The complex effects of the invasive polychaetes Marenzelleria spp. on benthic nutrient dynamics

Abstract

The effects of the polychaetes Marenzelleria sp. (Polychaeta, Spionidae), nonindigenous, rapidly increasing species in the Baltic Sea, on benthic nutrient fluxes, denitrification and sediment pore water nutrient concentration were studied in laboratory experiments using a flow-through setup with muddy sediment from coastal regions of the Gulf of Finland. In addition, different forms of sediment phosphorus (P), separated by chemical fractionation, were studied in three sediment layers. At a population density corresponding to about half the highest measured in the northern Baltic Sea, Marenzelleria sp. increased the fluxes of P and ammonium to the water column. No effect could be recorded for denitrification. Since the previously dominant species of the area, Monoporeia affinis, can enhance denitrification and lower the amount of dissolved P in the pore water, the replacement of M. affinis with Marenzelleria spp. may lead to increased P flux to the water column and decreased denitrification, further increasing the ammonium flux to the water column. However, sediment reworking by Marenzelleria spp. also oxidizes the surface sediment in the long run, improving its ability to retain P and support nitrification. Therefore, the impact of Marenzelleria spp. on sediment nutrient release may not be as drastic as the initial reactions seen in our experiments suggest.

Indications of Recovery from Hypoxia in the Inner Stockholm Archipelago

“…This worm, tolerant to low oxygen levels, forms highly branched burrow networks deeper into to the sediment than most other common Baltic Sea macroinvertebrates (Hietanen et al 2007). It is, therefore, possible that the colonization of M. neglecta and its bioturbation activities seen in this study have improved sediment conditions below the sedimentwater interface more than what would have been the case if only native Baltic species had recolonized the area.…”

Are similar worms different? A comparative tracer study on bioturbation in the three sibling species Marenzelleria arctia, M. viridis, and M. neglecta from the Baltic Sea

“…The spreading of M. viridis is accompanied by decreasing populations of H. diversicolor , whereas M. neglecta is known for their competitive interactions with M. affinis (Kotta et al 2006). The invasion of the polychaetes has complex effects on nutrient dynamics (Hietanen et al 2007;Norkko et al 2011;Quintana et al in press) and eutrophication (Karlson et al 2007;Viitasalo-Frö sen et al 2009). In the Baltic Sea, where deep-burrowing species are naturally absent, the burrowing activity of Marenzelleria spp.…”

“…M. neglecta (Zettler et al 1994) and M. viridis (Essink and Kleef 1988;Quintana et al 2011) are known to construct L-, J-, or I-shaped, unbranched mucus-lined burrows to a sediment depth of 25-35 cm with a mean diameter of 2 mm. In contrast, M. arctia creates J-, Y-, or U-shaped burrows with a thin transparent membrane lining to a maximum depth of 6-8 cm (Hietanen et al 2007;own observation).…”

“…have been done so far, but Blank et al (2008) found incorrect species nominations in astonishingly 58% of all considered papers as a result of the difficulties in species discrimination. Due to the similarity in morphological characteristics, the sibling species are thought to have only minor, if any, functional differences (Hietanen et al 2007;Norkko et al 2011). Hence, little is known about species-dependent sediment reworking and solute transport, although size and burrowing depth of the organisms indicate differences.…”

Nutrient fluxes from reduced Baltic Sea sediment: effects of oxygenation and macrobenthos

“…Rather, the higher NO 2 + NO 3 (and DIN) fluxes in the presence of M. affinis compared to controls show that their potential influence on denitrification cannot compensate for their simultaneous stimulation of overall N mineralisation. Marenzelleria is known to have a minimal effect on benthic denitrification (Karlson et al 2005, Hietanen et al 2007 or to even diminish it (Bonaglia et al 2013). …”