John P Smol

• OC, OOntBSc, MSc, PhD, LLD (hc), PhD (hc), DSc (hc), FRSC, FRS
• Chair at Queen's University

Diatom-based paleolimnological studies conducted ~25 years ago on five lakes (i.e., Big Rideau, Upper Rideau, Lower Rideau, Indian and Otter lakes) within the Rideau Canal system (Ontario, Canada) tracked extensive catchment disturbances related to canal construction (starting ca. 1828). Over the past three decades, these lakes have experienced add...

Understanding how species adapt to environmental change is necessary to protect biodiversity and ecosystem services. Growing evidence suggests species can adapt rapidly to novel selection pressures like predation from invasive species, but the repeatability and predictability of selection remain poorly understood in wild populations. We tested how...

Big Meadow Bog, in the center of Brier Island, Nova Scotia, has long been the nesting site for American herring gulls (Larus smithsoniansus Coues), with recent counts of approximately 3000 pairs of birds at the colony in the summer. Gulls move from the colony to fish-processing plants, mink farms, aquaculture sites, and marine coastlines to feed, a...

In keeping with the tradition of past awardees of the International Paleolimnology Association Rick Battarbee Lifetime Achievement Award, I provide this career retrospective to acknowledge the outstanding students and other collaborators I have enjoyed working with and to reflect on some of the lessons I learned over the last four decades. Whilst s...

The impacts of permafrost thaw do not manifest uniformly across the Arctic, and this presents challenges for predicting how permafrost‐affected lakes will respond to climate change. Here, we leveraged long‐term field data collection and studies of a particular permafrost lake type (predisposed to thaw slump disturbance) in the Tuktoyaktuk Coastland...

Body size may potentially be a key characteristic for both an individual and a community response to environmental change that palaeolimnological studies can document. Most palaeoecological investigations are based on the reconstruction of past changes in species assemblages, although some studies have incorporated body size as an indicator of pa...

Owing to its specialised methodology, palaeoecology is often regarded as a separate field from ecology, even though it is essential for understanding long-term ecological processes that have shaped the ecosystems that ecologists study and manage. Despite advances in ecological modelling, sample dating, and proxy-based reconstructions facilitating d...

Seabird colonies with long-term monitoring records, i.e., > 50 years, are rare. The population data for northern gannets (Morus bassanus) in Cape St. Mary’s (CSM) Ecological Reserve (Newfoundland and Labrador, Canada) is robust, extending back to 1883 when the colony was presumed established. We inferred the colony’s historical population shifts by...

Known as the “Holocene temperature conundrum”, controversy remains between paleoclimate reconstructions indicating cooling during the late-Holocene versus model simulations indicating warming. Here, we present a composite Holocene winter temperature index record derived from East Asian winter monsoon (EAWM) reconstructions. This new temperature ind...

Arctic freshwater ecosystems are on the “frontline” of climate change, but due to a lack of direct long‐term monitoring data, indirect approaches, such as algal‐based paleolimnology, must be used to reconstruct past limnological conditions. Our understanding of the responses of small‐ to mid‐sized Arctic lakes to climate warming has increased over...

The lead‑zinc smelter at Trail (British Columbia, Canada) has operated continuously for ∼125 years, with long-standing concerns that transboundary metal(loid) and sulphur emissions have contaminated water bodies in both western Canada and Washington (WA), USA. To assess aquatic ecosystems affected by over a century of industrial contamination requi...

Seabirds are biovectors that transport large concentrations of nutrients from their marine feeding areas to terrestrial breeding grounds. Here, we used subfossil cladoceran assemblages to assess if, and how, changes in the world’s largest colony of Leach’s Storm-Petrels affected the structure of Cladocera assemblages over the past ∼1700 years. Usin...

Archaeological studies of pre-historic Arctic cultures are often limited to artefacts and architecture; such records may be incomplete and often do not provide a continuous record of past occupation. Here, we used lake sediment archives to supplement archaeological evidence to explore the history of Thule and Dorset populations on Somerset Island,...

Urban and peri-urban lakes experience a wider array of environmental stressors, and often at a higher intensity, than their rural counterparts, including road salt runoff. A paleolimnological approach was used to determine pre-disturbance limnological conditions and to evaluate the impact of environmental stressors (nutrient inputs, climate change,...

Diatoms are key components of freshwater ecosystems and are regularly used for paleolimnological reconstructions, in which defining species optima and tolerances is fundamental for interpreting assemblage shifts in a sediment record. Here, we examined responses of diatoms across three major environmental gradients—dissolved inorganic carbon (range:...

