Dolichospermum

Dolichospermum is a genus of filamentous, heterocystous cyanobacteria in the family Nostocaceae, order Nostocales. It comprises several species that were previously placed in Anabaena, and taxonomic revisions in the 21st century led to recognizing Dolichospermum as a distinct genus. Notable species include Dolichospermum flos-aquae, Dolichospermum lemmermannii, and Dolichospermum spiroides.

Morphology and physiology: Dolichospermum forms uniseriate trichomes made up of vegetative cells interspersed with specialized heterocysts used for nitrogen fixation. Some species also produce akinetes, resting cells that help survive adverse conditions. The trichomes are often embedded in a mucilaginous sheath and may occur as free-floating colonies or surface blooms.

Habitat and ecology: They inhabit freshwater and, in some cases, brackish environments. Dolichospermum is commonly found in nutrient-rich waters and is a frequent component of phytoplankton during warm months. Nitrogen fixation occurs in heterocysts under low-oxygen conditions, contributing to nitrogen cycling in aquatic ecosystems.

Health and management: Several Dolichospermum species have the capacity to produce cyanotoxins, and blooms can pose risks to drinking water supplies, livestock, and recreational users. Monitoring and management of blooms often focus on toxin potential, cell counts, and nutrient status of the water body.

Ecology and significance: Dolichospermum is of interest for its role in nitrogen cycling, its tendency to form harmful algal blooms under eutrophic conditions, and its relevance to water quality and ecosystem health.