Grant: Discovery Grants Program - Individual

The boreal biome in Alberta is a vast, ecologically diverse region spanning the northern part of the province. Three percent of the region comprises lakes that support abundant aquatic life. These lakes are of great importance to the economic and cultural well-being of the people living there. Many lakes in the region face environmental challenges related to high levels of nutrient enrichment (eutrophication) from agriculture, industry, and/or municipalities, as well as the effects of a variable and rapidly changing climate. Fully understanding the degree to which lake eutrophication is driven by climate change is hampered by the short instrumental climatological record. The impact of multiple environmental stressors further complicates paleoenvironmental interpretation, thus requiring high-resolution temporal data and multiple diagnostic proxies to identify and distinguish these many drivers. My proposed research, in collaboration with First Nations partners, will address the eutrophication problem through an assessment of diagnostic bioindicators [testate lobose amoebae (TLA)], geochemical markers and sedimentological features, which are often well preserved in lake depositional records. The research will focus on two interlinked objectives: Objective 1: My HQP and I will determine the characteristics and specific mechanisms of TLA (an important intermediary food web component) community change in response to eutrophication. We will develop TLA proxy analysis into a cost-effective methodology for assessing the severity of eutrophication along a gradient of lakes ranging from unimpacted to severely degraded. A major source of nutrients is catchment runoff, and this vector will be assessed through deployment of sediment traps where distinct contributors to runoff (e.g., spring freshet, rainfall events) will be characterized using a novel methodology, End Member Mixing Analysis (EMMA). Objective 2: My HQP and I will assess, using TLA, EMMA and other proxies, how and why lake ecosystems in the region have changed over time. We will use a subset of these lakes to document changes in response to climate and land use change since the mid 19th century. Proxy analysis will be used to assess underlying causes of eutrophication in lakes and to document the history of harmful algal blooms (HABs), an emergent problem in many lake systems. This research will employ an assessment of the occurrence of microcystins, a toxin released by HABs that preserves well in lake sediment records. In collaboration with Indigenous scientists, we will also develop best practice for weaving western science proxy analysis of post 19th century lake records with Indigenous Science to tell the `Story of the Land'. This will provide policy makers and planners with critical information on the progressive consequences of eutrophication, HABs and other stressors on aquatic ecosystems, leading to possible natural and/or engineered remediation solutions.