Microscopic remains of dead Phantom midge larvae (Chaoborus spp.) may explain a few hundred years of history of the living conditions of fish, acidification and fish death in Swedish lakes. Researchers at the University of Gothenburg, Sweden, have developed a method of using lake-bottom sediments to show when and how fish life disappeared from acidified lakes invaluable knowledge for lake restorations in acidified regions.
"It is actually just like a journey through time. Fish hardly leave any remains of their own when they die, but if we instead study the presence of organisms that are affected by fish, we can find clear traces. By studying mandibles (mouth parts) from Chaoborus larvae in lake sediments, we can recreate the history of the lake back to the early 19th century," says Fredrik Palm of the Department of Zoology at the University of Gothenburg.
Acidification of soil and water is one of the greatest environmental problems of modern times. A large proportion of Swedish lakes show clear signs of acidification, resulting in extensive fish death and severely reduced biodiversity.
Recent research has pointed to a clear correlation between fish death and the presence of Chaoborus larvae in lakes. Mandibles from Chaoborus larvae preserved in lake-bottom sediments can therefore be used to identify fish death and other fish changes in severely acidified lakes.
History in the rear-view mirror
The new method makes it possible to study the effects of acidification in lakes where no samples have previously been collected and where there are no historical data on fish community alterations. As it is also possible to determine the age of sediment samples, this method can additionaly reveal when different changes have occurred.
"By analysing Chaoborus mandibles that we recover in the bottom sediments we can tell how different fish communities have changed. Not only can
|Contact: Fredrik Palm|
University of Gothenburg