Studies on seaweeds diversity along the intertidal zone of islands of Gulf of Mannar Marine Biosphere Reserve, India for policy and management recommendation : Studies on seaweeds diversity along the intertidal zone of islands of Gulf of Mannar Marine Biosphere Reserve, India for policy and management recommendation

A two-year study was conducted to analyze and document the seaweed diversity available along the intertidal zone of islands of the Gulf of Mannar Marine Biosphere Reserve from May-18 to October-19 with four-month intervals. From the five consequent surveys, 137 seaweed species belonging to 32 families and 17 genera were recorded in the Gulf of Mannar islands. Among 137 seaweed species, green algae (48) was the highest, followed by red (48) and brown (41) were observed. A comparative study among all three seasons revealed that a higher number of seaweed species and diversity indices were recorded in post-monsoon and monsoon seasons, whereas a lower value was recorded in summer months. 30 species were commonly found in the Gulf of Mannar Biosphere Reserve islands and 44 species are found with restricted occurrence. The genus Caulerpa appeared as the most diversified genera (18 species) followed by Sargassum (14 species), Dictyota (8 species), Gracilaria (6 species), Turbinaria (4 species), and Hypnea (6 species). While comparing all 19 islands, the maximum number of species recorded in Appa and Hare island (n = 76) and minimum species recorded in Manaliputti island (n = 25). There were 10 seaweed species abundantly present in all 19 islands. Dictyota dichotoma, Halimeda gracilis, Padina pavonica, Sargassum polycystum, Turbinaria ornata were common. Both the indices clearly pointed out greater seaweeds diversity in all the islands except Manaliputti island and higher diversity value indicated the healthy nature of the seaweed ecosystems and islands of the Gulf of Mannar Marine Biosphere Reserve. HIGHLIGHTS: 1. First attempt to systematic document of the seaweed diversity exclusively in inter-tidal region of islands of Gulf of Mannar Marine Biosphere Reserve 2. Analyse the healthy nature of seaweed diversity Gulf of Mannar Marine Biosphere Reserve 3. Analysing seasonal impact, seaweed dominance, succession pattern in inter-tidal region of islands of Gulf of Mannar Marine Biosphere Reserve 4. Data generated in this study may act as baseline information for effective coastal management