Ecological status of sathurukondan mangrove wetland, Batticaloa, Sri Lanka: composition, diversity and vegetation pattern

Abstract

Sathurukondan wetland in the Batticaloa District contains valuable mangrove resources, yet baseline ecological information remains rather scarce. This study assessed mangrove vegetation from May to October 2023, focusing on species distribution, abundance, and diversity. A total of 59 line transects and 99 quadrats were established to compile a species checklist and evaluate community structure using diversity indices such as the Shannon–Wiener index, Pielou’s evenness, and Margalef richness. Vegetation patterns were further analyzed through relative density, frequency, dominance, and Importance Value Index (IVI). Results identified eight true mangrove species from six families, including five Least Concern (NC) and three Near Threatened (NT) species, along with nine associated species. Excoecaria agallocha was the dominant species with the highest ecological importance (IVI = 145.78), while Aegiceras corniculatum showed the lowest distribution. Other notable species included Lumnitzera racemosa, Sonneratia caseolaris, and Rhizophora apiculata. Overall diversity was low (H’ = 1.132), with low evenness (J = 0.544) and richness (d = 0.794), indicating limited heterogeneity and uneven species distribution. These patterns suggest ecological imbalance, potentially driven by natural conditions and increasing human pressures such as fishing and tourism. This study provides a crucial baseline for future conservation and management efforts.