Glossary of Lake Terms

This glossary was put together using some of the definitions from Water On the Web (http://wow.nrri.umn.edu/wow/index.html). We would like to thank them for their help!

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A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z

A

Abiotic: Not alive, not biological.

Acid: Below 7 on the pH scale of 0-14

Acid rain: Precipitation lower than the natural range of ~ 5.5. Acid rain occurs when sulfur dioxide (SO2) and nitrogen oxides (NOx) mix with the oxygen, water and other chemicals in the atmosphere to form different acidic compounds.

Adhesion: The tendency to want to adhere or come together. Water molecules tend to adhere together.

Adirondack Park: A 6-million acre park created in 1892 to help protect water and timber resources. Approximately half of the park is privately owned, the other half is protected forest preserve.

Algae: Simple single-celled, colonial, or multi-celled, aquatic plants.

Alkalinity: Acid neutralizing or buffering capacity of water; a measure of the ability of water to resist changes in pH caused by the addition of acids or bases and therefore, the main indicator of susceptibility to acid rain

Anoxia: Without dissolved oxygen

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B

Base: A substance which accepts protons (H+) and has a pH greater than 7 on a scale of 0-14; also referred to as an alkaline substance.

Basin: The area that surrounds the body of water and drains into that body of water.

Benthic: Refers to the bottom of the lake.

Biodiversity: The number and variety of species in a region. A diverse habitat is more healthy and can support more organisms than one that has been taken over by an invasive species.

Biotic: Alive

Buffer: A substance that tends to keep pH levels fairly constant when acids or bases are added.

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C

Carbon Dioxide: A gas that is colorless and odorless. CO2 is absorbed and incorporated by plants for photosynthesis in the "dark" cycles of photosynthesis.

Carnivore: "Meat" eaters; organisms that eat other organisms.

Chlorophyll: The green pigment in plants that transforms light energy into chemical energy in photosynthesis.

Clarity: How clear the water is.

Cohesion: The molecular force between particles within a substance that acts to unite them

Conductivity: Measures water's ability to conduct an electric current and is directly related to the total dissolved salts (ions) in the water.

Consumers: Animals that eat other animals to maintain their energy levels. Unlike producers, they can't make their own food through photosynthesis.

Cultural Eutrophication: The filling in of a lake or other water body due to runoff from human activity. Salt and sand from winter de-icing runs off the roads and into our waterways.

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D

Decomposition: The breakdown of organic matter by fungi and bacteria.

Deep water sampler: A device used to obtain water at different depths for sampling purposes. Kemmerer bottles and Van Dorn bottles are commonly used for this.

Delta: A deposit of sediment at the mouth of a stream or river.

Density: The mass of a substance or organism per unit volume (kg/cubic meter; grams/liter).

Detritus: Dead or decaying matter.

Dissolved Oxygen: The concentration of oxygen dissolved in water. Usually expressed in milligrams per liter or parts per million.

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E

Ecosystem: All of the organisms in an area and their relationship with each other, their surroundings and their chemical environment.

Epilimnion: The upper, warmer, lighter layer of water.

Eutrophication: The process by which a body of water acquires nutrients. This leads to excessive plant growth, and low water clarity.

Eutrophic lake: One that is high in nutrients. Water clarity is generally lower due to high amounts of plant growth, including phytoplankton.

Exotic Species: A species not native to the area in which it is being found.

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F

Fall turnover: When the layers of water in a lake are mixed as the warm water on the surface is cooled by falling temperatures and sinks to the bottom, pushing up warm water. Eventually the lake water will be one temperature from top to bottom.

Flow rate: The rate at which water moves by a given point; in rivers it is usually measured in cubic meters per second (m3/sec) or cubic feet per second (cfs).

Flushing rate: The retention time (turnover rate or flushing rate), the average length of time water resides in a lake, ranging from several days in small impoundments to many years in large seepage lakes. Retention time is important in determining the impact of nutrient inputs. Long retention times result in recycling and greater nutrient retention in most lakes. Calculate retention time by dividing the volume of water passing through the lake per year by the lake volume.

Food chain: The transfer of energy that occurs when a series of organisms eat (or decompose) the following one. An example: insect-fish-bear or the sequence of algae being eaten by zooplankton (grazers; herbivores) which in turn are eaten by small fish (planktivores; predators) which are then eaten by larger fish (piscivores; fish eating predators) and eventually by people or other predators (fish-eating birds, mammals, and reptiles).

Food web: A network of interrelated food chains.

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G

Geographic Information System (GIS): A computer system which allows for input and manipulation of geographic data to allow researchers to manipulate, analyze and display the information in a map format.

Global Positioning System (GPS): A satellite navigation system used to locate something, or someone. A GPS device gives you the latitude and longitude of your location using a constellation of satellites. Recreationally it is used in cars, boats, for hiking, etc.

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H

Herbivores: Plant-eating animals.

Hydrogen: Colorless, odorless and tasteless gas; combines with oxygen to form water.

Hydrology: The study of water's properties, distribution and circulation on Earth.

Hypolimnion: The bottom, and most dense layer of a stratified lake. It is typically the coldest layer in the summer and warmest in the winter. It is isolated from wind mixing and typically too dark for much plant photosynthesis to occur.

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I

Ice-out: The date when the ice breaks up and thaws.

Impervious surface: A surface that cannot absorb water, and prevents the soil from absorbing the water. Concrete is an impervious surface, as are most roads, driveways, and buildings.

Inflow: Water flowing into a lake.