For over a century, the copper and nickel mining centre of Sudbury in northeastern Ontario (Canada) was a major source of sulphur dioxide and other pollutants, degrading terrestrial and aquatic ecosystems in the surrounding region. In the 1970s, emissions were drastically reduced due to concerns over widespread environmental damage. Killarney Provi...

Mining in northern Canada has been known to cause major environmental problems; however, historical monitoring data are scarce or non-existent. Here, we use a multi-proxy (metals, bioindicators, pigments) paleolimnological approach to track the impacts of mining activity near Keno City, on the traditional land of the First Nation of Na-Cho Nyäk Dun...

The Rideau Canal (Ontario, Canada) was constructed in the early 1830s, primarily as a means to transport military personnel, but now is primarily recreational. The construction of the canal and associated flooding, as well as other land-use changes, likely impacted lakes within the system, however, long-term monitoring data are not available. Furth...

Historical gold mining operations between the 1860s and 1940s have left substantial quantities of arsenic- and mercury-rich tailings near abandoned mines in remote and urban areas of Nova Scotia, Canada. Large amounts of materials from the tailings have entered the surface waters of downstream aquatic ecosystems at concentrations that present a ris...

Algal bioindicators, such as diatoms, often show subdued responses to eutrophication in Arctic lakes because climate‐related changes (e.g., ice cover) tend to be the overriding factors influencing assemblage composition. Here, we examined how sub‐Arctic ponds historically receiving high nutrient inputs from nesting seabirds have responded to recent...

Lake sediments consist of organic and inorganic matter originating from autochthonous (in-lake) and allochthonous (from the catchment and beyond) sources. Thus far, paleolimnological studies of biological communities have focussed primarily on morphological subfossils preserved in sediments, and as such most analyses are based on a relatively limit...

This book, entitled Tracking Environmental Change Using Lake Sediments: Volume 6 – Sedimentary DNA, provides an overview of the applications of sedimentary DNA-based approaches to paleolimnological studies. These approaches have shown considerable potential in providing information about the long-term changes of overall biodiversity in lakes and th...

Atmospheric acid deposition disrupted terrestrial-aquatic carbon cycling by drastically lowering dissolved organic carbon (DOC) loads in many lakes across NE North America and northern Europe during the 20th century. However, little is known about how acid deposition has altered the role of lakes as long-term carbon sinks. We present contemporary (...

Due to a specialised methodology, palaeoecology is often regarded as a separate field from ecology even though it is essential to understand long-term ecological processes that have shaped ecosystems that ecologists study and manage. Even though advances in ecological modelling, sample dating, and proxy-based reconstructions have enabled direct com...

North temperate and boreal lakes are affected by a complex suite of anthropogenic stressors, yet little is known about how these ecosystems are faring across the most lake‐rich nation, Canada. The NSERC Canadian Lake Pulse Network is the first large‐scale national survey of its kind, with the aim of assessing the health of Canadian lakes, determine...

There is a scarcity of long-term chemical monitoring data for lakes in Algonquin Provincial Park (APP), with minimal understanding of the impacts of cottage-leases (e.g., cottage lots, campgrounds, and commercial leases) on lake water chemistry. We examine spatial patterns in water chemistry and landscape features of 32 reference and 22 cottage-lea...

Mining in Northern Canada has been known to cause major environmental repercussions; however, monitoring data are scarce or non-existent. Here, we use a multi-proxy (metals, bioindicators, pigments) paleolimnological approach to track the impacts of mining activity near Keno City, on the traditional land of the First Nation of Na-Cho Nyäk Dun, in c...

Freshwater ecosystems face numerous threats, including habitat alteration, invasive species, pollution, over extraction of resources, fragmentation, and climate change. When these threats intensify and/or combine with each other, their impacts can shift the ecosystem past a tipping point, producing a major and potentially irreversible shift in stat...

Ecosystems experiencing pressures are at risk of rapidly transitioning (“tipping”) from one state to another. Identifying and managing these so-called tipping points continue to be a challenge in marine, freshwater, and terrestrial ecosystems, particularly when multiple potentially interacting drivers are present. Knowledge of tipping points, the m...

Historically, many high‐elevation lakes in the tropical Andes have been observed to mix frequently, with rare, brief periods of thermal stratification. As temperatures have risen in the Andes over the past several decades, thermistor data have shown that many lakes are now experiencing longer periods of thermal stratification with resultant ecologi...

Cache Lake, an ultra-oligotrophic Precambrian Shield lake located in Algonquin Provincial Park (Ontario, Canada), was manipulated in the summers of 1946 and 1947 when approximately 9.4 tons (cumulatively) of 12–24–12 (nitrogen-phosphorus-potassium) fertilizer was added to promote plankton growth and the possible enhancement of fish populations. Lit...

