academic journal: a periodical publication for the scholarship of a particular discipline (often peer-reviewed).

acid rain: rain or any other form of precipitation that is unusually acidic (i.e. below pH 5.7) and often has negative ecological impacts.

algal bloom: a loose term referring to a rapid increase in the algal density of an aquatic system.

alpha dating: chronological dating techniques based on the measurement of alpha particles (i.e. helium nuclei) emitted from a radioisotope.

Ambrosia: a genus of flowering plants within the Asteraceae family commonly referred to as “ragweed”. In eastern North America, an Ambrosia rise in the pollen record can be used as an indicator for the time of European settlement.

Anthropocene: the proposed geological epoch characterized by the acceleration of significant human impacts on the Earth during the mid-20th century.

bioindicator: species or communities that are so closely associated with particular environmental conditions that their presence can be used to infer the presence of those conditions.

brominated flame retardants: a group of organobromine compounds commonly used to reduce the flammability of consumer products. Long-term changes in their concentrations within lake sediments can be used as a chemical paleoindicator.

C2: a Microsoft Windows program for the analysis and visualisation of ecological and palaeoenvironmental data (the most recent release can be found here).

calibration set: also known as a training set is a set of surface sediment samples used to identify the optima and tolerances to environmental conditions of a particular indicator group, often used to develop a transfer function.

Canoco: a Microsoft Windows program for multivariate statistical analysis using ordination methods (the most recent release can be found here).

carbon-14 (14C): also known as radiocarbon is a naturally occurring radioisotope of carbon that has a half-life of ~5700 years. Used in paleolimnology to date biological materials that are less than ~50, 000 years old.

cesium-137 (137Cs): a radioisotope with a half-life of ~30 years that is associated with the fallout from nuclear weapons testing.

Chaoborus: a genus of small flies commonly referred to as “phantom midges”. The chitinized mandibles of Chaoborus‘ aquatic larval stages preserve well in sediments and are used in paleolimnology as a bioindicator of historical fish populations and/or deepwater oxygen conditions.

charcoal: a lightweight black carbon residue usually produced through the heating of wood or other organic materials in the absence of oxygen. Charcoal is used in paleolimnology as an indicator of regional fire history.

chironomids: members of the Chironomidae, a family of flies with aquatic larval stages whose chitinized remains preserve well in lake sediments. Chironomids are used in paleolimnology as a bioindicator for several environmental variables including deepwater oxygen conditions.

chronology: the science of locating events in time. In paleolimnology a chronology typically refers to the age-depth relationship of the sediments over the time period represented by the sediment core.

chrysophytes: members of the Chrysophyceae a large group of algae found mostly in freshwater. The siliceous scales and cysts of some chrysophyte taxa are used as an indicator of pH and nutrient conditions.

citation: a reference to a published source in order to acknowledge the relevance of prior work to the topic of discussion.

climate change: the ongoing rise of the average temperature of the Earth, and the related changes to climate and weather patterns.

cluster analyses: statistical approaches to group a dataset so that items within a group (or cluster) are more similar (in some sense) to each other than to items in other groups (clusters). In paleolimnology these approaches can be used temporally (i.e. to identify similar time periods within a sediment core) or spatially (i.e. to identify similar sites/lakes).

cyanobacteria: a phylum of bacteria that obtain energy through photosynthesis.

dating: see chronology.

detrended correspondence analysis (DCA): multivariate statistical technique able to find the main factors or gradients in large, species-rich, but sparse data sets.

DECORANA: the original software (FORTRAN) tool to perform DCA developed by Mark Hill in 1979. The vegan R package contains an implementation of DECORANA as one of its functions.

diatoms: members of the Bacillariophyceae, a class of algae with cell walls made of silica that preserve well in lake sediments. Diatoms are a commonly used bioindicator for a variety of environmental variables including pH and nutrient conditions.

environmental DNA (eDNA): DNA collected from environmental samples rather than directly from an individual organism. In paleolimnology, this typically refers to DNA isolated from sediment samples.

eutrophication: nutrient enrichment of water bodies to levels that induce excessive algae growth.

extrusion: the process of forcing a material through an opening. In paleolimnology, extruding typically refers to the sectioning of a continuous sediment core by pushing it out of a coring tube at discrete intervals.

fossil pigments: chlorophyll derivatives and carotenoids preserved in lake sediments. Used in paleolimnology to reconstruct long-term trends in aquatic primary productivity.

freeze corer: device used to collect sediments by freezing the sediments to itself. Typically a wedge-shaped device that can be filled with a coolant such as dry ice. The corer is lowered into sediments and allowed to sit until the sediments freeze to the supercooled side. This type of corer can retrieve exceptional samples of near-surface sediments.

gamma dating: chronological dating techniques based on the measurement of gamma radiation emitted from a radioisotope (e.g. lead-210 and cesium-137).

ggplot2: an R package for ‘declaratively’ creating graphics following the principles described in “The Grammar of Graphics” by Leland Wilkinson.

