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Ecology

It is a core concept of the Water Framework Directive (WFD) that the condition of biological communities is used to assess the ecological quality of surface waters. It has therefore been necessary for SEPA to develop ecological classification systems based on biological communities' robust responses to environmental pressures.

In relation to the WFD, SEPA's ecology function:

• co-ordinates, reviews and supports the development of ecological methods for the implementation of the directive
• provides expert scientific advice, information and interpretation on ecological issues related to new duties
• contributes to the development and management of an adequate and appropriate monitoring network
• participates in and contributes to various UK and European initiatives, such as intercalibration
• coordinates the provision and interpretation of ecological data for water body characterisation and risk assessment

The ecological classification system required under the WFD describes hydromorphological elements as 'supporting the biological elements'. This means SEPA monitors and assesses pressures/impacts on:

• hydrological regime (quantity and dynamics of flow, connection to groundwater);
  
  
• continuity (ability of sediment and migratory species to pass freely up/down rivers and laterally with the floodplain);
  
  
• morphology (ie physical habitat – compositions of substrate, width/depth variation, structure of bed, banks and riparian zone).

Each of the four surface water categories is ascribed specific hydromorphological quality elements (see below).

The text of the WFD calls for hydromorphological elements to contribute to status classification for high status water bodies only. This does not mean that hydromorphology is not important in influencing the condition of water bodies in the other status classes. For good and moderate status the directive calls for the hydromorphological conditions to be 'consistent with the achievement of the values specified…for the biological quality elements'.

In time, this consistency will be determined using the biological classification tools. These tools are currently only sensitive to severe hydromorphological pressures, so SEPA will use hydromorphology to classify into all five status classes until greater sensitivity is achieved.    

• Rivers - depth and width variation; structure and substrate of the river bed; structure of the riparian zone; river continuity.
  
  
• Lochs/lakes - depth variation; quantity, structure and substrate of the bed; structure of the loch/lake shore.
  
  
• Transitional waters (estuaries) - depth variation; quantity, structure and substrate of the bed; structure of the intertidal zone.
  
  
• Coastal waters - depth variation; structure and substrate of the coastal bed; structure of the intertidal zone.

Why?

Surface water morphology is important for:

• defining water bodies at high status;
  
  
• investigating possible reasons for water bodies that fail to reach good ecological status;
  
  
• characterising and setting in place appropriate monitoring of heavily modified and artificial water bodies.

Heavily modified water bodies

Heavily Modified Water Bodies (HMWB) are defined according to two key criteria. First, they must have been substantially changed in character as a result of significant physical alterations by human activity. Second, the alterations must still be providing socio-economic benefits that it would be too expensive and/or technically infeasible to provide in any other fashion. If met, these conditions mean that it is not possible for the water body to meet good ecological status.

'Human activities' are defined as navigation (port facilities or recreation), activities for the purposes of which water is stored in reservoirs (such as drinking-water supply, power generation or irrigation), water regulation, flood protection and land drainage.

Artificial water bodies

An Artificial Water Body (AWB) is a surface water body that has been created in a location where no water body previously existed (eg a canal) and that has not been created by the direct physical alteration or movement of an existing water body. This does not mean that there was only dry land present before. There may have been minor ponds, tributaries or ditches, which were not regarded as a discrete and significant element of surface water and therefore not identified as a water body.

Good ecological potential

Instead of good ecological status, the environmental objective for HMWB/AWB is good ecological potential, which has to be achieved by 2015. The designation is not an opportunity to avoid achieving demanding ecological and chemical objectives, since good ecological potential is an ecological objective which may often, in itself, be challenging to achieve.

EU and UK work

Ecology involvement in the implementation of the WFD on a UK national scale is managed through the UK Technical Advisory Group (UKTAG) Rivers and Lakes Task Teams. These groups are responsible for delivering a series of outputs across the UK required to support implementation of the WFD.

Further information on SEPA's ecology function can be found in the Scotland's environment section.