Great Slave Lake (GSL), one of the world's largest and deepest lakes, has undergone an aquatic ecosystem transformation in response to twenty-first-century accelerated Arctic warming that is unparalleled in at least the past two centuries. Algal remains from four high-resolution palaeolimnological records retrieved from the West Basin provide basel...

Base metal smelting in Sudbury (Ontario, Canada) resulted in marked environmental degradation starting in the late nineteenth century. The environmental legacy of intensive industrial activity remains evident in the region despite remediation efforts and recovery. Even though chironomids (Diptera: Chironomidae) are important trophic intermediates,...

The Changbaishan Millennium eruption (946–947 CE) was one of the strongest volcanic activities over the past 2000 years, which greatly influenced the nearby wetland ecosystems. However, the carbon accumulation dy- namics and development processes of these peatlands have rarely been investigated. This study tried to reveal the carbon accumulation dy...

Eutrophication, which remains one of the greatest threats to water quality worldwide, is particularly acute in agricultural areas. Here we assessed long-term drivers of potential pollution inputs to lakes in southwest Nova Scotia (Canada), a region marked by fur farming (mainly mink) and other agricultural activities. We used a BACI (before-after-c...

Cyanobacterial blooms pose a significant threat to water security, with anthropogenic forcing being implicated as a key driver behind the recent upsurge and global expansion of cyanobacteria in modern times. The potential effects of land-use alterations and climate change can lead to complicated, less-predictable scenarios in cyanobacterial managem...

Diatoms are powerful biomonitoring indicators for contemporary and past limnological conditions, provided that their environmental optima are well-defined. Surface-sediment-calibration (or training) sets are widely used to develop quantitative transfer functions linking species distributions to limnological variables. Accurate estimates of each tax...

The global rise of cyanobacterial blooms emphasizes the need to develop tools to manage water bodies prone to cyanobacterial dominance. Reconstructing cyanobacterial baselines and identifying environmental drivers that favour cyanobacterial dominance are important to guide management decisions. Conventional techniques for estimating cyanobacteria i...

Cache Lake, an ultra-oligotrophic Precambrian Shield lake located in Algonquin Provincial Park (Ontario, Canada), was manipulated in the summers of 1946 and 1947 when approximately 9.4 tons (cumulatively) of 12-24-12 (nitrogen-phosphorus-potassium) fertilizer was added to promote plankton growth and the possible enhancement of fish populations. Lit...

Covering 55% of Canada’s total surface area and stretching from coast to coast to coast, the Canadian boreal zone is crucial to the nation’s economic and ecological integrity. Although often viewed as relatively underdeveloped, it is vulnerable to numerous stressors such as mining, forestry, and anthropogenic climate change. Natural archives preser...

Understanding how animals respond to large-scale environmental changes is difficult to achieve because monitoring data are rarely available for more than the past few decades, if at all. Here, we demonstrate how a variety of palaeoecological proxies (e.g. isotopes, geochemistry and DNA) from an Andean Condor (Vultur gryphus) guano deposit from Arge...

Smelting activities have strongly affected the Sudbury (Ontario, Canada) region since the late-nineteenth century, leading to acidification and metal contamination of local ecosystems. Regulations restricting acid deposition were enacted in the 1970s, after which many lakes exhibited increasing pH and decreasing metal concentrations. Given the docu...

underwater light availability and exposure of ultraviolet radiation (UV) in mountain lakes is mainly controlled by dissolved organic matter and ice-cover. However, both of these factors are affected by climate warming and other anthropogenic pressures. Still, little is known of the impacts of long-term fluctuations in underwater light conditions on...

Documenting spatiotemporal patterns of the Holocene Optimum (HO) at the climatically sensitive East Asian monsoon (EAM) margin are essential for understanding monsoon climate dynamics. However, the timing of the onset of the HO at the EAM margin is still debated and progress has been partly hindered by age uncertainties in different proxy records....

Ruth-Roy Lake (Killarney Provincial Park, Ontario, Canada) is an ultra-oligotrophic, naturally acidic waterbody. Lakes in Killarney Provincial Park were impacted by long-range transportation of contaminants from copper–nickel smelting operations in nearby Sudbury, but recent lake monitoring indicates that Ruth-Roy Lake has been less acidic than inf...

Acidification and eutrophication are common limnological stressors impacting many water bodies across the globe. While the negative impacts of these stressors on limnetic communities are generally known, their influence on the accumulation of specific sediment constituents, such as metals, remains unclear. Benefitting from past research and long-te...

