Distribution of Tanaids in Pulicat

Tanaids constitute an important component of coastal communities, as they found in wide variety of marine and brackish water habitats. They are good micro scavengers, eating detritus and food particles thereby proliferate in abundance and in turn act as an excellent food resource for higher trophic level including significant point source of food for fishes, crustaceans and benthic organisms of commercial and aesthetic value. A total of seven tanaids were recorded from suborder Apseudomorpha represented by four families in Pulicat coastal lake. Among, two species namely Apseudes gymnophobia (Pagurapseudopsis gymnophobia) and Apseudes chilikensis were recorded from family Apseudidae. Three species namely Halmyrapseudes killaiyensis, Saltipedis achondroplasia and Pakistanapseudes sp. A were recorded from family Parapseudidae. Other two species Apseudomorpha sp. A from family Metapseudidae and Kalliapseudes sp from family Kalliapseudidae. Among the seven species, three species namely Apseudes gymnophobia, Apseudes chilkensis and Halmyrapseudes killaiyensis were found in all twenty stations. Saltipedis achondroplasia represented in 14 stations. Pakistanapseudes sp. A represented in 8 stations. Apseudomorpha sp. A and Kalliapseudes sp were found in seven and five stations respectively. Stations such as St.1, St.6, St.7, St.17 and St.20 recorded with six species. St.2, St.10, St.11, St.16, St.18 and St.19 were recorded with five species. St.3, St.5, St.8, St.9, St.12, St.13 and St.14 were observed with four species and St.4 and St.15 noticed to have three species. Among the seven species, the most dominant one was Apseudes gymnophobia (31%) followed by Halmyrapseudes killaiyensis (28%), Apseudes chilkensis (24%), Saltipedis achondroplasia (10 %), Pakistanapseudes  and Apseudomorpha (3 % each) and Kalliapseudes sp (1 %). The population density ranged from 38 no/sq. m to 399 no/ sq. m with mean population density of 623 no/ sq. m. The diversity of the tanaids population varied from 1.109 to 1.384. Evenness of the tanaids differentiated from 0.8 to 1. Species richness deviated from 0.54 to 0.96. Current study on tanaidacea perform key ecological role in the coastal lake ecosystem. The spatial and temporal distribution of tanaids are strongly influenced by physico-chemical parameters, seasons, substratum and its characters.