Algae

Algae are a diverse group of mainly photosynthetic organisms that occur in a wide range of aquatic and moist environments.

Algae are a diverse group of mainly photosynthetic organisms that occur in a wide range of aquatic and moist environments. They range from microscopic single-celled forms to large multicellular seaweeds and are important primary producers in many ecosystems. The term is used for a heterogeneous group rather than a single formal taxonomic lineage.

Definition and classification

Algae are commonly defined as photosynthetic, nucleus-bearing organisms that lack the specialized reproductive structures and true organs of land plants. They are generally described as organisms that lack true roots, stems, and leaves. Modern usage treats them as a heterogeneous group rather than one natural taxonomic division. Some sources include cyanobacteria in broader usage.

Habitat and diversity

Algae inhabit marine and freshwater environments as well as moist terrestrial surfaces. Some can live in extreme conditions such as snow, ice, and hot springs. Algal forms range from microscopic single cells to large multicellular seaweeds, including microscopic phytoplankton and large seaweeds such as kelps.

Ecological importance

Algae are important primary producers at the base of many food chains. They release oxygen through photosynthesis and contribute significantly to Earth's oxygen supply. They also help form habitats such as kelp forests and some coral reefs. In Canada, algae are relevant in freshwater systems, Atlantic and Pacific coastal waters, and Arctic environments, where they play major roles in food webs, oxygen production, and monitoring water quality.

Human relevance

Algae are used as food, in medicine, and in other commercial and scientific applications. Certain species can produce harmful algal blooms that affect water quality and other organisms.