Table 2.
Selected conditions and processes influencing the ecological significance of the bacterial–viral loop in fluvial systems. Most factors are controlled by a continuum between physical and biological forces, with one or the other usually prevailing; important factors and environmental settings to be considered are listed
| Prevailing type of control | Factors to be considered | |
|---|---|---|
| Influenced by | ||
| Hydrology | Physical | Proportion of allochthonous/autochthonous material, general environmental setting |
| Unfavourable conditions | Physical | Temperature, hydrodynamics, mixing, stagnation |
| Trophic level | Biological | Productivity, nutrients, contact and virus propagation rates |
| Removal by particles/biofilms | Physical/biological | Current flow and turbulence, particle load and quality |
| Effect on | ||
| Local processing of OM | Biological | Availability of backwaters, retention zones, lentic water bodies |
| Horizontal transport (export) of OM | Physical | Flow regime, stream and river regulation, loss of habitat heterogeneity |
| Respiration, CO2 outgassing | Physical/biological | Surface area, floods, gas transfer velocity |
| Viral (host) diversity | Biological | Habitat heterogeneity, viral infectivity and lifestyles |
OM, organic matter.