by Okamoto, Marcelo Hideo

Abstract (Summary)
This work aimed to determine the effects of temperature on eggs and larvae of Brazilian flounder Paralichthys orbignyanus. Eggs were exposed to 14, 17, 20, 23, 26 and 29°C and after hatching, the standard length, the yolk-sac volume and its consumption, the percentage of abnormal larvae and time to starvation at each temperature were registered. Larviculture was done at 17, 20, 23 and 26°C, 500 larvae were transferred to 10 L tanks and fed on rotifer and Artemia sp. nauplii. Mortality was registered daily, and every five days standard length was measured. All statistical analyses were carried out using one-way ANOVA and Tukey?s Test at 95% confidence level. Time to hatch was inversely proportional to the temperature, but the percentage of abnormal larvae was higher at extreme temperatures, decreasing at 20, 23, and 26°C. Standard length at hatching was similar (P>0.05) between 17 and 29°C (1.76 ? 1.81mm), but significantly smaller (P<0.05) at 14°C (1.58mm). The yolk-sac volume was inversely proportional to temperature, except at 14°C, where the volume was smaller than at 17°C. Time to starvation was higher (six days) at 23°C. There was 100% of mortality at 17°C 12 days after hatching, survival was significantly lower (P<0.05) at 20°C (2.1%) when compared to 23°C (11.7%) and 26°C (11.7%). Standard length at metamorphosis wassimilar at 20 and 26°C, 9.29±0.15mm and 9.02±0.11mm respectively, but significantly larger than at 23°C 8.23±0.07mm (P< 0.05). Metamorphose was completed faster at 23 and 26°C (20 days) than at 20°C (35 days). The percentage of abnormal juvenile after metamorphosis was 59% at 26°C, higher than at 20 and 23°C (21 and 17%respectively). The results of this study suggest that eggs and larvae can be reared at 23°C, because despite of smaller growth at this temperature, the survival rate is good and the rate of abnormal larvae is low.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Ronaldo Olivera Cavalli; Ricardo Berteaux Robaldo; Juvencio Luis Osorio Fernandes Pouey; Luís André Nassr de Sampaio

School:Fundação Universidade Federal do Rio Grande

School Location:Brazil

Source Type:Master's Thesis

Keywords:temperature eggs aquaculture larvae Paralichthys orbignyanus


Date of Publication:06/30/2004

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