Holocene evolution of the East Asian summer monsoon (EASM), which provides precipitation to 1.6 billion people and has played a key role in the development of Chinese civilizations, has been hypothesized to be driven directly by summer insolation changes. However, an insolation-driven early-Holocene EASM maximum has not been convincingly validated,...

Northern peatlands represent one of the largest biospheric carbon reservoirs in the world. Their southern margins act as new carbon reservoirs, which can greatly influence the global carbon dynamics. However, the Holocene initiation, expansion and climate sensitivity of these peatlands remain intensely debated. Here we used a compilation of basal p...

Algal communities act as sensitive indicators of past and present climate effects on northern lakes, but their responses can vary considerably between ecosystems. Functional trait-based approaches may help us better understand the nature of the diverse biotic responses and their underlying ecosystem changes. We explored patterns in diatom (Bacillar...

Cyanobacterial blooms in freshwater systems are a global threat to human and aquatic ecosystem health, exhibiting particularly harmful effects when toxin-producing taxa are present. While climatic change and nutrient over-enrichment control the global expansion of total cyanobacterial blooms, it remains unknown to what extent this expansion reflect...

Increasing proportions of the global population are exposed to floods, including many living in the Yellow River floodplain. Since records were first kept in 602 BCE, there have been~1500 floods on the Yellow River, resulting in the death of millions of people. Counteracting increased flood risk requires an understanding of the relationship between...

Long-term changes in diatom community composition provided important insights into how multiple stressors affected shallow, macrophyte-dominated Lake Opinicon, Ontario (Canada) over the past ~ 200 years. A previous paleolimnological study of a sediment core collected in 1995 found that diatom responses to numerous large-scale cultural disturbances...

Lakes worldwide are under threat by a myriad of environmental stressors that have been increasing in number and magnitude. These stressors can be regional such as climate change, or local such as nutrient-rich runoff, invasive species, and road salt contamination, to name but a few. To protect lake ecosystems from further deterioration, we need lon...

Many paleolimnological studies from the Northern Hemisphere have shown how diatom assemblages preserved in dated lake sediment cores have responded to anthropogenic climate warming over the past ~100 years. In contrast, diatom records from lakes in the southeastern Tibetan Plateau have typically registered minimal compositional change during this r...

Our planet is being subjected to unprecedented climate change, with far-reaching social and ecological repercussions. Below the waterline, aquatic ecosystems are being affected by multiple climate-related and anthropogenic stressors, the combined effects of which are poorly understood and rarely appreciated at the global stage. A striking consequen...

The lakes around Yellowknife (Northwest Territories, Canada) have been impacted by multiple environmental stressors throughout the 20th and early 21st centuries. Here, we have synthesized diatom assemblage data from ten lake sediment cores from the Yellowknife area and used a landscape-scale paleolimnological approach to investigate the cumulative...

Seabirds are important biovectors of contaminants, like mercury, moving them from marine to terrestrial environments around breeding colonies. This transfer of materials can have marked impacts on receiving environments and biota. Less is known about biotransport of contaminants by generalist seabirds that exploit anthropogenic wastes compared to o...

AnthropogenicClimateclimate changeClimate change and the recent increase ofSaharan dustSaharan dust depositionSaharan dust depositionare potentially affectingSierra NevadaSierra NevadaAlpine lakesalpine lakesLakes. In this chapter, we summarize the results of paleolimnological research conducted to track recent environmental and ecological changes...

Autochthonous and allochthonous organic carbon (OC) are important carbon sources for zooplankton in lakes, and changes in the abundance and proportions of those sources may affect zooplankton community composition and lake ecosystem function. Nevertheless, long-term changes in assimilation of autochthonous and allochthonous carbon by zooplankton an...

Gajewski offers a formal comment on Griffiths et al. (2017), a paper that explored how microclimates and their varying ice cover regimes on lakes and ponds in Arctic regions modified the diatom assemblage responses to recent warming. One of Gajewski's main criticisms is that the microclimate classification scheme used in Griffiths et al. (2017) is...

Mining and smelting activities have strongly influenced the Sudbury region (Ontario, Canada) since the late 19th century, leading to acidification and metal contamination in many local ecosystems. Regulations on restricting acidic emissions were enacted in the 1970s, after which a considerable volume of paleolimnological work was completed to study...

Lakes worldwide are under threat by a myriad of environmental stressors that have been increasing in number and magnitude. These stressors can be regional such as climate change, or local such as nutrient-rich runoff, invasive species, and road salt contamination, to name but a few. To protect lake ecosystems from further deterioration, we need lon...

