Beschreibung:
<p>The subfossil bottom sediment of Lake Gårdsjön, an acidified lake in SW Sweden, was examined to see what faunal changes had taken place in connection with acidification. The development of the chironomid population was traced by studying the stratification of larval head capsules in the sediment. Around 1960 the pH-value of the lake started to drop significantly. Head capsule analysis showed that this coincided with an increased abundance of Sergentia, Psectrocladius and Protanypus, while no head capsules at all of Dicrotendipes and Microtendipes were found after 1960. This development was not wholly reflected in the recent chironomid composition in the lake, as Dicrotendipes together with Chironomus anthracinus were the most abundant recent chironomids. However, as a whole the results agree with those obtained in other studies of the benthos of acidified lakes. Probable causes for the changes of the chironomid fauna are discussed.</p>