Using fossil midges from Saltspring Island, British Columbia to infer changes in temperature over the last 14,000 years

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dc.contributor.authorLemmen, Jillian
dc.contributor.supervisorLacourse, Terri
dc.date.accessioned2016-09-09T18:05:45Z
dc.date.copyright2016en_US
dc.date.issued2016-09-09
dc.degree.departmentDepartment of Biologyen_US
dc.degree.levelMaster of Science M.Sc.en_US
dc.description.abstractFossil midge remains from a sediment core from Lake Stowell, Saltspring Island (48°46’54”N, 123°26’38”W) were used to produce quantitative estimates of mean July air temperature over the last 14,000 years. Chironomid and Chaoborus remains were identified, and multiple models of past temperatures based on transfer functions of northern North American calibration datasets were evaluated. The selected model was used to create the first quantitative paleotemperature estimates for the Gulf Islands region. Inferred paleotemperatures at Lake Stowell varied between 12.1 °C and 18.6 °C over the last 14,000 calendar years. Several major climate phases were identified based on changes in paleotemperature. The base of the record is characterised by a cool lateglacial interval with a minimum inferred July temperature of 12.1 °C. Inferred temperatures generally increased by ~4 °C between ~14,200 and 10,300 cal yr BP but this warming was interrupted by cooling, coincident with the Younger Dryas Chronozone, when inferred temperatures drop ~2 °C from the temperatures immediately preceding this interval. A warm early Holocene extends from ~10,300 to 8100 cal yr BP with temperatures regularly exceeding 16 °C. Following the early Holocene, inferred temperatures decreased to approximately 14.9 °C in the mid-Holocene. After a brief warm peak in the late Holocene, inferred temperatures cooled towards the present. Inferred changes in paleotemperature from Lake Stowell are consistent with other paleoenvironmental studies conducted in southern British Columbia and throughout much of the Northern Hemisphere. Temperature changes at Lake Stowell are muted in comparison to continental sites, which may be due to the influence of marine conditions. This research provides context for other studies in the region, and contributes to our understanding of environmental change since the last glacial maximum.en_US
dc.description.proquestcode0426en_US
dc.description.proquestcode0793en_US
dc.description.proquestcode0353en_US
dc.description.proquestemailjillian.lemmen@gmail.comen_US
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/7531
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectChironomidsen_US
dc.subjectFossil midgesen_US
dc.subjectSaltspring Islanden_US
dc.subjectGulf Islandsen_US
dc.subjectPaleoecologyen_US
dc.subjectPaleolimnologyen_US
dc.subjectPaleotemperatureen_US
dc.subjectBritish Columbiaen_US
dc.subjectPacific Northwesten_US
dc.subjectTemperature reconstructionen_US
dc.subjectModern analogueen_US
dc.titleUsing fossil midges from Saltspring Island, British Columbia to infer changes in temperature over the last 14,000 yearsen_US
dc.typeThesisen_US

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