Freshwater biodiversity is in a state of crisis. The recent development of a global emergency recovery plan to “bend the curve” for freshwater biodiversity lacks the necessary details for implementation in a regional context. Using Canada as an example, we describe a toolbox intended to equip decision-makers and practitioners with evidence-based to...

Anthropogenic stressors affect lakes around the world, ranging in scale from catchment-specific pollutants to the global impacts of climate change. Canada has a large number and diversity of lakes, yet it is not well understood how, where, and when human impacts have affected these lakes at a national scale. The NSERC Canadian Lake Pulse Network so...

Lakes in the Arctic and tropical Andes are experiencing some of the largest temperature increases on the planet with coeval marked limnological changes, but little data exist on water balance parameters from these regions. Here, we present a unique data set of water stable isotope composition (δ¹⁸O and δ²H) from a suite of 49 water bodies in the Ca...

This special issue, entitled “Paleolimnology and Paleoecology in a Rapidly Changing Asia”, was initiated during the third China Workshop on Lake Paleoecology that was held in Kunming, China, in December, 2019. Here, we summarize some of the key findings from the 10 papers that are included in this issue. The papers present sediment surveys of lakes...

Since the 1950s, the widespread application of road salt for winter road maintenance and safety in cold regions has led to increased conductivity levels in many freshwater systems. Salting practices have adversely affected freshwater biota; however, the magnitude of ecological impacts may vary by species and ecosystem. Here, we examine diatom assem...

Peatland carbon accumulation generally increased during past intervals of natural warming. With recent anthropogenically-dominated warming being unprecedented over the past ∼2000 years, however, it is unclear how peatland carbon dynamics may operate compared to those under historical natural warmings. Here we examine the impacts of the recent warmi...

Salinization of freshwater lakes, largely linked to road salt (NaCl) runoff, is a serious threat to zooplankton across North America and Northern Europe. Chloride (Cl⁻) can be toxic to many freshwater species, and so water quality guidelines have been created to regulate it and protect aquatic life. However, these guidelines may not adequately prot...

Farming of carnivorous animals for pelts potentially contaminates nearby ecosystems because animal feed and waste may contain persistent organic pollutants (POPs) and metals. Mink farms in Nova Scotia (NS), Canada, provide mink with feed partially composed of marine fish meal. To test whether mink farms potentially contribute contaminants to nearby...

Lake sedimentation rate represents a synthetic metric of ecosystem functioning. Many localized studies have reported a significant association between land use/land cover changes and lake sediment mass accumulation rates, with a few global syntheses echoing these findings at larger scales. In the literature, studies evaluating lead‐210 (210Pb) for...

Seabird population size is intimately linked to the physical, chemical, and biological processes of the oceans. Yet, the overall effects of long‐term changes in ocean dynamics on seabird colonies are difficult to quantify. Here, we used dated lake sediments to reconstruct ~10,000‐years of seabird dynamics in the Northwest Atlantic to determine the...

Peatlands often develop around active volcanoes. However, little research has been conducted on the impacts of volcanic eruptions on peatland development. Here, we investigated the impacts of Holocene volcanic eruptions of the Changbaishan Volcanic field on the development of Dongfanghong peatland by using basal peat ages, geochemical and palaeo...

Human activities in the headwaters of the Carleton River Watershed (southwest Nova Scotia, Canada) are suspected to have led to nutrient enrichment of freshwaters, resulting in downstream effects. However, the presence of multiple nutrient sources in the headwaters, including mink fur farming and land-based aquaculture, have made it difficult to di...

Base metal smelting activity around Sudbury (Ontario, Canada) has persisted for over a century, emitting metals and acidifying contaminants that affected lakes downwind of smelter stacks. Although considerable research has been directed toward the paleolimnological study of diatoms and chrysophytes in the region, relatively little comparable work h...

Campbell J, Libera N, Smol JP, Kurek J. 2022. Historical impacts of mink fur farming on chironomid assemblages from shallow lakes in Nova Scotia, Canada. Lake Reserv Manage. 38:80–94. Mink fur farms in southwestern Nova Scotia, Canada, are a suspected source of nutrients that have likely contributed to water quality issues in nearby lakes. Despite...

The Changbaishan volcanic field is one of the most dangerous active volcanic fields in Northeast Asia. Its Millennium eruption at 946-947 CE is considered to be one of the world's largest explosive eruptions over the past 2000 years. However, little attention has been paid to the other Late Holocene tephrostratigraphic sequence of this volcanic fie...