ความชุกชุมและการแพร่กระจายของปู บริเวณทะเลสาบสงขลาตอนนอก

Abstract

This study aims to investigate the species diversity, abundance and distribution of crabs inhabiting in outer Songkhla lake and the association of habitat type, some environmental factors and the crab species occurrence. Crab samples and environmental factors were collected every trimester for 1 year from November 2015 to August 2016. The habitats were classified into 5 habitats types including mangrove forest, inner lake channel, outer lake channel, mid lake and inner lake. The study revealed a total of 2,393 crabs, comprising 28 species 12 family. The most common species was Portunus pelagicus (Linnaeus, 1758), 1,344 individuals (56%), followed by Charybdis (Charybdis) affinis (Dana, 1852), 377 individuals (16%) and Varuna yui (Hwang & Takeda, 1986) with 375 individuals (16%). The crab species diversity and abundance show seasonal variation which in summer, 1,747 individuals from 11 families and 25 species were recorded and in rainy season, 646 individuals from 8 families and 15 species were found. Crab distribution did not show significant relation with particular environmental factors but showed different pattern by different habitat types. Scylla paramamosain (Estampador, 1950) and Scylla olivacea (Herbst, 1796) were limited to Mangrove area and P. pelagicus and C. affinis were common in channel stations. Moreover, 18 species are reported for the first time from the outer Songkhla lake; namely Macrophthalmus (Venitus) latreillei (Desmarest, 1822), Scylla paramamosain (Estampador, 1950), Philyra Alcocki (Kemp, 1915) and Philyra sexangula (Alcock, 1896), Neoxenophthalmus obscurus (Henderson, 1893), Scylla olivacea (Herbst, 1796), Parapanope euagora (De Man, 1895), Charybdis hellerii (A.Milne-Edwards, 1861), Dorippoides facchino (Herbst, 1785), Tritodynamia sp., Charybdis vadorum (Alcock, 1899), Charybdis anisodon (De Haan, 1850), Thalamita sima (H. Milne Edwards, 1834), Pilumnus sp., Xiphonectes hastatoides (Fabricius, 1798), Podophthalmus vigil (Fabricius, 1798) and Majidae sp.