Use of subfossil Chaoborus mandibles in models for inferring past hypolimnetic oxygen

Assemblages of subfossil Chaoboridae mandibles from 80 thermally-stratified shield lakes in southern central Canada were examined to explore the influence of subfossil Chaoborus on subfossil Chironomidae-based paleolimnological inference models of deepwater oxygen, as volume-weighted hypolimnetic ox...

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Bibliographic Details
Published in:Journal of paleolimnology 2010-06, Vol.44 (1), p.43-50
Main Authors: Quinlan, Roberto, Smol, John P.
Format: Article
Language:English
Subjects:
Chaoboridae
Chaoborus
Chironomus
Climate Change
Earth and Environmental Science
Earth Sciences
Fossils
Freshwater
Freshwater & Marine Ecology
Geology
Original Paper
Oxygen
Paleoecology
Paleontology
Physical Geography
Sedimentology
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Summary:Assemblages of subfossil Chaoboridae mandibles from 80 thermally-stratified shield lakes in southern central Canada were examined to explore the influence of subfossil Chaoborus on subfossil Chironomidae-based paleolimnological inference models of deepwater oxygen, as volume-weighted hypolimnetic oxygen (VWHO). Inclusion of subfossil Chaoborus in subfossil Chironomidae-based VWHO models only improved model performance modestly, however it produced substantively better inferences of hypolimnetic oxygen in anoxic lakes, because Chaoborus had a much stronger positive relationship with low VWHO compared to chironomid taxa indicative of anoxic conditions, such as Chironomus . A Chaoborus mandible:Chironomidae head capsule ratio (chaob:chir) may be a useful index in paleolimnological studies, as chaob:chir in a surface sediment training set was significantly related to VWHO, and displayed little co-variation with other limnological variables such as trophic status (e.g. TP, TN) or lake depth (e.g. Z max ). Chaob:chir values in a stratigraphic analysis tracked chironomid-inferred VWHO, however the use of chaob:chir in regional ‘top–bottom’ paleolimnological studies must be used with caution.
ISSN:0921-2728
1573-0417
DOI:10.1007/s10933-009-9384-x