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Long-Term Changes of Hypolimnetic Dissolved Oxygen and Phytoplankton Community Composition in a Large Lake, Lake Simcoe, Ontario and Revisit Dissolved Oxygen Profile Models for Lakes in Central Ontario

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dc.contributor.advisorMolot, Lewis
dc.creatorLi, Jiahua
dc.date.accessioned2016-11-25T14:06:25Z
dc.date.available2016-11-25T14:06:25Z
dc.date.copyright2016-06-13
dc.date.issued2016-11-25
dc.date.updated2016-11-25T14:06:25Z
dc.degree.disciplineBiology
dc.degree.levelMaster's
dc.degree.nameMSc - Master of Science
dc.description.abstractLong-term changes in volume-weighted hypolimnetic dissolved oxygen (VWHDO) and phytoplankton community composition were examined as important water quality indicator in Lake Simcoe, a large freshwater lake with impacts by various drivers such as dreissenid mussel (DM) invasion, reduction in phosphorus (P) loading and climatic change and oscillations. VWHDO dynamics were examined by several multiple linear regressions which revealed that VWHDOmin was positively correlated with the invasion of DM and negatively correlated with hypolimnetic water temperature; VWHDO depletion rate (DR) was positively correlated with ammonia and total phosphorus (TP) annual loading. Hence, longer period of thermal stratification (L) may have offset improvements in VWHDOmin generated by P controls and invasive species. Redundancy analysis and variation partitioning revealed that DM acted on phytoplankton composition indirectly by changing the environmental conditions because environmental variables and DM individually explained little variance in phytoplankton composition but water chemistry variables and DM collectively explained a large portion of the variation. A series of models predicting the uppermost plane of the DO-depleted zone (Zox), spring dissolved oxygen (DOi) profile and end-of-summer dissolved oxygen (DOf) profile built by Molot et al. (1992) were re-analyzed, re-calibrated with more recent data (A lakes during 1990-2013), and validated (B lakes during 1990-2013). With the current brownification trend (increased DOC), we expected to see increased DOf at all depths; however, increased reduced N species (ammonia) in the hypolimnion would offset the brownification effect.
dc.identifier.urihttp://hdl.handle.net/10315/32714
dc.language.isoen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectLimnology
dc.subject.keywordsClimate change
dc.subject.keywordsPhosphorus reduction
dc.subject.keywordsDreissenid mussels
dc.subject.keywordsOxygen depletion
dc.subject.keywordsMultiple stressors
dc.subject.keywordsPhytoplankton composition
dc.subject.keywordsLarge-scale climatic cycles
dc.subject.keywordsLake Simcoe
dc.titleLong-Term Changes of Hypolimnetic Dissolved Oxygen and Phytoplankton Community Composition in a Large Lake, Lake Simcoe, Ontario and Revisit Dissolved Oxygen Profile Models for Lakes in Central Ontario
dc.typeElectronic Thesis or Dissertation

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