Global Boundary Stratotype Section and Point (GSSP): an internationally agreed upon stratigraphic reference point that defines the lower boundary of a geologic stage.

grain size: the diameter of individual grains of sediment.

gravity corer: device used to collect undisturbed samples of near-surface sediments. Typically deployed by rope and allowed to penetrate into the sediments under its own weight. The maximum length of the core that can be retrieved is dependent on the weight of the device and the density of the sediments.

guano: the accumulated excrement of seabirds and bats.

harmful algal bloom (HAB): a bloom of algae (or cyanobacteria) in marine or freshwater ecosystems that can harm (or kill) other organisms through reduced oxygen concentrations and/or the release of toxins.

high-performance liquid chromatography (HPLC): an analytical chemistry technique used to separate, identify, and quantify the components of a mixture.

Holocene: the current geological epoch that spans from the end of the most recent glacial period (~11,700 years ago) to the present-day.

Intergovernmental Panel on Climate Change (IPCC): the United Nations body for assessing the science related to climate change (more info can be found here).

internal loading: the release of phosphorus from lake sediments back into the water column under anoxic conditions.

International Paleolimnology Association (IPA): organization dedicated to the advancement of the science of paleolimnology and its applications, while also promoting the interests of paleolimnology globally (more info can be found here).

International Society of Limnology (SIL): the international scientific society that disseminates information among limnologists. Founded in 1922 as the International Association of Theoretical and Applied Limnology and Societas Internationalis Limnologiae (more info can be found here).

Journal of Paleolimnology (JOPL): academic journal dedicated to paleoenvironmental studies of river, wetland, peatland and estuary systems.(more info can be found here).

lead-210 (210Pb): a radioisotope with a half-life of ~22 years that occurs naturally as part of the uranium-238 decay series. Used in paleolimnology to date sediments that are less than ~150 years old.

loss-on-ignition (LOI): the weight loss of dried sediment after ~2h at ~550℃, used to estimate the amount of organic matter present in the sediment.

magnetic susceptibility: a measure of how much a material will become magnetized in an applied magnetic field.

modern analogs: samples where modern species assemblages are similar to past assemblages.

n-alkanes: class of lipids produced by plants that can be used to infer sources of organic matter.

Ontario-Québec Paleolimnology Symposium (PALS): an annual student-run conference for the discussion of ongoing studies and research within paleolimnology.

open access: principles and practices aimed at making academic products (i.e. articles, data, code, etc.) available online, free of cost or other barriers to access.

optima: the most favourable value of an environmental condition for the growth and reproduction of an organism. Differences in optima withing indicator groups are used to build transfer functions.

ordination: a technique in multivariate statistics to arrange data characterized by multiple variables so that similar objects are near each other and dissimilar objects are farther apart.

organochlorine: an organic compound containing at least one covalently bonded atom of chlorine. Groups of these compounds studied in paleolimnology include pesticides and polychlorinated biphenyls (PCBs).

ostracods: members of the Ostracoda, a class of small aquatic crustaceans with calcareous carapaces that can preserve in lake sediments. The stable isotope composition of ostracod remains can be used to infer information about paleoclimatic and paleohydrological conditions.

Paleoecological Investigation of Recent Lake Acidification (PIRLA): a large paleolimnological effort conducted in the 1980s to determine the timing, rate, and magnitude of acid deposition in North America.

paleolimnology: the interdisciplinary science that reconstructs the paleoenvironments of inland waters.

persistent organic pollutants (POPs): organic compounds that are resistant to environmental degradation. Due to their longevity, they can bioaccumulate with harmful ecological impacts.

pH: a (logarithmic) scale used to describe the acidity (or basicity) of an aqueous solution.

piston corer
plant lignins
plant macrofossil

pollen: the male microgametophytes of seed plants. Pollen is used in paleolimnology as an indicator of vegetation changes through time.

polychlorinated biphenyl (PCB): an organic chlorine compound once widely used as a dielectric and coolant fluid. PCBs are now classified as a persistent organic pollutant (POP) and probable human carcinogen.

polycyclic aromatic compound (PAC): an organic compound featuring several closed rings of atoms, primarily carbon. This group includes polycyclic aromatic hydrocarbons (PAHs).

polycyclic aromatic hydrocarbon (PAH): a chemical compound composed of multiple aromatic rings made up of only carbon and hydrogen. Found in coal and oil deposits and also produced by thermal decomposition (e.g. forest fires).

postdoctoral researcher (postdoc): an individual who continues to conduct research professionally after their doctoral studies.

