Faculty of Technical Sciences

TY - JOUR

T1 - Partitioning benthic nitrogen cycle processes among three common macrofauna holobionts

AU - Zilius, Mindaugas

AU - Daunys, Darius

AU - Bartoli, Marco

AU - Marzocchi, Ugo

AU - Bonaglia, Stefano

AU - Cardini, Ulisse

AU - Castaldelli, Giuseppe

N1 - Publisher Copyright: © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

PY - 2021/10/15

Y1 - 2021/10/15

N2 - The effects of single macrofauna taxa on benthic nitrogen (N) cycling have been extensively studied, whereas how macrofaunal communities affect N-related processes remains poorly explored. In this study, we characterized benthic N-cycling in bioturbated sediments of the oligotrophic ore Estuary (northern Baltic Sea). Solute fluxes and N transformations (N-2 fixation, denitrification and dissimilative nitrate reduction to ammonium [DNRA]) were measured in sediments and macrofauna-associated microbes (holobionts) to partition the role of three dominant taxa (the filter feeder Limecola balthica, the deep deposit feeder Marenzelleria spp., and the surface deposit feeder Monoporeia affinis) in shaping N-cycling. In the studied area, benthic macrofauna comprised a low diversity community with dominance of the three taxa, which are widespread and dominant in the Baltic. The biomass of these taxa in macrofaunal community explained up to 30% of variation in measured biogeochemical processes, confirming their important role in ecosystem functioning. The results also show that these taxa significantly contributed to the benthic metabolism and N-cycling (direct effect) as well as to sediments bioturbation with positive feedback to dissimilative nitrate reduction (indirect effect). Taken together, these functions promoted a reuse of nutrients at the benthic level, limiting net losses (e.g. denitrification) and effluxes to bottom water. Finally, the detection of multiple N transformations in macrofauna holobionts suggested a community-associated versatile microbiome, however, its role was of minor importance as compared to the activity of sediment-associated microbial communities. The present study highlights hidden and interactive effects among microbes and macrofauna, which should be considered analysing benthic functioning.

AB - The effects of single macrofauna taxa on benthic nitrogen (N) cycling have been extensively studied, whereas how macrofaunal communities affect N-related processes remains poorly explored. In this study, we characterized benthic N-cycling in bioturbated sediments of the oligotrophic ore Estuary (northern Baltic Sea). Solute fluxes and N transformations (N-2 fixation, denitrification and dissimilative nitrate reduction to ammonium [DNRA]) were measured in sediments and macrofauna-associated microbes (holobionts) to partition the role of three dominant taxa (the filter feeder Limecola balthica, the deep deposit feeder Marenzelleria spp., and the surface deposit feeder Monoporeia affinis) in shaping N-cycling. In the studied area, benthic macrofauna comprised a low diversity community with dominance of the three taxa, which are widespread and dominant in the Baltic. The biomass of these taxa in macrofaunal community explained up to 30% of variation in measured biogeochemical processes, confirming their important role in ecosystem functioning. The results also show that these taxa significantly contributed to the benthic metabolism and N-cycling (direct effect) as well as to sediments bioturbation with positive feedback to dissimilative nitrate reduction (indirect effect). Taken together, these functions promoted a reuse of nutrients at the benthic level, limiting net losses (e.g. denitrification) and effluxes to bottom water. Finally, the detection of multiple N transformations in macrofauna holobionts suggested a community-associated versatile microbiome, however, its role was of minor importance as compared to the activity of sediment-associated microbial communities. The present study highlights hidden and interactive effects among microbes and macrofauna, which should be considered analysing benthic functioning.

KW - Benthic functioning

KW - Invertebrate-microbe associations

KW - Nitrogen cycle

KW - Nitrate reduction

KW - Sediments

KW - Baltic Sea

KW - MONOPOREIA-AFFINIS

KW - POPULATION-DYNAMICS

KW - ECOSYSTEM FUNCTION

KW - NITRATE REDUCTION

KW - NUTRIENT FLUXES

KW - SHELL BIOFILM

KW - DENITRIFICATION

KW - BIOTURBATION

KW - MARINE

KW - SEDIMENTS

U2 - 10.1007/s10533-021-00867-8

DO - 10.1007/s10533-021-00867-8

M3 - Journal article

VL - 157

SP - 193

EP - 213

JO - Biogeochemistry

JF - Biogeochemistry

SN - 0168-2563

ER -