Abstract
In soft-bottom sediments, consumers may influence ecosystem function more via engineering that alters abiotic resources than through trophic influences. Understanding the influence of bioturbation on physical, chemical, and biological processes of the water-sediment interface requires investigating top-down (consumer) and bottom-up (resource) forces. The objective of the present study was to determine how consumer bioturbation mode and sediment properties interact to dictate the hydrologic function of experimental filtration systems clogged by the deposition of fine sediments. Three fine-grained sediments characterized by different organic matter (OM) and pollutant content were used to assess the influence of resource type: sediment of urban origin highly loaded with OM and pollutants, river sediments rich in OM, and river sediments poor in OM content. The effects of consumer bioturbation (chironomid larvae vs. tubificid worms) on sediment reworking, changes in hydraulic head and hydraulic conductivity, and water fluxes through the water-sediment interface were measured. Invertebrate influences in reducing the clogging process depended not only on the mode of bioturbation (construction of biogenic structures, burrowing and feeding activities, etc.) but also on the interaction between the bioturbation process and the sediments of the clogging layer. We present a conceptual model that highlights the importance of sediment influences on bioturbation and argues for the integration of bottom-up influence on consumer engineering activities.
| Original language | English |
|---|---|
| Pages (from-to) | 125-138 |
| Number of pages | 14 |
| Journal | Oecologia |
| Volume | 161 |
| Issue number | 1 |
| DOIs | |
| State | Published - Aug 2009 |
Funding
Acknowledgments This work was a part of the OTHU project (Experimental Observatory for Urban Hydrology) and was funded by the urban community of Lyon (COURLY) and the Rhône-Alpes region. This study was also supported by the Institut National des Sciences de l’Univers (n°03N51/0532, programme ECCO-PNBC) within the project Urbanization and stormwater pollution: impact on biological activities and biogeochemical functioning of water–sediment interfaces, and by the Agence Nationale de la Recherche (no. ANR-06-BDIV-007, programme Biodiversité) within the InBio Process project. The experiments comply with the current laws of the country in which they were performed. We thank J.-P. Bedell, J.-C. Boisson, and B. Montuelle for fruitful discussions concerning experimental results; M. Creuzé Des Châtelliers for the collection of invertebrates; G. Bouger and A. Ohannessian for their help during sediment and water sampling; and P. Marmonier for his comments that improved the final version of this paper. We are also grateful to Pete Peterson, Rutger Rosenberg and one anonymous reviewer for their insightful comments.
| Funder number |
|---|
| 03N51/0532 |
Keywords
- Bottom-up influences
- Clogging
- Hydraulic conductivity
- Invertebrates
- Top-down influences
