Impact of Arenicola marina (Polychaeta) on sediment sulfur dynamics

Abstract

Sulfate reduction rates and various parameters related to the sulfur cycling were investigated in situ and experimentally by a mm approach in sediment surrounding burrows of the polychaete Arenicola marina. Sulfate reduction rates were immediately affected in a 5 to 15 mmthick zone surrounding the tail shaft. Rates were depressed by 52% in the burrow wall and increased with distance towards ambient rates. Experimental use of artificially ventilated burrows showed that the reduction was mediated by introduction of oxygenated surface water by irrigation, which suppressed possible stimulating effect of increase in organic carbon availability from mucus secretion by the worm. Furthermore, irrigation and sediment reworking by A. marina increased the content of biological reactive Fe(III) in the feeding funnel and in a narrow zone around the tail shaft, creating environments suitable for dissimilative Fe(III) reduction. Total reduced sulfide pools showed that reoxidation of reduced sulfide species occurred along the burrow and in the feeding funnel of A. marina. Reoxidation in the tail shaft region was mediated by irrigation, while the reduction in the feeding funnel probably occurred due to the combined effect of irrigation and sediment reworking. In general, A. marina has a great impact on sediment sulfur biogeochemistry, suggesting that bioturbation depresses sulfate reduction and increases the importance of Fe(III) as an electron acceptor in carbon oxidation. It is also indicated that A. marina reduces permanent burial of reduced sulfide and lowers the steady-state level of total reduced sulfide in the sediment.

Sulfur, carbon, and nitrogen cycling in faunated marine sediments impacted by repeated organic enrichment

“…While irrigation translocates oxygen into otherwise anoxic sediment (Kristensen 2001, Nielsen et al 2003, reworking mediates downward mixing of surfacedeposited OM into deeper anoxic layers and vice versa (Aller 1994, Kristensen & Mikkelsen 2003, Papaspyrou et al 2004. Irrigation is thus frequently linked to enhanced OM mineralization, whereas reworking activities have been linked to both enhanced mineralization of indigenous OM and hampered mineralization of recently deposited OM (Aller & Aller 1998, Kristensen & Holmer 2001.…”

“…The impact of bioturbation on S cycling in organically enriched sediments is not well documented. The rapid oxidation of total reduced inorganic sulfides (TRIS) observed upon introduction of infauna suggests that bioturbation is vital for regeneration of the TH 2 S buffering capacity (Heilskov & Holmer 2003, Nielsen et al 2003. Furthermore, irrigation may lower the importance of SR for total C oxidation (Banta et al 1999, Heilskov & Holmer 2001 and TRIS precipitation may thus be lower in faunated as opposed to defaunated sediments (Chareonpanich et al 1994, Banta et al 1999).…”

“…Alternatively, the generally observed mosaic of oxic and anoxic microniches in bioturbated sediments (Fenchel 1996, Kristensen 2000, Nielsen et al 2003 may have prevented TRIS formation due to small-scale Fe 2+ or TH 2 S limitation. In any case, the level of TRIS precipitation was 18% higher than observed in diffusion-controlled defaunated sediment (Fig.…”

Microscale distribution of oxygen and nitrate in sediment inhabited by Nereis diversicolor: spatial patterns and estimated reaction rates

“…Although they are known as biogeochemical hot-spots with high organic loading, bacterial numbers, and activity (Kristensen 1988, Reichardt 1988, Hansen et al 1996, Phillips & Lovell 1999, relatively few studies have quantified and located biogeochemical reactions in the vicinity of the infaunal burrows. Direct measurements in the sediment immediately surrounding burrow structures have shown that this unique environment increases oxygen consumption (Binnerup et al 1992), hampers sulfate reduction rates (Gribsholt et al 2003, Nielsen et al 2003 and increases potential nitrification and denitrification (Kristensen 1985, Mayer et al 1995 compared to the surrounding sediment. In the past, nitrification denitrification processes in sediment surrounding burrow structures were measured from coarsely dissected burrows (low resolution) followed by slurry incubation (Kristensen 1985, Mayer et al 1995 or by modeling similar coarse profiles of nitrate (Aller 1988).…”

Effects of the bioturbating lugworm Arenicola marina on the structure of benthic protistan communities

“…Lugworms are abundant on intertidal flats in the Wadden Sea, where they create up to 40 cm deep Jshaped blind-ending burrows (Riisgård & Banta 1998). Lugworm bioturbation has significant effects on many sedimentary processes, including stratification (Baumfalk 1979), pore water characteristics (Hüttel 1990, Volkenborn et al 2007a, sediment biogeochemistry (Banta et al 1999, Kristensen 2001, Nielsen et al 2003, microbial communities (Reichardt 1988, Grossmann & Reichardt 1991, Retraubun et al 1996, meiobenthic communities (Reise & Ax 1979, Reise 1987, Kuhnert et al 2010, Lei et al 2010, and macrobenthic communities (Reise 1983, Flach 1992, Volkenborn & Reise 2006, Valdemarsen et al 2011. The potential impact of lugworms on the protistan community is expected to be manifold and include direct trophic effects and indirect sediment-mediated effects.…”