We evaluated the effect of light intensity on survival rate and zootechnical performance in matrinxã larvae (Brycon amazonicus) that is an important species for fish farming in the Amazon region. For this, the larvae were submitted to three experimental stages: Stage I-10-72 hr after hatching (HAH), Stage II-72-168 HAH and Stage III-168-288 HAH. The animals were submitted to three treatments of different light intensities: low (±20 lx), intermediate (±200 lx) and high (±2,000 lx). The low light intensity increased the survival rate in 24, 48, 72, 120, 168 and 288 HAH. The size of the animals was homogeneous in 72 and 168 HAH in the low and intermediate treatments. The high light intensity increased the zootechnical parameters in 288 HAH. We suggest the use of low light intensity in the initial periods of observation (24 and 48 HAH) to reduce aggressiveness and increase the survival and homogeneity of the animals. On the other hand, it is possible to suggest an increase in the light intensity in the final period of observation (288 HAH), as the increase in intensity stimulated growth and affected the survival rate of the matrinxã larvae.

No abstract

No abstract

Mit 1 Abbildung In haltsii bersieht Es wird die Transmission fiir Impulse verechiedener Form (GauS-, Lorentz-und Rechteckimpuls) bei Durchlauf durch eine Absorberkiivette angegeben. Die Atome dea Mediums werden als Zwei-Niveau-S teme angenommen. Die Anderung der Besetzun im unteren Niveau wird in einer ersten Niicrung beriicksichtigt, so daS die erhaltenen Er effnisse nur fiir hinreichend schwache Impulse gelten. Die Transmission ist im hier betraohteten #all der (schwach) nichtlinearen Abso tion u.8. von der Impulsform und der longitudinalen Relaxationszeit des Absorbers abhangig. %it Hilfe der berechneten Kurven liifit sich fur die drei angegebenen Impulstypen bei Kenntnis der Transmission die Relaxationszeit bestimmen. AbstraetFor Gaussian, Lorentzian, and square pulses passing through an absorbing medium the transmission is calculated. The atoms in the medium are regarded as two-level-systems. The pulses are assumed to be so weak that the change of population in the lower level is small. The transmiasion in our case of (weak) non-linear absorption depends on the shape of the pulse and the longitudinal relaxation time. Knowin the transmission the relaxation time can be determined by means of the oomputed curves of t a e mentioned three typea of pulees.