A Paleolimnological and Modeling Investigation of Water Quality and Biological Changes in Algonquin Park Lakes in Response to Multiple Stressors

Abstract

Algonquin Park (herein called the “Park”) is one of only two parks in Ontario that allows private cottages, with the first leases offered in 1905. In total, 22 lakes in the Park have a total of 303 cottage lots in their catchments, with 326 cottages holding commercial leases. In addition to the cottages, the Park has 12 campgrounds that are accessible by car, with over 1200 campsites. With the recent decision to extend leases until December 31st 2038, the provincial government is gathering information to determine if water quality has been adversely affected by current shoreline development. Furthermore, long-term data on cumulative impacts from multiple stressors are scarce in the Park, and so paleolimnological data and modeling are used here to provide information on: 1) how these lakes have changed since pre-industrial times, relative to a set of reference lakes; and 2) the sensitivity of the lakes to increased nutrient loading. This thesis has two separate but related research chapters. The first chapter focuses on diatom assemblages preserved in the modern (surface) and pre-industrial (bottom) sediment intervals of the 53 study lakes (i.e. 22 lakes that support shoreline cottages, and 31 lakes that are used as reference sites) to help determine whether the present-day limnological conditions differ from pre-industrial conditions, and if so, to examine the nature and magnitude of these diatom changes. This study tracks increases in the relative abundance of Asterionella formosa and Discostella diatom taxa since pre-industrial (ca. A.D. 1850) times in both cottage and reference lakes in Algonquin Park, that are likely due to climatically-induced limnological changes associated with longer ice-free periods and/or longer periods of thermal stratification. No clear signal linked to the cottages could be determined. The second chapter uses the Lakeshore Capacity Model (LCM), developed by the Ontario Ministry of the Environment and Climate Change, to calculate total phosphorus (TP) budgets for the 53 Algonquin Park study lakes, and assesses the relative sensitivity of these lakes to increased phosphorus loading. When applied to the study lakes, the LCM suggests that current TP concentrations in the lakes are below the Provincial Water Quality Objective (PWQO) for TP for lakes within the Precambrian Shield, with the majority of lakes showing low to moderate sensitivity to TP loading. Collectively, my studies show that cottages do not appear to have significantly altered the lakes in Algonquin Park; however, with the prevalence of multiple environmental stressors in a warming climate, a precautionary approach should be taken when considering the management of these lakes.