Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are impor- tant mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macro- fauna stimulates microbial nutrient dynamics through differ- ent types of animal-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen (mainly nitrate and ammo- nium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrifica- tion and denitrification, which together allows fixed nitrogen removal. However, the release of ammonium from sediments is enhanced more strongly than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna on ben- thic microbes apparently has small or neutral effects on ni- trogen cycling. Animal-microbe symbioses provide abun- dant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies reveal that ecosys- tem engineering, grazing, and symbioses of benthic macro- fauna significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitro- gen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macro- fauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of ni- trogen.
Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications
Published 2013 in Biogeosciences
ABSTRACT
PUBLICATION RECORD
- Publication year
2013
- Venue
Biogeosciences
- Publication date
2013-12-02
- Fields of study
Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar
CITATION MAP
EXTRACTION MAP
CLAIMS
- No claims are published for this paper.
CONCEPTS
- No concepts are published for this paper.