Freshwater Ecology Glossary Terms

What is alkalinity

A measure of the availability of the water to resist a change in pH due to the presence of carbonate, bicarbonate, and hydroxides.

Define allochthonous material.

Material generated outside a particular habitat but brought into that habitat, such as debris brought in through a lake by a river.

What does anadromous mean?

Refers to organisms that live in the sea as adults and return to freshwater to spawn.

Describe the aphotic zone.

The portion of a lake where incident light level is less than 1%, resulting in total darkness.

What does autochthonous refer to?

Native substances generated within a particular habitat, or indigenous material.

What are back eddies?

Pools along a stream created behind rocks and snags where water swirls but delays its downstream passage.

Define biomass in the context of freshwater ecology.

The total weight of organisms per unit area at any given moment in time.

What characterizes catadromous fishes?

Fishes that spend most of their life in freshwater but migrate to salt water to spawn.

What is the compensation depth?

The depth at which the rate of photosynthesis equals the rate of respiration.

What are hydrographs?

Plots of discharge against time.

Describe the term 'ephemeral pools.'

Pools of water that have brief aquatic lives of a few weeks to months, typically less than 1 meter deep.

What does eutrophic mean?

A classification of a lake that is highly enriched with nutrients.

What is the difference between oligotrophic and eutrophic lakes?

Oligotrophic lakes have few nutrients, while eutrophic lakes are highly enriched with nutrients.

Define the riparian zone.

The vegetated area adjacent to a stream, typically extending 30 meters from the water's edge.

What is the primary function of the riparian zone?

To absorb or buffer chemical and physical extremes affecting the stream.

What is the profundal zone?

The part of a lake where light is too scarce to support plant growth, usually muddy.

What does the term trophic status refer to?

The enrichment status of a lake, classified as oligotrophic, mesotrophic, or eutrophic.

River Contunuum Concept

Physical, chemical and biological attributes of a stream change as a Continuum of gradients as stream order size increases its Headwaters to its mouth, and the structure and function of the benthic invertebrate Community from Headwaters to River mouth is strongly regulated by the gradient of allochthonous and autochthonous organic matter.

Shoreline Length

The length of the shoreline perimeter derived from the outline of the lake

Summer Thermal Stratification

This is part of the annual temperature cycles of lakes when the heating and mixing processes continue and eventually form three thermal layers in the lake

Trophic Status

Enrichment status of a lake. Lakes are classified as either Oligotrophic, mesotrophic, or eutrophic, depending on the amount of nutrients contained.

Trophogenic Zone

the region of a lake where photosynthetic production occurs in terms of biological productivity it is one of two different regions in a lake, either being the tropholytic zone or region of breakdown. Vernal Pools: seasonal wetland

Vernal Pools

seasonal wetlands

Watershed

An area of land that intercepts and drains precipitation and collects water for a particular stream or other water body; drainage basin, catchment

Winter Thermal Stratification

This is part of the annual temperature cycle of lakes when low density surface layer (under the ice) at 0° C and sits on top of a dense layer near 4°

Zooplankton

collectively all those animals suspended in the water of an aquatic habitat which are not independent of currents and water movements most organisms are microscopic and commonly include photos rotifers and small crustaceans