BLUE-GREEN ALGAE AND THEIR CONTRIBUTION TO GLOBAL BIOGEOCHEMICAL CYCLES – A REVIEW.

Abstract

Blue-green algae (cyanobacteria) are ancient photosynthetic prokaryotes that play a crucial role in global
biogeochemical cycles. They contribute significantly to carbon sequestration, oxygen evolution, and
nitrogen fixation, thereby influencing ecosystem productivity and climate regulation. Widely distributed
in aquatic and terrestrial environments, cyanobacteria regulate the cycling of essential nutrients such as
carbon, nitrogen, phosphorus, and sulfur. Their ability to fix atmospheric nitrogen enhances soil fertility
and supports primary productivity. In addition, cyanobacteria are involved in nutrient recycling,
maintaining ecosystem stability and resilience. Beyond their ecological importance, they have promising
applications in biotechnology, including biofertilizers, biofuels, and wastewater treatment. However,
under nutrient-rich conditions, certain species form harmful algal blooms that release toxins, posing
environmental and health risks. This review highlights the ecological significance and dual role of
cyanobacteria in sustaining and challenging ecosystem balance.