Contrasting effects of the polychaetes Marenzelleria viridis and Nereis diversicolor on benthic metabolism and solute transport in sandy coastal sediment

Abstract

The contrasting effects of the invasive Marenzelleria viridis and the native Nereis diversicolor on benthic metabolism, partitioning of reaction pathways and distribution of inorganic porewater (C and N) solutes in homogenized sandy sediment were investigated experimentally over a period of 1 mo. The 2 species were studied separately and in combination to observe possible effects and interactions. Benthic O 2 uptake and total CO 2 (TCO 2 ) release were affected similarly by M. viridis, N. diversicolor and the two in combination, with roughly a doubling after 1 to 2 wk compared to defaunated sediment. Sulfate reduction after 1 mo, on the other hand, was more than twice as high in sediment inhabited by M. viridis alone than in any other treatment, even when combined with N. diversicolor. Denitrification estimated from benthic TCO 2 release, porewater reaction stoichiometry and nutrient fluxes was largely unaffected by the presence of fauna. Accordingly, the partitioning of reaction pathways after 1 mo revealed that M. viridis stimulated sulfate reduction at the expense of aerobic respiration. Most of the oxygen uptake in M. viridis sediment was apparently due to enhanced oxidation resulting from an upward drifting front of sulfide as indicated by low redox and the appearance of Beggiatoa sp. near the surface. Porewater solute profiles showed that M. viridis was capable of stronger and deeper irrigation than N. diversicolor despite ~10 times higher burrow ventilation by the latter species. This effect was caused by percolation of return water in the deep (> 20 cm) I-or J-shaped burrows of M. viridis compared to the flushing of the more shallow (6 to 8 cm) U-shaped burrows of N. diversicolor. A replacement of the native N. diversicolor with the invasive M. viridis as the dominant burrow-dwelling polychaete in shallow coastal sediments will probably affect the biogeochemical functioning and ecological stability of the ecosystem. Among other things, organisms tolerant to sulfide are likely to be favored at the expense of more sensitive species.

Diverse effects of invasive ecosystem engineers on marine biodiversity and ecosystem functions: A global review and meta‐analysis

“…The effect of only one burrowing species on ecosystem functions was included in this analysis: those of the invasive burrowing polychaete worm, Marenzelleria viridis . The worm was shown to change the metabolism of the benthos by stimulating sulphate reduction at the expense of aerobic respiration (Kristensen, Hansen, Delefosse, Banta, & Quintana, ), as well as increasing benthic production (chlorophyll a ) due to higher biodeposition and/or bioturbation activity (Kotta, Orav, & Sandberg‐Kilpi, ; Laverock, Gilbert, Tait, Osborn, & Widdicombe, ). As shown by others, the effect of bioturbators in invaded ecosystems can be highly dependent on the local species composition and habitat structure (Queirós et al., ).…”

Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

“…Nitrification rates were increased in the presence of two Nereis species (Hansen and Kristensen, 1998;Nielsen et al, 2004;Kristensen et al, 1991) and not tested for any other polychaete species. With one exception (i.e., Marenzelleria viridis; Karlson et al, 2005), all polychaete species, including M. viridis tested in two other studies (Hietanen et al, 2007;Kristensen et al, 2011), increased denitrification rates often ca. 3-fold.…”

Burial and decomposition of plant pigments in surface sediments of the Baltic Sea: role of oxygen and benthic fauna

“…Granberg et al 2008for M. neglecta, Viitasalo-Frösén et al 2009 for Marenzelleria spp. and Kristensen et al 2011. showed experimentally that Marenzelleria spp.…”