A mini-review on heavy metals accumulation in seaweed of India: prospects for phyco-remediation

Abstract

Heavy metals are major contaminants introduced through various anthropogenic and geogenic activities, affecting and altering the quality of coastal water bodies where seaweed inhabits. Metal contamination poses a significant threat to aquatic and human health. Among different remediation methods for these pollutants, phyco-remediation is emerging as an effective strategy due to the metal's accumulation potential in the seaweed and its feasibility. In the review, all along the Indian coastline, the diverse accumulated seaweed species are documented, investigated, and assessed for their potential for monitoring heavy metal remediation. Also, highlights about heavy metal pollution levels and related industrial sources are reported, which reflect the need for remediation. The biological mechanism for heavy metals removal and assimilation in seaweed is thoroughly described and linked to the absorption potential of seaweed. Since past 50 years, only about 61 seaweed species (7.05%) have been studied for accumulation purposes out of enumerated 865 diversified species along the Indian coast. Among all three different classes of algae, i.e., Chlorophyta (green algae), Rhodophyta (red algae), and Phaeophyceae (brown algae), Chlorophytes are found to be the most suitable heavy metal accumulators, and Ulva sp. is the most studied genus. Remarkably, for Fe heavy metals, Phaeophyceae species showed higher accumulation from the Uppanar Estuary, Tamil Nadu. This review covered the potential of most suitable seaweed species for phyco-remediation, while studying the spatiotemporal variability in metal concentration. It further provides a comprehensive understanding of the unique physiological adaptations of different seaweed species to heavy metal contamination.