Changes in aquatic macrophyte communities in Loch Leven: evidence of recovery from eutrophication?

This paper assesses changes in the macrophyte community of Loch Leven over a period of 100 years. Evidence is presented that shows that these changes are asso¬ci-ated with eutrophication and with subsequent recovery from eutro¬phi¬ca¬tion when anthropogenic nutrient inputs to the loch were reduced. This study uses macrophyte survey data from 1905, 1966, 1972, 1975, 1986, 1993, 1999 and 2008. In each of these surveys, apart from that conducted in 1905, the loch was divided into 19 sectors, each with at least one transect ranging from the shallowest to the deepest occurrence of macrophytes. From these data, a range of indicators of recovery were derived at the whole lake scale: the relative abun¬dance of taxa, taxon richness and evenness, and maximum growing depth. All of these metrics showed an improvement since 1972. Species richness, measured at the scales of survey sector and individual samples, also appeared to have increased in recent years. All of these measures, coupled with ordination of presence/absence composi¬tion data from all survey years, indicate that the macrophyte community in the loch is recovering towards the state that was recorded in 1905.