EcoClassification and EcoStatus

What is EcoClassification?

Ecological classification, or EcoClassification, refers to the determination and categorisation of the Present Ecological State (PES; health or integrity) of individual biophysical attributes of the river that is being assessed, compared to the natural or close to natural reference condition. These biophysical attributes refer to the drivers (e.g. physico-chemical, geomorphology, hydrology) and biological responses (e.g fish, riparian vegetation and aquatic invertebrates) of an aquatic ecosystem.

Purpose of EcoClassification

The main purpose of EcoClassification is to gain insights into the cause and origin of the deviation of the PES of biophysical attributes from the reference condition. This information is required to derive desirable and attainable future ecological objectives for the river such as in ecological reserve and RHP assessments.

Relevance to the RHP

Although river health data is assessed in terms of the severity of ecosystem changes, the RHP primarily focuses on biological responses as indicators of ecosystem health. Only a general assessment of the cause-and-effect relationship between the drivers and the biological responses of a system is hence made. It is within this context then that the EcoClassification is applied in RHP assessments.

What is EcoStatus?

EcoStatus or Ecological Status refers to an integrated ecological category for rivers. In other words, the ecological category derived for each of the biological response components for a particular river is used to derive an overall, integrated ecological state or EcoStatus.

The formal definition for EcoStatus is:

‘The totality of the features and characteristics of the river and its riparian areas that bear upon its ability to support an appropriate natural flora and fauna and its capacity to provide a variety of goods and services'.

EcoStatus Determinations

Indices are determined for each of the biophysical attributes by using a rule-based modeling approach. For the biological responses component of these attributes (applicable to the RHP), the models are referred to as the: Fish Response Assessment Index (FRAI), the Macro-invertebrate Response Assessment Index (MIRAI), the Riparian Vegetation Response Assessment Index (VERAI), etc.

There are 5 levels of EcoStatus determinations (depending on information available), which range from a Desktop level to a Level 4. For RHP purposes, the Level 3 method at least is to be used.

Documentation

Version 1 of the “River EcoClassification Manual for EcoStatus determination is currently available (pdf 0.9Mb). Version 2 of the manual, which will include additional detailed methods, will be available by end March 2007. The development of this manual was jointly funded by the Water Research Commission (WRC) and DWAF.

For more information

Contact Dr Neels Kleynhans (kleynhansn@dwaf.gov.za) or Ms Delana Louw (iwre@icon.co.za).