Lake Morphology

Shoreline

Length of shoreline

Shoreline Development

Ratio of length of shoreline to length of circumference of circle of area equal to that of the lake

Littoral

Shallow with vegetation

Pelagic

No vegetation

Benthic

Bottom

Profundal

Bottom with no vegetation

Photic Zone

Upper sunlit water where photosynthesis occurs

Aphotic Zone

Lower water with less than 1% of light with no photosynthesis

Epilimnion

Near surface water

Metalimnion/thermocline

Middle waters, zone where temperature changes

Planar thermocline depth

Location of the max temperature gradient in thermocline

Hypolimnion

Deepest

Stratification

Layering based on difference in water density

Holomictic Lakes

Mixes completely every year

Monomictic

1 period of mixing each year (cold or warm)

Dimictic

2 periods of mixing and 2 periods of stratification each year

Polymictic

Mixes many times a year (cold or warm)

Meromictic Lakes

Never fully mix due to accumulation of more dense salty water in the deepest areas (chemically stratified)

Mixolimnion

Layers involved in mixing

Monimolimnion

Deepest layers of a meromictic lake that never mix with surface waters

Biogenic Meromixis

Input of salt due to biological activity

Ectogenic meromixis

External event brings salt

Crenogenic meromixis

Submerged saline spring brings dense water to deepest parts of lake

Merometric Lakes

Water in monimolimnion are warmer than overlying waters due to salty waters sinking

Isothermal

Similar temperature top to bottom

Fetch

Max straight-line distance in a lake in the same direction of wind

Riverines in reservoirs

Narrow, well mixed with high water velocity

Transitions in reservoirs

More similar to lakes with increased light transmission and increased plankton and macrophytes

Lacustrine Zone in reservoirs

Lake-like deepest areas