rieper-Kirchner (1989). In a previous study we found an increased mineralization of organic carbon and increased weight losses of Spartina anglica leaves in the presence of Diplolairnelloides bruciei (Alkemade et al 1992).…”

“…Culture dishes containing bacto-agar, Vlasblom-medium and Na2Si03.9H20 were inoculated with 10 to 20 adult specimens of D. dievengatensis and a droplet of filtered (1.2 pm) seawater. Before inoculating the nematodes onto the culture dishes an extra transfer step was performed in order to avoid contamination by ciliates and other protozoa (Alkemade et al 1992).…”

“…The petri dishes were incubated at 20 "C, in the dark, in an air-tight chamber (20 ml) for l to 4 h (dependent on the CO2 production in the dish). CO2 and O2 concentrations in the incubation chambers were measured before and after incubation by injecting air samples on a Packard 427 gas chromatograph (details in Alkemade et al 1992). The CO2 and O2 flux are expressed as the CO, production and O2 consumption per m* per hour.…”

Micro-trace fossils reveal pervasive reworking of Pliocene sapropels by low-oxygen-adapted benthic meiofauna

“…Thus, high-resolution imaging of these Pliocene sapropels shows, for the first time, that comprehensive meiofaunal reworking of organically enriched ancient sediments can occur under low-oxygen, sulfidic conditions prohibitive of macrofaunal metazoan life, consistent with studies of modern sediments showing the ubiquity and dominance of a meiofaunal 'thiobios' in equivalent environments 10 . These data does not quantify the changes in organic carbon between ingested and uningested sediment, but studies of modern sediments show that meiofaunal activity exerts an important influence on sediment biogeochemistry, including increased mineralization of sedimentary OM [14][15][16] . Independent of a direct digestive or enzymatic influence, the extent of meiofaunal burrowing observed in the sapropels implies increased pore-water exchange and solute diffusion relative to undisturbed laminated intervals 16,20 .…”

“…Although they navigate around sand grains, they ingest the finest, most chemically reactive sediment fraction 10 and have an impact on sediment biogeochemistry similar to the macrofauna. For example, meiofaunal burrowing stimulates the decomposition of sediment OM [14][15][16] , increases microbial growth 17 and produces a dense net of fine burrows 18,19 that increase solute transport between 1.7-and 3.6-fold relative to molecular diffusion 16,20,21 , increase sulfide oxidation 10 and shorten pore-water turnover to only 1-3 years 18 . Adaptations, such as reduced size, small crosssection allowing efficient oxygen diffusion and navigation between large grains, high sulfide tolerance and low metabolic needs for oxygen, allow certain meiofauna to prosper where macrofauna do not 10 .…”