Module 2 survey of freshwater habitats

A sample survey of freshwater biota, water quality and river habitats.

• Click here to access the final report for this module

Streams and rivers are major linear features of the landscape. Watercourses and their banks support a wide diversity of plants and animals and act as a corridor for the movement of both aquatic and terrestrial animals such as fish, birds, otters and other mammals. Broad, well-vegetated bankside strips can also act as a buffer zone reducing the impact of agricultural activity on the biological condition of the stream. Rivers are also important for domestic, agricultural and industrial water supply and for recreational purposes.

Aquatic studies were first incorporated in Countryside Surveys in 1990 when aquatic macro-invertebrate samples were collected. These small animals, which include worms, snails, shrimp, mayflies, caddis flies and other insects, are widely used to assess the biological quality of watercourses. 

Analyses showed that substantial numbers of rivers in the British countryside were not in good biological condition, including many of the small headwater streams that were commonly sampled during the survey. The survey also showed that headwaters supported several taxa of national conservation importance and were a major source of catchment biodiversity.

The 1990 results provided a baseline for assessing future change and the same sites were sampled in the same manner in 1998. In addition, a range of new techniques were introduced in Countryside Survey 2000 in order to give a broader view of the biological condition of streams and the habitat quality of their river corridors. 

The new techniques employed in CS2000 are: 

• River Habitat Survey (RHS)

• Trophic Diatom Index (TDI)

• Mean Trophic Ranking of aquatic macrophyte assemblages (MTR)

• Collection of aquatic mosses

• Chironomid Pupal Exuviae Technique using cast skins of emerging midges (CPET) 

The most important of these is River Habitat Survey, which is used for assessing the physical character and quality of river habitats and for providing the information needed to sustain and enhance biodiversity in the river corridor. In CS2000, RHS provided a link between the land cover studies of CEH and surveys of the streams’ flora and fauna.