Abstract:
Mangrove ecosystems are considered as complex and extraordinary ecosystems. The
mangrove ecosystem is composed of flowering halophytic shrubs and trees and living
creatures that maintain their connection with the flora. The interaction between these
two components results the function of an ecosystem. Even though there is a certain
amount of mangroves in Sri Lanka, studies on environmental interaction and
biodiversity of mangrove crabs are almost rare.
Therefore, the objective of the present study is to investigate the biodiversity and
environmental interaction of mangrove crabs in the Kadolkele mangrove. The
research was conducted at Kadolkele, which is located adjacent to the Negombo
lagoon in the west coast of Sri Lanka. Data were collected from a part of Kadolkele
mangrove using random transects. The data on crab diversity and abundance. Soil
salinity, soil pH, soil carbon, soil moisture, soil temperature, ambient temperature and
floral species of mangrove were collected.
The study succeeded in identifying six crab species in the study area of Kadolkele
mangrove of which five were identified up to species level. The identified species
were Episesarma versicolo, Sesarma smithii, Sesarma guttatum, Metopograpsus
thukuhar and Metopograpsus messor. According to the literature this is the first
record of Metopograpslls thukuhar in Sri Lanka. The distribution pattern of crabs
varied significantly with the soil salinity and soil moisture content (p = 0.05). Each
environmental factor showed different correlation to each species. Metopograpsus
thukuhar and Sesarma smithii species were distributed throughout the mangrove
while Metopograpsus messor and undefined species were occurred close to the
mangrove water level. Episesarma versicolor and Sesarma guttatum species were
mainly concentrated to land side. Seven species of mangrove flora were identified and
clear zonation was observed. The identified species were Avicennia marina,
Bruguiera gymnorhiza. Aegiceras corniculatum, Lumnitzera racemosa, Acanthus
ilicfolius, Sonneratia caseolaris and Rhizophora mucronata.
