Abstract
Mangroves in small islands are critical resources for the stability of the island and the livelihood of local coastal communities. However, scientific inventories of mangroves in small islands are rare due to their limited distribution. Considering this, the present study was conducted during 2014–2015 to determine the species composition, biomass, vegetative carbon stock and spatial distribution of mangroves at Neil Island, one of the small islands of the Andaman and Nicobar Islands, India. The spatial locations of different species of mangroves identified from our extensive field surveys were compared with high-resolution images, and the coverage of mangroves (genus level distribution) was interpreted entirely based on the elements of tone and texture. The results show that the mangroves of Neil Island consist of 17 true mangrove species belonging to 12 genera in eight families. The co-existence of all three Indo-West Pacific mangrove species of the genus Rhizophora (Rhizophora apiculata, Rhizophora mucronata and Rhizophora stylosa), and their hybrids (Rhizophora × annamalayana, Rhizophora × lamarckii and Rhizophora × mohanii) shows that this island is a unique place for studying the hybridization and speciation of Rhizophora, a worldwide dominant mangrove genus. Rhizophora mucronata was found to be the dominant species in terms of density, basal area and biomass estimated from forest structural assessments using the quadrat method. The mean density and basal area were 1162 trees ha−1 and 28 m2 ha−1, respectively. The mean above-ground biomass was 271 Mg ha−1, while the mean below-ground biomass was 104 Mg ha−1. The total mean biomass of Neil Island mangroves was 375 Mg ha−1 and its corresponding vegetative carbon stock was 171 Mg C ha−1. The present study provides a practical approach to species-level mapping and assessment to gain site-specific knowledge of the mangroves of Neil Island. Since mangroves are vital for small islands such as Neil Island to cope with rising sea level and increases in natural calamities, the baseline scientific information provided by this study will be beneficial for Integrated Island Management.
About the authors
Dr. Sivakumar Kannan is an associate professor, CAS in Marine Biology, Annamalai University. He is teaching biological oceanography for post graduate students and pursuing research on molecular diversity of marine flora. Recently, he evinced interest in understanding the mangrove diversity found in the islands and atolls, globally. Environmental DNA (eDNA) envisaged understanding of mangroves and their conservation is his future aim of research.
Dr. P. Ragavan is a post doctoral research fellow in the Geosciences Division at Physical Research Laboratory, India. He pursued his PhD degree in marine biology. His area of interest is the taxonomy, ecology, molecular phylogenetics and biogeochemistry of mangroves and seagrasses. His more recent research has concentrated on the carbon dynamics of vegetated coastal habitats of India and environmental DNA (eDNA) metabarcoding of mangroves.
Mr. K. Gopalakrishnan is a research scholar in Centre of Advanced Studies in Marine Biology, Faculty of Marine Sciences, Annamalai University. He is pursuing his PhD in marine biotechnology. His area of research is on molecular diversity of mangrove associated microflora and their bio prospecting.
Dr. Maryam Salah was a research scholar in Centre of Advanced Studies in Marine Biology, Faculty of Marine Sciences. She pursued her PhD in marine biotechnology. Her area of interest is on molecular diversity of mangrove associated microflora and their bio prospecting.
Dr. K. Balasubramani is currently affiliated to School of Earth Sciences, Central University of Tamil Nadu. His main research focus is on exploring applications of geospatial technologies in natural recourses and disaster management. He is interested in conducting multi-disciplinary research and published notable works on watershed modelling with emphasis on sustainable land use planning, hazard and vulnerability assessment, landscape dynamics and spatial epidemiology in reputed journals.
Acknowledgements
We thank the Andaman & Nicobar Administration, Department of Environment and Forests (Andaman and Nicobar Islands) and Zoological Survey of India (Regional office, Port Blair, Andaman and Nicobar Islands) for providing us with necessary support. We also thank the Director, CAS in Marine Biology, Annamalai University for his encouragement and Dr. Praveen Balabaskaran Nina, Central University of Tamil Nadu and Prof. L. Kannan for offering valuable comments.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: None declared.
Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
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