Diversity of mangrove crabs in Kadolkele, Negombo eatuary, Sri Lanka

Abstract

The present study was carried out from May 2001 to August 2001 to investigate the diversity, distribution and environmental interactions of mangrove crabs in the Kadolkele mangrove ecosystem associated with the Negombo estuary in the west coast of Sri Lanka. The data on diversity and abundance of crabs, salinity, pH, organic carbon content, moisture and temperature of the soil, ambient air temperature and floral species of mangrove were collected from three 10 m x 50 m belt transects laid perpendicular to the shore. Of the six species of crabs found in the study area, five were identified up to species level. They were Episesarma versicolor, Sesarma smithii, Sesarma guttatum, Metopograpsus thukuhar and Metopograpsus messor. This is the first record of Metopograpsus thukuhar and Sesarma guttatum in Sri Lanka. Diversity of crabs decreased with the increasing distance from the lagoon but the number of crabs present did not vary significantly (p > 0.05). The distribution of the crabs varied with the increasing distance from the lagoon. S. smithii and M. messor were distributed throughout the 50 m distance while M. thukuhar and the unidentified species were restricted to 0-20 m and 0-10 m from the lagoon respectively. E. versicolor and S. guttatum were found towards the landward side (25-50 m). The distribution of S. smithii showed a positive correlation (p < 0.05) with the soil salinity and soil moisture content while M. thukuhar, S. guttatum and E. versicolor showed negative correlations (p < 0.05). All species except E. versicolor showed a positive correlation with soil organic carbon content (p < 0.05). M. thukuhar showed a negative correlation with soil pH while S. guttatum and S. smithii showed a positive correlation (p < 0.05). M. thukuhar and unidentified juvenile crabs were found restricted to Rhizophora/Bruguiera zone, while E. versicolor and S. guttatum were confined to the Avicennia /Lumnitzera zone.

Floral and Faunal Diversity in Sri Lankan Mangrove Forests: A Systematic Review

“…Since there is a lesser number of publications on mangrove faunal diversity, and most of them focus on Negombo while the other coastal districts are left behind, we cannot look at the regional occurrence of fauna and their distribution pattern. In addition, some mangrove faunal studies have ambiguities from the taxonomical perspective [48]. Certain studies have sought to identify and analyze the macrobenthic community in the Negombo estuary, although they could have reported the taxonomical nomenclature up to class and/or order level.…”

Lagoons of Sri Lanka: from the origins to the present

“…However, crab fattening is a domestic fishery industry in the Batticaloa Lagoon. Jayamanne and Jinadasa (1993) studied the biology and economics of the mud crab fishery in the Negombo Lagoon and later Priyadarshani et al (2008) conducted an intensive study in the Kadolkelle area. Some important edible fish species such as sea bass (Lates calcarifer), rabbit fishes (Siganus spp.…”

Population structure and reproductive biology of the crab Sesarma rectum Randall, 1840 (Brachyura, Sesarmidae) in an impacted tropical mangrove in northeast Brazil

“…Many studies have demonstrated the abundance and dominance of the crab families Ocypodidae, Grapsidae, and Sesarmidae in tropical mangroves (e.g., Frusher et al, 1994;Skov et al, 2002;Priyadarshani et al, 2008).…”