COLONIZATION OF HYDROELECTRIC RESERVOIRS IN BRAZIL BY FRESHWATER SPONGES, WITH SPECIAL ATTENTION ON ITAIPU

摘要

The news that workers reported itchiness when cleaning fish breeding cages in the Itaipu Binational Hydroelectric Reservoir led the authors to carry out a survey to detect sponges along all the Brazilian bank of the Lake. The proposal was based on existing knowledge, the occupation of both lakes and the hydroelectric power station (HPS) turbines in Brazil by this fauna, and of dermatological irritation and eye pathologies caused by the siliceous spicules from sponges in Amazonian rivers. The survey carried out along the bank-side vegetation, the fish breeding cages and their buoying devices, and sampled sediments revealed sponge incrustation on the fish breeding cages, the bank-side vegetation and on rocky substrates, as well as loose spicules in the sediments, with specificity in relation to the preferred sub-rnstrates. Hence, Radiospongilla amazonensis was only detected on the leaves and stalks o/Egeria sp., Polygonum hydropiperoides and roots of Oxycarium cubensis; and Corvospongilla seckti on the walls of the breeding cages; Trochospongilla repens on the rigid surface of polyethylene floats of some of the cages and, as with Oncosclera navicella and Potamophloios guairensis n. sp. on rocky substrates at the head of the Lake. The sponges were seen to compete for substrate with the exotic bivalve Limnoperna fortunei. The results are compared with those reported for other HPS reservoirs in Brazil. The possibility of carrying out freshwater spongiculture experiments in these reservoirs, and the prevention of the effects of human contact with the spicules, are considered.