Diversity of Freshwater Shrimps (Atyidae and Palaemonidae) along the Continnum of Urabaru Stream, Kikaijima Island, Japan

Diversity of freshwater shrimps was investigated along the continuum of Urabaru stream Kikaijima Island, Japan. Total five stations were sampled from May 2007 to December 2008 in Urabaru stream. Total twelve species including seven Atyid and five Palaemonid shrimps were observed during the study. Macrobrachium grandimanus and Atypsis spinipes are reported for first time in a stream of Kikaijima Island. Macrobrachium japonicus, Macrobrachium lar and Caridina typus bserved at all five stations. Higher Margalef diversity was recorded at stations 4 and 5 and lower at Stations 1, 2 and 3. Cluster analysis recorded higher similarity between Stations 4 and 5 at one cluster and Sations 1, 2 and 3 at other. Our results suggesting higher diversities at stations located near river mouth (4 and 5) and gradulay lower diversities at the stations located away from the river mouth (1, 2 and 3). Diversity of all the stations located along the continuum of Urabaru stream is mainly effected by amphidromy of the shrimps.