Lake sediments and legacy environmental stressors

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My research program will use aquatic sediments and other key watershed measures to study how lakes respond to environmental change over time. Legacy pollution from human activities in Canada has resulted in damage to many freshwater ecosystems, including their food webs. Although signs of ecosystem recovery are observed, many lakes now experience multiple, co-occurring environmental stressors because of human activities. A long-term time perspective is often needed to understand environmental change because it tends to occur incrementally over many decades. Lake recovery from two well-documented examples of pollution in the Maritime provinces of Canada, insecticides used in forestry and contaminants from gold mining, will be the focus of my research program over the next five years. These examples of widespread chemical and metal(loid) pollution have relevance to other regions of Canada where similar activities occurred in the past. Understanding sediment-bound pollution impacts and how lake recovery occurs are important to assessing aquatic health, recognizing risk, and developing remediation plans for polluted ecosystems. We will use invertebrates and geochemical signatures preserved in dated sediment cores to investigate pollution trends and how contemporary stressors, such as climate change and land use, may influence the ecological recovery of lakes across the 20th century to the present. Methods common to geoscience and aquatic science will be applied to determine the timings of environmental changes, and their impacts relative to "baseline" or typical aquatic conditions. Our approach provides new knowledge on how temperate lake ecosystems may recover from severe pollution while also facing modern environmental stressors.