Aquatic Ecosystems

Term Definition
Limnology study of physical, chemical, and biological conditions of fresh water
PAR photosynthetically active radiation
Metalimnion zone in which temperature changes rapidly
Holomictic lake mixes from top to bottom during annual mixing cycle
Dimictic spring/fall turnover, mixes twice
Monomictic turn over only in summer
Polymictic mix every few days, year round
Amictic no turn over, ice covered
Meromictic deep or chemically stratified lakes that only mix partially due to lack of energy to overcome stratification
TDS total dissolved solids
pH potential hydrogen
pH measure of H+ ions on a solution
Alkalinity ability to resist change in pH
Buffering Capacity the capacity of a water body to accept H+ ions
High Buffering Capacity ability to accept H+ ions without a change in pH
Low Buffering Capacity inability to accept H+ ions without change in pH
DOC dissolved organic carbon
DOC organic compounds that pass through a mesh size of 0.45mm
Turnover important to replacement of O2 in hypolimnion, since thermal restricts distribution of O2 (summer and winter)
Trophic Levels all organisms in an ecosystem can be placed in trophic levels depending on what energy source they rely on and how they provide energy for other organisms in the food web
Edaphic nutrients available to water from weathering soils
Lake Morphometry volume, surface area, mean depth
Retention Time the time required to replace entire lake volume. time taken from entry to exit for every single molecule
To determine trophic status of a lake physical and chemical parameters can be used
Photosynthesis uses light as its source for energy
Chemosynthesis uses reduction of chemical compounds as its source of energy
Primary Producers autotrophs – from the base of the food chain
Phosphorus relatively unavailable. sources: run off, precipitation, groundwater
Loading Rate influenced by: land use, human activities, morphology. high loading rate, high productivity. for plant growth – algae blooms
Phosphorus exists in two forms: soluble reactive phosphorus (srp), particulate P
SRP cycles
P settles
Nitrogen used by plants to produce proteins. fixed by blue-green algae
Current issues in Ontario Lakes -habitat loss. -phosphorus loading. -long-term monitoring

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