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ecological dictionary

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Abiotic

Parts of the ecosystem that do not have life, such as minerals.

Absorption

The introduction or uptake of one substance into another.

Abyssal zone

The middle of the ocean (between 3000 and 6000 meters deep). The animals that live in the abyssal zone are described as abyssal.

Acidity

The amount of hydrogen ions in a solution compared to hydroxide ions. It is expressed on a scale called pH, which stands for pouvoir hydrogène – French for hydrogen power. The pH scale runs from 1 to 14. A solution is called acidic if it has a pH value lower than 7, meaning it has a higher concentration of hydrogen ions than hydroxide ions. A solution with a pH higher than 7 is called basic.

Acid rain

Rain which is contaminated with compounds that make it acidic, such as sulfur dioxide and nitrogen oxides, that enter the atmosphere due to industrial gas emissions. The main source of acid pollution is from the burning of fossil fuels to run electricity generators.

Adaptation

The gradual variation in the characteristics of a plant or animal species as it adjusts to its environment.

Aerobic

To “require air”, where air usually means oxygen. Refers to an organism that can live in the presence of oxygen or needs it to survive, e.g. aerobic bacteria. (See also Anaerobic.)

Aerobic respiration

The process by which organisms that need oxygen for respiration and generating energy get that oxygen, either from air or water.

Alkalinity

The amount of hydroxide ions in a solution compared to hydrogen ions. It is expressed on the same scale as acidity, pH (see acidity).The pH scale runs from 1 to 14. A solution is called alkaline if it has a pH higher than 7, meaning it has a higher concentration of hydroxide ions than hydrogen ions, and is often called basic. A solution with a pH lower than 7 is called acidic.

Alkaloids

Basic nitrogen-containing compounds naturally occurring in plants. Many are pharmacologically active (i.e. act as drugs) and some are poisonous. Examples are: morphine, nicotine, quinine, and strychnine. (See also Alkalinity.)

Almacigo

A tree from the Burseraceas family, originally from Central America. It has medicinal properties and is also used to feed livestock.

Alpha radiation

One of three types of radiation (beta and gamma are the other two). Alpha radiation consists of particles with a positive charge, which are let loose when an element is transformed to another. Alpha particles are heavy and slow, making them less penetrating than beta and gamma radiation. Alpha particles can be stopped with a sheet of paper or our skin. However, when inhaled or consumed in food, they can cause intense biological damage, 10 or 20 times worse than gamma radiation. The highly charged alpha-particles damage cells and biomolecules, for instance by impairing the genetic code of the organism.

Amphibians

A group of animal species that live both on land and in water. Amphibians adapt their internal temperature to the temperature of the surrounding environment, and lay eggs without shells.

Anaerobic

Without air, where “air” usually means oxygen. It refers to an environment with low or no oxygen, or to organisms that can develop in such environments. Some organisms cannot live in the presence of oxygen and are called obligate anaerobes.

Anomaly

An anomaly is something that does not fit under common rules or theories. The term is used to describe organisms that are different from most individuals of the same species and age.

Anthropic

Relating to humans or the era of human existence.

Apartheid

A policy of racial segregation promoted by the Afrikaner National Party in South Africa. It was established in 1948 and abolished in 1989.

Aquaculture

Techniques or skills related to the cultivation of aquatic resources of rivers, lakes and oceans such as aquatic plants, fish, and other aquatic animals.

Association

A group of organisms with defined characteristics that live in an area with uniform environmental conditions.

Atmospheric pressure

The pressure from the weight of the air on the earth.

Autotrophs

Organisms that can grow on simple molecules found in the environment, e.g. algae and green plants.

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