Changes in fossil chironomid remains along a depth

Authors: Stefan Engels Les C Cwynar

Publish Date: 2011/01/29

Volume: 665, Issue: 1, Pages: 15-38

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Abstract

Many environmental variables that are important for the development of chironomid larvae such as water temperature oxygen availability and food quantity are related to water depth and a statistically strong relationship between chironomid distribution and water depth is therefore expected This study focuses on the distribution of fossil chironomids in seven shallow lakes and one deep lake from the Plymouth Aquifer Massachusetts USA and aims to assess the influence of water depth on chironomid assemblages within a lake Multiple samples were taken per lake in order to study the distribution of fossil chironomid head capsules within a lake Within each lake the chironomid assemblages are diverse and the changes that are seen in the assemblages are strongly related to changes in water depth Several thresholds ie where species turnover abruptly changes are identified in the assemblages and most lakes show abrupt changes at about 1–2 and 5–7 m water depth In the deep lake changes also occur at 96 and 15 m depth The distribution of many individual taxa is significantly correlated to water depth and we show that the identification of different taxa within the genus Tanytarsus is important because different morphotypes show different responses to water depth We conclude that the chironomid fauna is sensitive to changes in lake level indicating that fossil chironomid assemblages can be used as a tool for quantitative reconstruction of lake level changesWe would like to thank Nancy Zhou Sjoerd Bohnke Toine Bostelen Daniel LeBouthillier and Andrew Rees for assistance during fieldwork Andrew Rees also provided invaluable assistance with the PLR analyses and commented on an earlier draft of this manuscript We are thankful for permission to perform fieldwork at Crooked Pond which was granted by Stephanie Koch US Fish and Wildlife Service We’d furthermore like to thank the Hyslop family for permission to work on their property at Bloody Pond Steve Brooks Ann DieffenbacherKrall Donna Francis Oliver Heiri and Ian Walker are thanked for their help with the identification of some of the rare taxa that were encountered during this project Two anonymous reviewers are thanked for their useful feedback and suggestions Funding by the Niels Stensen Foundation for SE is greatly appreciated This research was funded in part by a Discovery Grant to LCC from the Natural Sciences and Engineering Research Council of Canada

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