Qualidade da água e estudo do zooplâncton da estação de piscicultura de Castanhal, Pará.

Abstract

Fishponds are artificial systems that sutfer external and internal influence that GO to act in its rich planktonic community and existing the physical and chemical factors in the aquatic ecosystem. However, exist a lack of limnological studies in fishponds of the Pará State. in this direction, it was developed work in station of Castanitai's fisheuiure with the objectivewas developed to list the species of zooplankton, to calculate the wealth, diversity and equitabilidity between the organisms and to evaluate the water quality in the fisponds. They were accomplished collections during six months in six tanks and ponds, of the station, to do the analyses of temperature, dissolved oxygen, při,conductivity, dissolved total solids, beyoud samping for quaniative and qualitative determination of zooplankton. The biggest temperature was registered in the march month. The oxygen averages thay werebeen above of 6,0 mg/L and pH varied of basic slightly acid one. The condutivicty varied of 8,5 to 25,3 uS/cm, being below of the recommended one for the culture. To the whole they were 80 had been all identified tax, being ő0 of Rotifera, two of Frotozoa, one of Ciophora, 17 of Auopoda, being two of the Insecta Class, 14 of Branchiopoda Class and one of Copepoda Subclass. In density mophora, terms, the great pond IF detached, being represented dominant for rotifers. In occurrence frequency terms the nauplii If had detached among copepods, Polyarthra vulgaris, among rotifers and Macrothrix superaculeata, among Cladocera. Station four had the biggest equitabiiidity, demonsirating bigger uniformity of species. The diversity varied between one and three, being inside of the band considered good for the fishculture. In this work, the limnological variable hadn't varied signiticantly and were inside of the band recommended for the culture systems, except the conductivity that was very low. The biggest wealth of species and dominance of rotifers allowed to consider them as the group most imporiant in the Station; copepods and ciadocers, for being organisms of so greater, had probably been more susceptible to the visual prerestitution for tish.