Flood Movements of the Littoral Fauna of Windermere

WINDERMERE is an oligotrophic lake with typical steep sides and narrow littoral region. At the north-west end the lake is backed by mountains which rise to 830 m. (2700 ft.), forming an extensive watershed with a steep run off. The country south-east of the watershed is drained by two main streams, the Rothay and the Brathay, which unite a quarter of a mile above the lake. Cunsey Beck and Troutbeck, together with a few more small streams, also flow into the lake. The watershed gets rapidly saturated, and the surplus water drains away into the streams which rapidly become flooded and raise the level of the lake. A preliminary account of some characteristic littoral animal communities of Windermere has already appeared (Moon, 1934), and further investigations are in progress. In making these studies certain lines of evidence have suggested that the fauna is constantly moving about the shore. Some of the most striking evidence of these movements is afforded by response to changes in the lake level brought about by floods. Detailed observations have been made on these movements, the results of which are recorded here.