Algal

Algal is an adjective relating to algae, a diverse group of photosynthetic organisms that inhabit aquatic environments and moist soils. They range from microscopic phytoplankton to large seaweeds and include several major lineages, such as eukaryotic microalgae and multicellular macroalgae, as well as cyanobacteria, which are prokaryotes commonly referred to as blue-green algae.

Taxonomy and diversity are complex: algae are not a single clade but a loose assembly defined by photosynthetic capability. They are typically divided into microalgae, which are mostly unicellular or small in size, and macroalgae, or seaweeds, which are multicellular. Major groups include green algae, brown algae, red algae, and the pigment-rich cyanobacteria, each with distinct cellular structures and life cycles.

Biology and physiology vary widely but share core features. Most algae perform oxygenic photosynthesis using chlorophyll a, with additional pigments that give green, brown, or red appearances. They store energy as starch or lipids and often have cell walls made of cellulose; diatoms, a type of microalga, have silica-based cell walls.

Life cycles among algae are diverse, with many alternating between haploid and diploid generations. Reproduction can be sexual or asexual, and environmental conditions often influence life-cycle expression. Some algae form symbiotic relationships with other organisms, such as corals, where they provide essential photosynthates.

Ecologically, algae are foundational primary producers in aquatic ecosystems, supporting food webs and contributing to global carbon and oxygen cycles. They can respond rapidly to nutrient availability, sometimes forming blooms. Harmful algal blooms may produce toxins and impact water quality, fisheries, and tourism.

Humans use algae in numerous ways: edible seaweeds, nutraceuticals like spirulina, and industrial products such as alginates, agar, and carrageenan. Research into microalgae also explores biofuels, pharmaceuticals, and bioremediation, highlighting both benefits and environmental considerations.