Biodiversity of decapod crustaceans in the estuarine floodplain around the city of Belém (Pará) in Brazilian Amazonia

the present study focused on the decapod fauna of the fluvial-estuarine environment of the guajará bay, in the brazilian state of pará, where specimens were collected monthly from six sites, from may 2006 to april 2007. a total of 6,793 specimens were captured, belonging to 11 species of crab and shrimp: eight palaemonids - macrobrachium amazonicum (heller, 1862), macrobrachium surinamicum holthuis, 1948, macrobrachium carcinus (linnaeus, 1758), macrobrachium rosenbergii (de man, 1879), macrobrachium spp. 1-4 -, one portunid - callinectes bocourti a. milne-edwards, 1879 -, and two trichodactylids - sylviocarcinus devileii h. milne-edwards, 1853 and sylviocarcinus pictus (milne-edwards, 1853). while no significant differences were found in the ecological indices of diversity with respect to season, site, or trap size, a tendency for increased abundance and species richness was found during the dry season (august-november), in particular at some sites, apparently reflecting the influence of the estuary's saline wedge.