It is widely accepted that biodiversity does address more than species richness and the equal distribution of species. At least four different aspects can be distinguished: genetic, structural, compositional, and functional diversity. It is particularly the latter that is of interest within the EU-funded project RUBICODE^[1], as functional diversity is likely to be linked to ecosystem processes and services, such as self purification and decomposition of organic matter in rivers.

Here, we address the calculation and evaluation of compositional and functional diversity of benthic macroinvertebrates in Central European lowland rivers. Functional aspects are derived from invertebrate’s ecological traits: feeding types, habitat preferences, longitudinal zonation and locomotion type. Both components are compared and linked to environmental stress, i.e. a gradient of hydromorphological degradation covered by invertebrate sampling sites. The gradient is derived from multiple hydromorphological variables recorded at each site and structured by multivariate analysis.

The results show that specific compositional aspects and the functional diversity are highly correlated, whereas both seem to fail to indicate hydromorphological stress. The latter might show that functional diversity is sustained even in hydromorphologically degraded rivers and, thus, resilient to environmental stress. But do functions and processes continue to work?
[1] Rationalising Biodiversity Conservation in Dynamic Ecosystems (www.rubicode.net). Funded under the European Commission, 6^th FP, Contract No: 036890.