Mangrove species occurrence in relation to habitat types: Insights from the Maldives

Mangroves are salt-tolerant woody plants forming coastal intertidal ecosystems throughout tropical and subtropical regions. Their distribution is commonly described along estuarine environmental gradients, with salinity and inundation identified as key drivers. However, in the Maldives, an oceanic archipelago lacking river systems, mangroves occur as small, fragmented stands of vegetation within closed or semi-enclosed water bodies, and their distribution patterns remain poorly understood despite the critical ecosystem services they provide. This study investigates species–habitat associations across 40 mangrove habitats, classified into embayment, pond-based, and marsh-based habitats, focusing on the occurrence of five dominant species: Bruguiera cylindrica, B. gymnorrhiza, Lumnitzera racemosa, Ceriops tagal, and Rhizophora mucronata. Water salinity was also measured to support interpretation of species distributions. Pearson’s Chi-square tests detected significant associations between species occurrence and habitat type for the five species (p < 0.05), whereas differences in salinity among species were not statistically significant (Kruskal–Wallis test, p = 0.208). B. cylindrica (χ²=20.000, p < 0.001) was strongly associated with marsh-based habitats, occurring in all surveyed systems of this type, whereas B. gymnorrhiza (χ²=6.578, p = 0.034) was less frequent there; both species was observed across a wide range of salinities. L. racemosa (χ²=8.189, p = 0.020) occurred most frequently in pond-based mangroves and was more often found in low to intermediate salinity conditions. In contrast, R. mucronata (χ²=11.779, p = 0.003) and C. tagal (χ²=23.022, p < 0.001) were predominantly associated with embayment habitats, characterized by high salinity. These findings improve understanding of mangrove spatial distribution and provide guidance for habitat-specific conservation and restoration in the Maldives, where mangroves are critically endangered.