Inorganic: Not composed of plant or animal materials.

Invasive species: A plant or animal, not native to a region. It does not have any predators in that region to keep its population in check. This species will spread rapidly and take over native habitat, reducing biodiversity.

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J

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K

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L

Lake George Park: An area of land that is roughly the Lake George Watershed and includes the lake. It is about 300 square miles, about half of which is privately owned. It was created in 1961 along with the Lake George Park Commission.

Landuse: The way the land is used: farmland, developed, woodland, forest, etc.

Limnology: The study of freshwater; including lakes, ponds, rivers, streams, etc.

Littoral: Near the shore.

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M

Mesotrophic lake: Moderately productive: contains a moderate amount of nutrients and algal growth.

Metalimnion: The middle or transitional zone between the well mixed epilimnion and the colder hypolimnion layers in a stratified lake. This layer contains the thermocline, but is loosely defined depending on the shape of the temperature profile.

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N

Native species: A plant or animal that has been in a region prior to European settlement.

Non-native species: A plant or animal that is not originally from a particular region. It does not necessarily represent a threat to native species.

Non-point source pollution: Pollutants that come from a land area not discharged from a pipe.

Nuisance species: A species that threatens the diversity of native species, usually by aggressive growing habitats.

Nutrients: Substances needed for growth by plants and animals. Phosphorus and nitrogen are two examples. To help plants grow, we generally apply fertilizer which contains nutrients like phosphorus and nitrogen. In a lake, too many nutrients can lead to algal blooms.

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O

Oligotrophic lake: A lake that is relatively unproductive. It has few nutrients and relatively few plants and algae. It tends to be very clear.

Omnivorous: Eats both plants and animals.

Organic: Composed of plant or animal (natural) materials.

Outflow: Where a lake discharges, or where water exits a lake.

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P

pH: A measure of the concentration of hydrogen ions.

pH Scale: A scale used to determine the alkaline or acidic nature of a substance. The scale ranges from 1-14 with 1 being the most acidic and 14 the most basic. Pure water is neutral with a pH of 7.

Phosphorus: Key nutrient influencing plant growth in lakes.

Photosynthesis: The process by which green plants convert carbon dioxide (CO2) dissolved in water to sugars and oxygen using sunlight for energy. Photosynthesis is essential in producing a lake's food base, and is an important source of oxygen for many lakes.

Phytoplankton: Microscopic floating plants, mainly algae, that live in bodies of water and that drift about because they cannot move by themselves or because they are too small or too weak to swim effectively against a current.

Potable: drinkable, safe to drink

ppb: Part-per-billion; equivalent to a microgram per liter (ug/l).

ppm: Part-per-million; equivalent to a milligram per liter (mg/l).

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Q

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R

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S

Secchi disk:
A black and white disk, usually 20 cm. in diameter. Measures the clarity of the water.

Sedimentation: The buildup of sediment in the water.

Septic system: An onsite system designed to treat and dispose of domestic sewage from a residence or business. It consists of a tank and a septic field. Wastes are decomposed by bacteria, but some waste still remains in the tank and needs to be pumped out periodically.

Sewage: Used water and waste (usually human excrement) carried through home or commercial pipes that go to a septic system or wastewater treatment facility.

Sewage sludge: The solid matter that settles out during the treatment of sewage.

Spring turnover: When lake water is mixed after ice-out and becomes one temperature throughout, until warmer weather causes the water to separate into layers (see hypolimnion, metalimnion, or epilimnion).

Stormwater discharge: precipitation that does not become absorbed into the soil (due to impervious surfaces), or is evaporated. Instead it flows into a nearby waterbody and usually carries contaminants with it.

Stratification: Layering (see hypolimnion, metalimnion, or epilimnion).

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T

Temperature:
How hot or cold something is as determined by a thermometer.

Trophic State: The nutrient level of a body of water. There are 3 levels: Eutrophic (high in nutrients), Mesotrophic, and Oligotrophic (low in nutrients).

Thermal stratification: The layer of water based on the density of water at different temperatures. Warm water is at the top; and cold water near the bottom.

Thermocline: A sudden drop in water temperature over a short distance. It is surrounded by the epilimnion above and the hypolimnion underneath. Cold water fish are usually found near or below the thermocline.

Topography: The physical or surface features of an area.

Total dissolved solids (TDS): The dissolved solids found in water that consist of organic and inorganic matter.

Tributary: A smaller river or stream that flows into a larger body of water.

Turbidity: The amount of particles in the water that allow for clarity. (How clear the water is).

Turnover: A thorough mixing of all the layers in a lake. It usually occurs in the spring and/or fall in deeper lakes.

Two-story fishery: A fishery that can sustain both warm water fish (bass, catfish, etc.) and cold water fish (salmon, trout, etc.)

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U

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V

Vegetative Buffer:
Plants at the shoreline that stabilize the shoreline and help keep contaminates from lawns and runoff from entering the water.

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W

Wastewater:
Used water and waste that flow from homes or commercial businesses that eventually goes to a treatment plant. Sewage is another term for it, but wastewater can also include stormwater and runoff from streets.

Watershed: The land that surrounds and drains into a body of water.

Weed: A plant that is considered undesirable. It may be native but it is unwanted where it is, such as a dandelion in a grass lawn.

Wetland: Land that is permanently or temporarily wet, often due to the water table. It is usually characterized by plants that require or tolerate wet soil to grow.

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X

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Y

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Z

Zooplankton:
Small microscopic animals found in water.

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