Effects of the polychaetes Arenicola marina and Nereis diversicolor on microbial pyrene mineralization

Abstract

The effects of 2 polychaetes, Nereis diversicolor and Arenicola marina, on the microbial mineralization of the organic contaminant pyrene, a polycyclic aromatic hydrocarbon (PAH), were followed over 44 d. We also examined whether the effect of the polychaetes was caused by enhanced oxygen supply, altered pyrene bioavailability and/or a changed abundance or activity of pyrenedegrading bacteria. The presence of polychaetes enhanced microbial pyrene mineralization by 180 to 200% compared with defaunated sediment. Collectively, the replicates of the different treatments showed that mineralization rates were positively correlated with the amount of oxidized sediment, which comprised mainly the 3 mm surface layer and zones around burrows (burrow sediment). The biogenic sediment structures had similar mineralization potential and abundance of pyrene-degrading bacteria as surface sediments. Pyrene mineralization potential in bulk (reduced and presumably anoxic) sediment was significantly lower than for surface and burrow sediments. However, when the bulk sediments were oxidized, mineralization rates increased rapidly. Collectively, these data indicate that oxygen availability controlled pyrene mineralization in these experiments. On the other hand, the presence of the polychaetes significantly reduced the bioavailability of pyrene to the microbial degraders. Pyrene bioavailability in burrow sediment was always lower than the bioavailability in both surface and bulk sediments. In addition, N. diversicolor and especially A. marina decreased the bioavailability of pyrene in surface sediments compared with that of surface sediments in the non-bioturbated control. In conclusion, these polychaetes enhanced microbial pyrene mineralization significantly and this enhancement seemed to be caused by the increased oxygen supply due to burrow construction and irrigation. In contrast, these worms decreased pyrene bioavailability and, hence, counteracted to some extent the stimulating effect of irrigation.

Changes of benthic bacteria and meiofauna assemblages during bio-treatments of anthracene-contaminated sediments from Bizerta lagoon (Tunisia)

“…An increase of nematode abundance resulted in higher organic matter mineralization (Nascimento et al 2012). It has been reported that the presence of polychaetes enhanced microbial pyrene mineralization, probably by increasing oxygen supply due to burrow ventilation (Timmermann et al 2008). In contrast, it was found that the increase of nematode abundance resulted in an increase of hydrocarbonoclastic bacteria grazing and therefore a decrease of PAH degradation efficiency (Naslund et al 2010).…”

Benzo(a)pyrene inhibits the role of the bioturbator Tubifex tubifex in river sediment biogeochemistry

“…It has been demonstrated that oxygen concentrations have a predominant role on the fate of PAHs since the degradation of PAH by microorganisms is much more efficient under aerobic conditions than under anaerobiosis (Boyd et al, 2005;Quantin et al, 2005;Haritash and Kaushik, 2009). Therefore, bioirrigation of sediments by benthic fauna can stimulate PAH degradation through continuous or periodical increase of oxygen availability in anaerobic sediments (Granberg et al, 2005;Timmermann et al, 2008;Montgomery et al, 2008;Cuny et al, 2011). In the present study, we did not detect a stimulation of benzo(a)pyrene loss due to the bioirrigation activity of T. tubifex.…”

Oil spill effects on macrofaunal communities and bioturbation of pristine marine sediments (Caleta Valdés, Patagonia, Argentina): experimental evidence of low resistance capacities of benthic systems without history of pollution

“…Indeed, bioturbation processes such as burrow construction and ventilation carried out mainly by macrofauna are key process to stimulate the availability of oxygen in superficial sediments (Timmermann et al 2008). In addition, some macrobenthic organisms can affect positively the biodegradation of hydrocarbons through the production of digestive compounds acting like surfactants that modify their dispersion state and improve their bioavailability (Penry and Weston 1998;Weston and Mayer 1998;Gilbert et al 2001) for hydrocarbon-degrading bacteria (Bertrand et al 1993;Bonin and Bertrand 1999;Cuny et al 2007;Cuny et al 2011).…”