<b>Relationship between environmental factors and fish eggs and larvae distribution in the Ivinhema River basin, Mato Grosso do Sul State, Brazil</b> - DOI: 10.4025/actascibiolsci.v28i2.1027

Abstract

The spatial and temporal distribution of fish eggs and larvae in the Ivinhema River Basin was analyzed. The aim was to determine the spawning areas and their relationship to environmental factors. Monthly collections were done from September, 1994, to February, 1995, in four sites: one in the Ivinhema River and three in different tributaries. Conic-cylindrical plankton net with 0.5 mm, coupled with a flow meter was used, and the samples were preserved in formol 4%. The abundance was standardized for 10 m³. Data related to water temperature, dissolved oxygen, pH, electric conductivity, and rainfall were also collected. Principal Components Analysis determined the correlation between the environmental variables and the ichthyoplankton density along each river stretch. 23,325 eggs and 16,012 larvae were collected. The density was higher during the rainy period. The spawning period coincided with high precipitation level and temperature (October to December), with higher densities on the collect stations of Dourados and Vacaria rivers, with relatively basic pH and low electric conductivity.