Trophic Status of Experimental Cutaway Peatland Lakes in Ireland and Implications for Future Lake Creation

Abstract

Of the 80,000 hectares of Bord na Móna owned peatland coming out of industrial production in Ireland approximately the next 25 years, over 20,000 hectares has been designated for shallow lake creation. Four experimental lakes created by flooding areas of redundant cutaway peatland in Co. Offaly were monitored over a 3-year period in order to obtain baseline information on their water quality and trophic status. Results indicate that water chemistry in the constructed lakes was predominantly influenced by the depth and type of the residual peat layers at the sites, the degree of exposure of underlying inorganic subsoils and the type of hydrological regime. Nutrient status was strongly governed by catchment land-uses. Lack of recolonising vegetation at recently abandoned cutaway peatland sites made some new lakes particularly vulnerable to nutrient runoff and algal bloom development. Biologically, the embryonic lakes were characterised by rudimentary food chains, in which higher trophic levels were absent and where the microbiota played an elevated role.