Influência de temperatura nos parâmetros reprodutivos e na alimentação de larvas de Lophiosilurus alexandri

Abstract

The objectives of this thesis were to evaluate the manipulation effect of temperature on reproduction, metabolic profile and larval feeding of Lophiosilurus alexandri. For the reproduction experiment, four males and 12 females were used. From week 1 to 22, the water temperature was maintained at 24.4±1.0 °C. After week 22, the water temperature was elevated and maintained at 29.0±1.1 °C until week 44. For the second experiment, the metabolomic approach for Nuclear Magnetic Resonance was used in the evaluation of the metabolic responses in the serum of the reproducers, submitted to the conditions described above. In the third experiment, evaluations were made on the ingestion and digestion of artemia nauplii by L. alexandri larvae at different temperatures: 23, 26, 29 and 32 °C; different ages: 8, 13, 18 and 23 days after hatching; different times 5, 15, 30, 45, 60, 120, 180 and 300 minutes after feeding. Spawning weight, number of eggs/spawn, and hatching rate were satisfactory and ranged from 27.5-127.5g, 1209-5183 and 83-89%, respectively, during breeding. Hematocrit, leukocytes and glucose were not influenced by the increase in temperature (P<0.05). No variation in 17β-estradiol was evidenced as a function of the temperatures evaluated (P>0.05). Reproductive behavior for L. alexandri has been reported, including court and parental care. Lower values of valine, creatine/phosphocreatine and polyunsaturated fatty acids were verified at 24 °C. After elevation of temperature, there was an increase in the glycerol unit of the fatty acids that make up the lipid fraction of lipoproteins and total cholesterol. For larvae, the consumption of artemia, consumption of live weight percentage and digestion rate in L. alexandri larvae were influenced (P<0.01) by temperature, age and time, as well as by the interaction between these three factors. Based on these results it was possible to conclude that adult individuals are able to maintain stable hematological parameters during the elevation of water temperature from 24.4 °C to 29.0 °C and to produce good quality larvae. The predominance of serum lipids was the main metabolic alteration due to the increase in water temperature from 24 to 29 °C. Temperatures of 29 and 32 °C provided the most satisfactory results for larval feeding.