Novel method sheds light on fish death in acidified lakes
Have you ever wondered about how fish life has disappeared from acidified regions? Researchers in Sweden have devised a method to reveal when and how these marine creatures disappeared from acidified lakes. The findings of the study will increase our understanding about the restoration of lakes in acidified regions. Researchers at the University of Gothenburg say the microscopic remains of dead phantom midge larvae (Chaoborus spp.) could shed light on the living conditions of fish, fish death and acidification in lakes across Sweden. The team used sediments found at the bottom of lakes in their study. 'It is actually just like a journey through time,' explains Fredrik Palm, a doctoral student from the Department of Zoology at the University of Gothenburg. '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.' Sources say that soil and water acidification weighs heavily on the minds of environmentalists. Recent studies have shown how a large proportion of Swedish lakes are impacted by acidification. Because of this, biodiversity is taking a huge hit and increasing numbers of fish are dying. According to field experts, there is a clear correlation between fish death and the presence of Chaoborus larvae in lakes. The Gothenburg team believes that researchers can use mandibles from Chaoborus larvae preserved in lake-bottom sediments to identify fish death and other fish changes in lakes that are heavily affected by acidification. This latest tool gives researchers a major boost, particularly because it was the first time that samples had ever been collected, and no historical data on the changes that have affected the fish community were available. The team says it also gives researchers the opportunity to determine the age of sediment samples and the time when changes emerged. 'By analysing Chaoborus mandibles that we recover in the bottom sediments we can tell how different fish communities have changed,' Mr Palm says. 'Not only can we infer whether fish [have] disappeared, we can also see how different fish species have been affected. Roach, for example, are more sensitive to acidification than perch, and we have been able to show whether lakes historically have contained cyprinid fish or not. Remains of acid sensitive zooplankton can simultaneously be used to show trends of progressive acidification in lakes.' This method provides insight into the changes of the fish community in a lake over the last few centuries. Information about how to restore the biology of an acidified lake can also be determined using the same method. According to the researchers, the historical perspective offered by the method could offer analyses of natural variations in lake ecosystems. Mr Palm and colleagues made assessments in the counties of Västra Götaland and Bohuslän, Sweden. Particular attention was placed primarily on the Lake Gårdssjön area in Ucklum, which has been a centre of acidification research in the Nordic state for many decades.For more information, please visit: University of Gothenburg:http://www.gu.se/english
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Sweden