Abstract:
Mangrove ecosystems are significant coastal zones that help deliver various ecological functions, which
include shoreline stability, carbon capture, nutrient cycling, and marine biodiversity protection.
Mangrove ecosystems of high extent and rich biodiversity have been observed in Mannar, which is in
northwestern Sri Lanka. However, current scientific evidence about the identification of mangrove
species through field-based research in this area has not been updated. The current study sought to find
out which of the recorded mangrove species in the literature are found in Mannar using the field survey
method. For this purpose, five sites, including Achankulam, Naruvilikulam, Vankalai, Pappamoodai,
and Vidataltivu, were selected since these sites have rich biodiversity and mangrove ecosystems. In
each site, a transect (200m) was set perpendicularly from the shoreline, and ten 10m x 10m (100m²)
quadrats were randomly placed along the line transect in each site, amounting to fifty quadrats in total
in March of 2026. Mangrove species were identified using morphological characteristics, and species
richness, together with frequency of occurrence across sampling sites, was analyzed. Six species of
mangroves were recorded in the study areas: Rhizophora mucronata, Avicennia marina, Ceriops tagal,
Lumnitzera racemosa, Excoecaria agallocha, and Pemphis acidula. Two mangrove species, R.
mucronata and A. marina, occurred in all five locations, suggesting that the two species have broad
ecological ranges. L. racemosa was observed at four locations, and C. tagal at three locations. Two
other species were found at two locations each: E. agallocha and P. acidula. The greatest diversity was
recorded in Pappamoodai (5 species) and Vidataltivu (5 species), while the least diversity was recorded
in Naruvilikulam (3 species) and Vankalai (2 species). The observed distribution generally agreed with
previous literature, although Bruguiera cylindrica, previously reported from Mannar, was not identified
during this study. The study was based on species occurrence rather than abundance, and it provides
updated field-based evidence on mangrove distribution in Mannar.
