Lake monitoring glossary of terms

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Table of lake monitoring terms
Ambient water quality A measurement of water quality immediately upstream (or outside) of the influence of pollution during average flow conditions.
Anions Ions with a negative charge. In water chemistry, the most common anions we look at are Chloride (Cl) and Sulfate (S)
Anoxia No dissolved oxygen measurable in water.
Biological Samples A term referring to data that are collected through laboratory analysis of water samples that are biological. These could include phytoplankton, zooplankton, benthic invertebrates, etc.
Blank sample (BLF) Blank samples are collected and analyzed to ensure that environmental samples have not been contaminated during the data-analysis process. The blank solution (deionized water) used is free of analytes so should not produce values when analyzed.
Benthic invertebrates Organisms that live on the bottom of a water body (or in the sediment) and have no backbone. They eat plankton, leaves, algae, and bacteria and, in turn, are eaten by fish, amphibians, birds, and other vertebrates.
Cations Ions with a positive charge. In water chemistry, the most common anions we look at are Calcium (Ca), Magnesium (Mg), Sodium (Na) and Potassium (K).
Chlorophyll-a A measure of the amount of algae growing in a waterbody. It is also used to classify the trophic status of a waterbody.
Dissolved oxygen (DO) The amount of oxygen that is present in water and is a direct indicator of a lake’s ability to support aquatic life.  Low oxygen conditions may also result in phosphorus being released from lake sediments.
Epilimnion The surface layer or top-most layer in a thermally stratified lake. The epilimnion can be several meters deep and the depth may fluctuate throughout the year.
Eutrophic Rich in nutrients and so supporting a dense plant population, the decomposition of which can negatively impact animal life by depriving it of oxygen. Eutrophic lakes are considered highly productive.
Eutrophication The process by which a body of water becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus leading to increased plant and algal growth. Any lake can experience eutrophication if nutrient loading is occurring.
External loading Phosphorus that enters the lake from overland runoff. There are multiple sources that contribute to external loading of lakes.
Field data Data that is collected by a sampler in the field during a sampling event. Field data for the BCLSMP typically includes secchi depth, surface temperature and in some cases a Dissolved Oxygen/Temperature profile using a field meter. Additional weather and water conditions may also recorded.
Field meter An electronic device used in the field to collect pertinent data. Consists of a hand-held reader attached to a cable which ends in a probe that measures specific parameters. The BCLSMP program typically uses YSI ProSolo ODO meters which allow the measurement of Dissolved Oxygen and Temperature at multiple depths throughout the water column. This data produces a lake profile and is an important tool in determining lake health.
Hypolimnion The lower layer of water in a stratified lake, typically cooler than the water above and can be relatively stagnant.  The depth of the hypolimnion may fluctuate throughout the year.
Hypoxia Low levels of dissolved oxygen in water (less than 4 mg/L)
Internal loading Phosphorus that is released from lake sediments to the water column during low oxygen conditions.
Lab data Data that is analysed from water samples at the lab and provided to the Ministry. Lab data for the BCLSMP program typically includes Total Phosphorus, Total Dissolved Phosphorus, Ortho-Phosphorus and Chlorophyll-a.
Lake profile A profile of lake temperature and dissolved oxygen readings. The profile is created by using a field meter to take measurements at regular intervals throughout the water column.
Level study A set of lake monitoring protocols that can be employed on a lake. They are categorized as Level 1, 2, 3, 4, 5 studies. See: Types of volunteer lake monitoring
Limnology The study of the biological, chemical, and physical features of lakes and other bodies of fresh water.
Marl lake A lake whose bottom sediments include large deposits of marl, a mixture of clay and carbonate minerals. They are typically clear water lakes as the carbonate binds the phosphorus making it unavailable for use by plants or algae.
Mesotrophic Having a moderate amount of dissolved nutrients. Mesotrophic lakes are moderately productive.
Metalimnion The layer of water in a stratified lake which lies beneath the epilimnion and above the hypolimnion, in which the temperature decreases rapidly with depth. The depth of the metalimnion may fluctuate throughout the year.
Monomictic lake A lake that experiences a complete mixing event, or turnover, once per year.
Oligotrophic Relatively low in plant nutrients and containing abundant oxygen in the deeper parts. Oligotrophic lakes are typically low productivity, clear water lakes.
Ortho-Phosphorus (OP) The form of phosphorus that is most readily available for use by algae and other aquatic plants for growth. OP is typically released from lake sediments during times of low oxygen and is therefore an indicator of internal loading.
Phytoplankton Microscopic algae that provide a source of food for zooplankton, fish and other aquatic animals.
Polymictic lake A lake that experiences a complete mixing event, or turnover, more than twice per year.
Quality assurance The maintenance of a desired level of quality in the data by means of attention to each stage of the sampling process (also see quality control)
Quality control A system of standards designed for each stage of the sampling process to ensure the best possible data quality is achieved (also see quality assurance)
Regular sample (REG) Regular samples are collected and analyzed to examine water quality conditions.
Replicate sample (REP) Replicate samples are collected and analyzed to ensure that environmental samples have not been contaminated during the data-collection process. The samples contain the same solution (lake water) as the Regular samples so should produce similar results when analyzed.
Requisition form Used by the sampler to communicate to the laboratory what type of analysis is required water samples. Also indicates to the lab important information on when and where samples were collected.
Sampling event Each unique date on which sampling is conducted. The program aims for a minimum of 12 sampling events per year during the open water season.
Secchi disk A plastic or fibreglass disk measuring 20 cm (8 in) diameter with black and white design. Attached to a rope or measuring tape, and usually weighted. Used to measure freshwater transparency or water clarity.
Stratification The settling of lake water into separate and distinct thermal layers. Stratification is a result of atmospheric warming and cooling, and water density.
Supersaturation Above normal levels of dissolved oxygen in water (greater than 12 mg/L)
Surface water temperature Water temperature at the waters surface, typically measured using a thermometer or field meter.
Temperature profile See Lake profile
Thermocline A steep temperature gradient in a body of water such as a lake, marked by a layer above and below which the water is at different temperatures. Usually occurs within the metalimnion.
Total dissolved phosphorus (TDP) The fraction of the total phosphorus which is in solution in the water (as opposed to being attached to suspended particles)
Total phosphorus (TP) A measure of phosphorus that includes both ortho-phosphate and the phosphorus in plant and animal fragments suspended in lake water. TP levels are more stable and an annual mean can be an indicator of the lake's water quality and trophic status.
Turnover / Overturn The rapid mixing of lake water from top to bottom. Lake turnover is a natural phenomenon that can occur in any lake during rapid changes in weather temperatures. Typically observed in spring and fall.
Van Dorn / Student Sampler The Van Dorn water sampler (sometimes called a student sampler) has been specially designed for the sampling of open water at depth.
Water chemistry A term that refers to data collected through laboratory analysis of water samples.
Water clarity See Secchi depth
Water column The vertical expanse of water stretching between the surface and the floor of a body of water.
Watershed A land area that drains rainfall runoff to a single outlet.  Watersheds range in size and contain lakes, streams and rivers.
Watershed study The analysis of a watershed and can focus on water pollution, aquatic life or other issues impacting the watershed.
Zooplankton Microscopic aquatic animals that feed on phytoplankton and provide a source of food for fish and other aquatic animals.