Aquatic Systems

Terms:
limnology, littoral, limnetic, and profundal zones, macrophytes, phytoplankton, zooplankton, diatoms, benthos, allochthonous, autochthonous, epilimnion, metalimnion, hypolimnion, thermocline, dimictic, monomictic, and merimictic lakes, oligotrophic, eutrophic

allochthonous:  Input, such as nutrients, into a system from outside that system.

autochthonous: Input, such as nutrients, into a system from within that system.

benthos: Plants and animals that live in bottom sediments in an aquatic system.

diatoms: An abundant unicellular or colonial algae characterized by silica walls.

dimictic lake: A lake that mixes twice per year, usually in temperate regions where temperature change with seasons causes the water to stratify in the summer, and mix in the spring and fall. 

epilimnion: Top layer of warm water in a stratified lake or other body of water.

eutrophic: A condition in a lake or other body of water that is characterized by lush phytoplanktonic growth followed by high amounts of decay in the bottom resulting in depletion of oxygen in the water column.

hypolimnion: Bottom layer in a stratified lake or other body of water where little light penetrates.

limnetic zone:  The area of a lake where light penetrates down to a lower boundary at the light compensation point. 

limnology: The study of freshwater systems.

littoral zone: The area in a lake or stream where sunlight reaches the bottom.

macrophytes: Rooted or free-floating multi-cellular plants in an aquatic system.

merimictic lake:  A lake that seldom mixes because it is in a relatively stable environment.

metalimnion: Middle layer in a stratified lake or other body of water where temperature changes most rapidly with depth, also known as the thermocline.

monomictic lake: A lake that mixes only once per year.

oligotrophic: A condition of a lake or other body of water characterized by low nutrients, low productivity, and high oxygen levels in the water column.

phytoplankton:  Unicellular or colonial free-floating plants in an aquatic system.

profundal zone: The area of a lake below the light compensation point to the bottom.

thermocline: Middle layer in a stratified lake where temperature changes most rapidly with depth, also known as the metalimnion.

zooplankton: Floating or free-swimming animals in an aquatic system.