Reproductive dynamics of Leporinus obtusidens captured downstream from an important hydropower Station in Brazil

This study evaluated the reproductive dynamics and gonadal morphology of piaparas (Leporinus obtusidens) captured downstream from the Funil Hydroelectric Power Station. The 107 piaparas evaluated were captured monthly from Sep 2006 to Aug 2007. The data were stratified among the seasons to evaluate gonad maturation and the reproductive period was determined by assessing the gonadosomatic index, hepatosomatic index, abdominal fat index (AFI), weight:length ratio, condition factor and sexual proportion. The reproductive period lasted from winter to summer (Jul-Mar) in females and from spring to autumn (Sept-Jun) in males. AFI was high during and after the reproductive period in females and only during the reproductive period in males. The highest HIS values for males and females were obtained in spring and summer (Sept-Mar). The females observed did not spawn and showed follicular atresia. These characteristics suggest that L. obtusidens does not use the study area as a reproductive site and probably migrates for this purpose

Desenvolvimento inicial e estado nutricional de clones de eucalipto no nordeste do Pará Initial growth and nutritional status of Eucalyptus clones in northeast of Para State

O objetivo desta pesquisa foi avaliar o desenvolvimento inicial, nutrição e fertilidade do solo em plantio de clones de eucalipto no nordeste do Pará. Os tratamentos constaram de cinco clones (Eucalyptus grandis x E. urophylla - 03 e 09, E. urophylla x E. camaldulensis - 32, E. grandis x E. pellita - 07 e E. camaldulensis - 11), dispostos em delineamento de blocos ao acaso com quatro repetições. Cinco meses após plantio foram avaliadas a altura e sobrevivência das plantas. Aos 18 meses, além dessas variáveis, foram avaliados o diâmetro à altura do peito (DAP), a fertilidade do solo (profundidades 0-10 e 10-20 cm) e os nutrientes foliares. A altura e o DAP das árvores não variaram entre clones nas épocas de avaliação. Houve diferença na porcentagem de sobrevivência apenas aos 18 meses, sendo do clone 07 a menor média apresentada. Na camada de 0-10 cm foram observados os menores valores de K trocável no solo sob os clones 09 e 07, nas parcelas deste último foram observado também a menor CTC. Na camada de 10-20 cm, o menor valor de N no solo esteve sob o clone 32, enquanto que o K e Ca trocáveis foram encontrados em maiores quantidades sob o clone 03. De maneira geral, foram observadas as maiores concentrações de todos os nutrientes, com exceção do N, nas folhas dos clones 11 e 32. Desta forma, os clones apresentaram respostas nutricionais diferentes na área de estudo, assim como o solo sob cada material genético apresentou valores variados de fertilidade. Essas variações, entretanto, pouco foram observadas no desenvolvimento inicial das árvores.<br>The objective of this research was to determine the initial growth, nutrition and soil fertility of Eucalyptus plantation in Moju, northeast city of Para State, Brazil. The treatments used were five clones (Eucalyptus grandis x E. urophylla - 03 e 09, E. urophylla x E. camaldulensis - 32, E. grandis x E. pellita - 07 e E. camaldulensis - 11), organized in a randomized blocks design with four replications. Five months after planting, the height and survival percentage of plants were measured. At 18 months, besides these variables, diameter, soil fertility at the 0-10 and 10-20 cm depth and plant mineral nutrition were evaluated. The height and diameter did not vary among clones at evaluated times. There was difference in survival percentage just at 18 months, when the 07 clone showed the lower average. At the 0-10 cm soil depth, the lowest K exchangeable was observed under the 09 and 07 clones, the clone 07 also presented the lowest soil CEC. In 10-20 cm depth, the lowest value of N was observed in 32 clone, while the K and Ca were observed in highest levels in 03 clone. In general, higher macro and micronutrients leaves contents were found in the 11 and 32 clones, exception N. The clones presented different nutritional responses over the researched area, as well as the soil fertility under each clone presented varied values. Such variations, however, were little observed in the tree initial growth