The uncertainty surrounding the impact of future changes in climate and water resources
has created renewed interest on how lakes have responded to drought in the past. There
is a need to determine potential future available water by understanding past changes in
water levels; the underlying ecological characteristics of using diatoms as a proxy for
lake-level reconstructions is the basis of this thesis. By integrating knowledge from past
water-level fluctuation studies and theories, along with developing a better understanding
of diatom ecology in lake systems, more effective techniques are being developed to
improve water-depth reconstructions. Diatom assemblages were examined from eight
lakes in northwestern Ontario collected in surface sediments along a depth gradient at
~1-m water-depth intervals. Three major zones, based on the composition of diatom
assemblages in each lake were consistently identified in all lakes: i) a near-shore
assemblage of Achnanthes (sensu lato) species and other benthic taxa (Nitzschia,
Cymbella); ii) a mid-depth small Fragilaria (sensu lato)/ small Aulacoseira zone with
various Navicula taxa, and iii) a deep-water planktonic zone. The depths at which
transitions between these zones are located varied among lakes, and the depth of the
transition between the planktonic and benthic zones was consistent with water chemistry
variables (e.g. DOC, TP) that are related to light attenuation. Deeper pelagic to benthic
transitions occurred in lakes with the lowest DOC and TP (i.e. generally more light
attenuation in lakes with higher concentrations of TP or DOC). Other findings included a
decrease in species evenness and numbers with depth, along with an increase in scaled
chrysophyte relative to diatoms. / Thesis (Master, Biology) -- Queen's University, 2010-07-23 12:36:01.347
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/5938 |
| Date | 23 July 2010 |
| Creators | Kingsbury, Melanie V. |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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