Pond Management: Glossary

Glossary

Anoxic - without oxygen, usually near the bottom of ponds during summer.

Algicide - chemical applied to a pond to control algal phytoplankton or metaphyton growth.

Alternative stable states - shallow ponds typically exhibit dominance either by aquatic plants or by phytoplankton; once established, each of these two communities tends to suppress the other.

Bathymetric map - map of a lake or pond with contour lines indicating depths.

Benthic algae/invertebrates - bottom-dwelling organisms associated with pond sediments, rocks or plant surfaces.

Biological control - reducing the abundance of a target species by importing or increasing the abundance of its natural enemies.

Bioengineering - bank stabilization using organic construction materials and living plants.

Biomanipulation - enhancement of zooplankton abundance (usually by reducing fish) in order to suppress phytoplankton growth.

Bluegill - Lepomis macrochirus, a member of the sunfish family Centrarchidae, especially consuming zooplankton and frequently stocked in ponds.

Carbon - an element (symbol C) serving as the structural base or organic molecules, and needed in large quantities by primary producers.

Chlorophyll- a - the green photopigment used by primary producers in photosynthesis, and frequently used as an indicator of the abundance of algae in ponds.

Cladocerans - members of the crustacean Order Cladocera and common amongst the zooplankton; most species are effective grazers on phytoplankton.

Compensation depth - the depth reached by 1% of surface light, and assumed to be the depth below which most plants and algae cannot sustain net growth.

Consumers - animals that directly or indirectly feed on primary producers such as plants and algae.

Discharge - the volume of water flowing into or out of the pond per unit time, often measured in cubic feet per second (cfs), liters per second (L/sec) or m3 per second.

Dissolved oxygen - oxygen (elemental symbol O) present as a gas dissolved in water; concentrations are determined largely by photosynthesis, respiration, water temperature and exchange with the atmosphere.

Drawdown - lowering the water level in a pond to consolidate sediments or control weedy plant species; often performed in winter.

Ecosystem - an ecological unit, such as a pond, involving interactions of a biological community of species and its abiotic environment.

Eutrophic - describing a pond with abundant nutrients and high rates of growth by primary producers.

Groundwater - water in the saturated soil below the water table, potentially contributing water to or receiving water from a pond.

Herbicide - chemical targeted specifically for the control of aquatic plants. Some products may also function as algicides (causing mortality of algae).

Hydraulic retention (residence) time - the average duration of a parcel of water within a pond, computed as [pond volume]/[discharge at the outfall].

Hypereutrophic - describing a pond with very high nutrient concentrations and excessive growth by primary producers.

Largemouth bass - a warmwater sport fish (Micropterus salmoides) often stocked as a piscivore in ponds of this region.

Macrophytes - aquatic plants (or occasionally large algae) that are clearly visible to the naked eye.

Metaphyton - free-floating clouds of filamentous algae, originating at the bottom of a pond but usually observed at or near the surface.

Microcrustacea - microscopic or barely visible invertebrates of the class Crustacea. Most species are consumers of algae, bacteria and dead organic materials associated with the periphyton and metaphyton.

Nitrogen - an important, and often growth-limiting nutrient (symbol N); although found in water in a number of other forms, only nitrate and ammonium are directly usable as a nutrient by primary producers.

Nutrient - an element critical to, and often limiting, the growth of primary producers; potentially limiting nutrients include phosphorus and nitrogen.

Organic - living or dead matter produced by organisms, and containing an abundance of carbon-based molecules.

Outfall - the location at which surface water leaves the pond, usually via a standpipe or over a dam.

Oxygen - oxygen dissolved is exchanged with the atmosphere, produced by the photosynthesis of primary producers, and consumed/required by all organisms; oxygen depletion may not only cause a pond to be unsuitable for some species, but also increases the solubility of phosphorus, often leading to excessive plant and algal growth.

Periphyton - the community of benthic algae found associated with the sediments and on rocks and plant surfaces.

Phosphorus - an important, and often critically limiting nutrient (elemental symbol P) needed by plants and algae for growth.

Photosynthesis - the incorporation of carbon into organic molecules by chlorophyll-a present in primary producers, requiring sunlight as an energy source.

Phytoplankton - the community of microscopic algae suspended in the water column.

Piscivorous - Having a diet consisting primarily of fish.

Primary producers - green plants and algae that obtain their nutrition through photosynthesis.

Riparian buffer - an area of land adjacent to a water body (e.g. pond) which is vegetated and maintained to trap sediments, nutrients and other chemicals, and also supplying food, cover and thermal protection to fish and wildlife.

Secchi disk - a disk 20 cm in diameter, either white or more commonly with white and black quadrants, lowered into a pond to its point of disappearance, and used as a measure of light penetration in the water column.

Surface runoff - overland flow from the watershed into a pond, whether via a stream or as sheet flow on the ground surface.

Watershed - the drainage basin or catchment, consisting of surrounding land that potentially contributes water, nutrients, and other materials to a pond.

Zooplankton - the community of microscopic invertebrates (especially cladocerans, copepods and rotifers) found in the water column.