Abstract: Cyanobacteria play a crucial role in marine ecosystems as primary producers of food and oxygen for various organisms while helping remove waste and toxic substances from the environment. They are essential to the carbon cycle and help regulate the climate. These marine autotrophs also aid in the absorption of essential elements and support diverse life forms. They help degrade organic compounds including petroleum hydrocarbons as well as heavy metals. Fluctuations in cyanobacteria populations can indicate ecosystem health, influencing both human well-being and wildlife. Their significance also extends to potential technological advancements, thus providing valuable resources for fields such as pharmacology, medicine, health care, biofuels, cosmetics, and bioremediation. However, some species produce toxins that pose risks to human health and marine organisms. Consequently, cyanobacteria are a major focus of research aimed at preserving and improving marine ecosystems-especially given the environmental damage caused by past and potential future conflicts. This review highlights their roles in phycoremediation and other industrial and biotechnological applications with a particular focus on the Arabian Gulf region.

Qatar and other Gulf States have a diverse range of marine vegetation that is adapted to the stressful environmental conditions of seawater. The industrial wastewater produced by oil and gas activities adds further detrimental conditions for marine aquatic photosynthetic organ-isms on the Qatari coastlines. Thus, these organisms experience severe stress from both seawater and industrial wastewater. This review discusses the biodiversity in seawater around Qatar, as well as remediation methods and metabolic pathways to reduce the negative impacts of heavy metals and petroleum hydrocarbons produced during these activities. These methods include phyto-stabilization phyto-accumulation, phyto-volatilization, and phyto-degradation. Phy-to-degradation in particular is discussed in detail, including metabolic pathways such as alkane and aromatic-compound degradation pathways. The role of microorganisms that are adjacent to or associated with these aquatic marine organisms is discussed, including rhizosphere biodeg-radation. In this type of biodegradation, exudates are released by plant roots and supply nutrients to microorganisms in the rhizosphere, which enhances their ability to degrade organic pollutants. Special attention is paid to mangrove forests and their roles in remediating shores polluted by industrial wastewater. Seagrasses (Halodule uninervis, Halophila ovalis, and Thalassia hemprichii) and seaweeds (Chlorophyta, Phaeophyta, and Rhodophyta) around the peninsula of Qatar are also discussed.