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

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. faxoni typically presented the highest densities.

A checklist for the zooplankton of the Middle Xingu – an Amazon River system / Diversidade zooplanctônica do médio Rio Xingu – bacia amazônica

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.

Levantamentos realizados em dois lagos e no canal principal do médio Xingu objetivaram a listar a diversidade do zooplâncton. De um total de 175 táxons, 141 foram rotíferos, 20 cladóceros e 5 copépodes. As corredeiras foram os ambientes mais diversos com 124 táxons, enquanto que no Lago da Ilha Grande se registraram somente setenta táxons. Destaca-se a ocorrência de grupos de hábito não planctônico na coluna d’água do rio que indica o efeito perturbador da correnteza.