Potentially Invasive and Non-Native Algal Taxa in Iraq: Distribution, Ecological Risks, and Research Gaps

Invasive algal taxa represent an emerging but poorly quantified threat to Iraq’s freshwater ecosystems. Drawing on floristic surveys, recent molecular detections, and regional literature, this review synthesizes the current evidence regarding the occurrence of Didymosphenia geminata and Hydrodictyon reticulatum and identifies Leptolyngbya benthonica and Nostoc paludosum as cryptogenic cyanobacterial taxa requiring further ecological assessment. A preliminary qualitative risk evaluation identifies D. geminata and H. reticulatum as high-priority taxa for monitoring based on their documented invasion history elsewhere, potential ecological effects, and likelihood of introduction and spread. In contrast the cryptogenic cyanobacteria Leptolyngbya benthonica and Nostoc paludosum should be interpreted cautiously because they are recently detected taxa whose origin and ecological behavior remain uncertain. Potential ecological risks include competitive displacement of native periphyton, disruption of benthic food webs, oxygen depletion during decomposition, and habitat alteration through the formation of dense mats. Major knowledge gaps include the absence of baseline distribution data, continued reliance on morphology-based identifications, limited application of molecular tools, and the lack of standardized national risk-assessment frameworks. Addressing these gaps would improve Iraq’s ability to detect, monitor, and manage algal invasions, thereby safeguarding vital water resources under escalating climatic and anthropogenic pressures.