Benthic macrofauna bioturbation and early colonization in newly flooded coastal habitats

Abstract

How will coastal soils in areas newly flooded with seawater function as habitat for benthic marine organisms? This research question is highly relevant as global sea level rise and coastal realignment will cause flooding of soils and form new marine habitats. In this study, we tested experimentally the capacity of common marine polychaetes, Marenzelleria viridis, Nereis (Hediste) diversicolor and Scoloplos armiger to colonize and modify the biogeochemistry of the newly established Gyldensteen Coastal Lagoon, Denmark. All tested polychaetes survived relatively well (28–89%) and stimulated carbon dioxide release (TCO2) by 97–105% when transferred to newly flooded soils, suggesting that soil characteristics are modified rapidly by colonizing fauna. A field survey showed that the pioneering benthic community inside the lagoon was structurally different from the marine area outside the lagoon, and M. viridis and S. armiger were not among the early colonizers. These were instead N. diversicolor and Polydora cornuta with an abundance of 1603 and 540 ind m-2, respectively. Considering the species-specific effects of N. diversicolor on TCO2 release and its average abundance in the lagoon, we estimate that organic carbon degradation was increased by 219% in the first year of flooding. We therefore conclude that early colonizing polychaetes modify the soils and may play an important role in the ecological and successional developments, e.g. C cycling and biodiversity, in newly flooded coastal ecosystems. Newly flooded soils have thus a strong potential to develop into well-functioning marine ecosystems.

Nitrogen and Phosphorus Export After Flooding of Agricultural Land by Coastal Managed Realignment

“…This artifact may explain the relatively high DIN and DIP fluxes observed from 2015 to 2019 compared to the soil loss and model calculations (Table 4). The initial first year rates of in situ DIN and DIP release from flooded soil to overlying water observed in the present study are comparable to those reported by Valdemarsen et al (2018) right after experimental flooding of darkened Gyldensteen soils.…”

A process based model of cohesive sediment resuspension under bioturbators' influence

“…Descriptions of ecosystem engineering have a particular relevance in predicting changes in landscape evolution (Pearce, 2011). Process-based models of bioturbation effects as those we presented may contribute to the prediction of both long and short-term morphodynamic trends (Hu, et al, 2015;Hu, et al, 2018) also as response to human modifications of coastal landscapes (Cozzoli, et al, 2017;Valdemarsen, et al, 2018). Having such a metabolismbased relationship does enable extrapolations on how change in benthic community metabolism may influence bioturbation effects on sediment resuspension.…”

Towards the creation of a marine protected area in the Aeolian Islands. Results of the 2018 Aeolian Expedition

“…These bioturbations may greatly affect biochemical processes, ecosystem functioning, and microbial activities in such sediments, due to modifi cations in the exchange rates of oxygen, carbon dioxide, and nutrients between the sediment and the overlying water. 83 During this research, habitats characterised by the presence of bioturbations were documented in four of the seven surveyed areas: Eolo seamount, North of Lipari, Secca dei Piesci and Stromboli. The species observed to form these bioturbations were Cepola macrophthalma, Goneplax rhomboides, Lesueurigobius spp.…”