Site Condition Monitoring of river habitats, 2013: River Tweed LEAFPACS vegetation data

LEAFPACS analysis showed that the Teviot, Ettrick and Yarrow were generally at High or Good status throughout and certainly at the ECS (Evaluated Corridor Section) scale. The upper to middle reaches of the Tweed mainstem and Whiteadder also were of High-Good quality but the middle and lower reaches of these rivers and the Blackadder were mostly of only Moderate status.
Due to prolonged low flow conditions in 2013 filamentous algal growth may have been greater than normal. This affects classifications quite significantly, often lowering the status of a site by one class. The same effect applies at the ECS scale. A total of 25 sites out of 80 surveyed were classified at Moderate or (rarely) Poor status, mainly due to high algal cover.If the Algal metric used in the LEAFPACS classification is excluded from the analysis, the classification then relies only on the RMNI metric and the number of taxa or functional groups recorded. Under this scenario, all ECSs were classed at Good or High status and only 5 out of the 80 survey sites were classified below Good status. These 5 sites were distributed widely across the Tweed mainstem, Teviot and Blackadder.
The 2004 and 1981 survey data were integrated and compared against the 2013 data for the closest equivalent sites. Based on a subset of 21 sites on the Tweed mainstem (surveyed on all three occasions), there is no clear evidence that the Tweed itself has become significantly better or worse in terms of quality over the 32-year period.