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Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation

Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation
Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation
We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from HatWeld Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and Xuctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in Wsh and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between diVerent insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems
fossil insects, coleoptera, chironomidae, ecosystem processes, wetland dynamics · Mire ontogeny · Shallow lakes · Palaeolimnology · Restoration
2055-2078
Whitehouse, Nicki J.
d288a39c-d57e-4852-b794-a8a3d7a2c403
Langdon, Peter G.
95b97671-f9fe-4884-aca6-9aa3cd1a6d7f
Bustin, Richard
1e07fd3f-30c0-4f89-859e-626cd48f7896
Galsworthy, Sarah
538d7416-033e-4f2e-8a14-8ce3a4cda689
Whitehouse, Nicki J.
d288a39c-d57e-4852-b794-a8a3d7a2c403
Langdon, Peter G.
95b97671-f9fe-4884-aca6-9aa3cd1a6d7f
Bustin, Richard
1e07fd3f-30c0-4f89-859e-626cd48f7896
Galsworthy, Sarah
538d7416-033e-4f2e-8a14-8ce3a4cda689

Whitehouse, Nicki J., Langdon, Peter G., Bustin, Richard and Galsworthy, Sarah (2008) Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation. Biodiversity and Conservation, 17 (9), 2055-2078. (doi:10.1007/s10531-008-9411-7).

Record type: Article

Abstract

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from HatWeld Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and Xuctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in Wsh and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between diVerent insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems

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More information

Published date: August 2008
Keywords: fossil insects, coleoptera, chironomidae, ecosystem processes, wetland dynamics · Mire ontogeny · Shallow lakes · Palaeolimnology · Restoration

Identifiers

Local EPrints ID: 64238
URI: https://eprints.soton.ac.uk/id/eprint/64238
PURE UUID: d109b3e1-494d-4ae7-b2a6-e6f1be0a1d7e
ORCID for Peter G. Langdon: ORCID iD orcid.org/0000-0003-2724-2643

Catalogue record

Date deposited: 17 Dec 2008
Last modified: 17 Sep 2019 01:05

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