Krause-Jensen, D. & Rasmussen, M.B. 2009: Historisk udbredelse af ålegræs i danske kystområder. Danmarks Miljøundersøgelser, Aarhus Universitet. 38 s. – Faglig rapport fra DMU nr. 755.
Historical distribution of eelgrass in Danish coastal waters
This report compiles and analyses historical data on the depth distribution of eelgrass in Denmark that constitutes a reference for evaluating the ecological status of contemporary eelgrass. The compilation of the histo-rical literature provided a large data material on the depth distribution of eelgrass from the 1880’s to the 1970’s – 1429 observations in total, of which we estimate that 335 represent eelgrass depth limits. We divided the data in two parts: before and after the eelgrass wasting disease in the 1930’s, that killed the majority of the Danish eelgrass populations. The early data set is the most extensive and has the largest geographical cover with 306 observations of depth limits distributed across the country during a period with limited nutrient loading and extensive eelgrass meadows. This data set describes a reference situation for 6 of the marine type areas and 66 of the 163 water bodies in Denmark. Data show that the historical eelgrass populations generally grew very deep – typically to an average of 8.5-10.4 meters depth in the open water type areas and to an average of 3.9-10.1 in the estuarine type areas.
Full report (danish only) in PDF format (1,3 MB)
