A checklist for the zooplankton of the Middle Xingu – an Amazon River system

Abstract A zooplankton checklist is presented for the Middle Xingu River, based on surveys conducted at four sites in the main channel and two fluvial lakes. A total of 175 taxa are listed, including 141 rotifers, 20 cladocerans, and five copepods. Rapids presented the greatest species richness, with up to 124 taxa, while Ilha Grande lake had 70 taxa, the lowest number. Non-planktonic benthic larvae were recorded frequently in the samples

Distribution of the Planktonic Shrimp Lucifer (Thompson, 1829) (Decapoda, Sergestoidea) off the Amazon

Lucifer faxoni (BORRADAILE, 1915) and L. typus (EDWARDS, 1837) are species first identified in the neritic and oceanic waters off the Amazon. Samplings were made aboard the vessel “Antares” at 22 stations in July and August, 2001 with a bongo net (500-µm mesh size). Hydrological data were taken simultaneously for comparative purposes. L. faxoni was present at thirteen of the fourteen neritic stations analysed, as well as at five of the eight oceanic stations. L. typus was present at three of the fourteen neritic stations and in one of the eight oceanic stations. The highest density of L. faxoni in the neritic province was 7,000 ind.m–3 (St. 82) and 159 ind.m–3 (St. 75) in the oceanic area. For L. typus, the highest density observed was 41 ind.m–3 (St. 64) in the neritic province. In the oceanic province, the highest single density value was recorded at station 75 (5 ind.m–3). Overall, L. faxonitypically presented the highest densities