Euro-limpacs Deliverables


Database for reference conditions - table structure and provisional list of sites

The establishment of the EU Water Framework Directive has required targets for ecological restoration for aquatic ecosystems to be defined explicitly in relation to reference conditions, using the concept of a return to “good ecological status” determined with respect to ecosystems experiencing minimal human impact. There are several methods that allow such reference conditions to be assessed, all of which are being explored in Euro−limpacs. These include:
i) Palaeolimnology using transfer functions and analogue matching techniques. This is a powerful approach, but only appropriate for lakes,
ii) Documentary records/old specimens. This includes both written records and archive material of plant and animal collections from specific sites,
iii) Observational/instrumental records. Very rarely are instrumental records of sufficient length or quality to be useful, but there are some sites within Europe, especially linked to the setting up of freshwater biology institutes in the early twentieth century where very long records can be obtained,
iv) Space for time substitution. This is the most used approach where minimally impacted sites are used to define the ecological characteristics of polluted/disturbed sites of equivalent stream or lake type. This is a key method that can be potentially used for all systems, but assumes that reference sites are indeed minimally impacted, and are of equivalent type,
v) Modelling. Steady state and dynamic models can often be used to define the chemical status of a stream or lake, and such models have been especially well developed for acidification problems. Models nevertheless need careful calibration and verification,
vi) Expert opinion. In the absence of alternatives, experienced scientists can often provide opinions on reference states for streams and lakes.
In WP8 we will attempt to evaluate these different approaches for lakes and streams using data from specific sites where some or all of these methods can be used. The first step is to set up a metadatabase of sites of different types across Europe where the required information is available. So far we have defined the variables that need to be included in the meta−database and have designed a meta−database structure specifically for palaeolimnological data.

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