R: a programming language and free software environment for statistical computing and graphics (the most recent release can be found here).

radioisotope: also known as a radionuclide is an atom that is unstable due to excess nuclear energy, that is released through radioactive decay. In paleolimnology, known half-lives of specific radioisotopes (e.g. carbon-14, cesium-137, lead-210) are often used to develop age-depth models for sediment cores.

rioja: an R package for the analysis of Quaternary science data. It contains functions for constrained clustering, transfer functions, and plotting stratigraphic data.

road salt: sodium chloride applied to roads during winter as a public safety measure for de-icing and anti-icing. A growing environmental concern, A growing environmental concern, due to the profound impacts on aquatic life when salt enters streams, rivers and lakes.

Royal Society of Canada (RSC): Canada’s National Academy that promotes Canadian research and scholarly accomplishment, recognizes academic and artistic excellence, and advises governments, non-governmental organizations and Canadians on matters of public interest (more info can be found here).

sediment core: a sample collected from a lake basin that captures the depositional history of the lake in stratigraphic layers (i.e. youngest sediments at the top increasing in age with depth).

Society of Canadian Aquatic Sciences (SCAS): A scientific society formed in 2022 to represent all aspects of aquatic sciences in Canada. A joining of the former Society of Canadian Limnologists (SCL) and the Canadian Conference for Fisheries Research, two organizations that had been meeting together annually since 1979 (more info can be found here).

Society of Canadian Limnologists (SCL): the Canadian chapter of SIL dedicated to providing a Canadian forum to discuss limnological research and issues, promoting aquatic research in Canada, and supporting the integration of young Canadian limnologists in the research community (joined the Canadian Conference for Fisheries Research in 2022 to form the Society of Canadian Aquatic Sciences).

space-for-time substitution: the approach used in paleolimnology to apply modern spatial information to the temporal information preserved in historical archives (e.g. sediment cores).

spectral analyses
stable isotopes

straight chain alkanes: see n-alkanes.

sulfur dioxide (SO2): a major air pollutant and precursor to acid rain.

Surface Waters Acidification Program (SWAP): a large paleolimnological effort conducted in the 1980s to determine the timing, rate, and magnitude of acid deposition in the United Kingdom and parts of northwestern Europe.

tephra: refers to the airborne pyroclastic material ejected during a volcanic eruption. Tephra layers in sediments can be associated with specific volcanic events to provide dates that have a high degree of certainty.

testate amoebae: a polyphyletic group of single-celled organisms with a shell (or test) that preserves well. Sensitivity of individual taxa to environmental conditions such as temperature, pH, and conductivity, have prompted their use as bioindicators in peatland, freshwater, and coastal environments.

Tilia: a Microsoft Windows program designed for managing and graphing paleontological data and metadata, especially stratigraphic data. (the most recent release can be found here).

tolerance: the range of values of an environmental condition where an organism is able to grow and reproduce. Differences in tolerances within indicator groups are used to build transfer functions.

training set: see calibration set.

transfer function: an inference model to describe the relationship between an indicator group and an environmental variable. Used to infer past values of the environmental variable from indicator assemblages preserved in deeper sediments.

varve: an annual pattern (composed of two sub-layers, one coarse and one fine) that can form in lake sediments as particles deposited in the spring are coarser (due to greater flow strength) than those deposited later in the year. Varves are sometimes visible to the naked eye, and can be used to develop chronologies for sediment cores.

vegan: an R package for ordination methods, diversity analysis and other functions for community and vegetation ecologists.

visible and near-infrared spectroscopy (VNIRS): measurement of absorption or reflectance at wavelengths of the visible spectrum and the adjacent portion of the infrared spectrum (between 400 and 2500 nm). Paleolimnological application of these techniques include inferences of dissolved organic carbon (DOC) concentrations in sediments.

visible reflectance spectroscopy (VRS): measurement of absorption or reflectance at wavelengths visible to the human eye (between 380 and 740nm). Paleolimnological application of these techniques include using the absorbance peak between 650 and 700nm to infer chlorophyll a concentrations in sediments.

X-ray fluorescence (XRF): an analytical technique that uses emission of “secondary” (or fluorescent) X-rays from a material bombarded with high-energy X-rays or gamma rays to obtain elemental/chemical information.