Rediscovery of Brasenia schreberi from soil seed bank in Lake Izunuma-Uchinuma, Japan

Abstract

Seedling emergence method was conducted on the sediments of Lake Izunuma-Uchinuma, Japan. As a result, Brasenia schreberi was rediscovered in the lake for the first time in 20 years. B. schreberi had been commonly distributed in Izunuma-Uchinuma until the 1960's. However, B. schreberi became extinct due to eutrophication and overexploitation. Considering the waters currently high COD concentration (8-10 mg/mL) and that most of the water surface is covered by lotus (Nelumbo nucifera), restoration of the rediscovered B. schreberi in the lake will be difficult at this time. The water quality gap between 1960's and now is a large problem for the restoration of the B. schreberi. Therefore, it may be a realistic to carry out the restoration of B. schreberi only in small and manageable areas around the lake.