The effect of rearing temperature in larval development of pejerrey, Odontesthes bonariensis: morphological indicators of development

Abstract

It is well known that in pejerrey water temperature not only affects growth rates but also directs the sexual differentiation process. This fact rise the question of how different the development of pejerrey larvae of the same age is when reared at different temperatures. A description of developmental stages for the embryonic and larval periods of the pejerrey, Odontesthes bonariensis, and the influence of rearing temperature on larval development are presented. Then, larval development was studied at three rearing temperatures, and changes in general morphology, fin morphology, and caudal fin structure have been taken into consideration within the thermal range involved in the temperature sex determination of this species. Fin fold reabsorption, caudal fin formation, and body shape were selected to follow the events leading to the acquisition of the juvenile morphology. The juvenile phenotype was defined when the fin fold was reabsorpted and the caudal fin acquired its definitive homocercal structure. The moment at which the juvenile phenotype was achieved, was evaluated in relation to larval age, size and, shape. The size resulted as the best indicator of development in pejerrey.A temperatura da água não afeta apenas as taxas de crescimento no peixe-rei, mas também direciona o processo de diferenciação sexual. Este fato levanta o questionamento de quão diferente é o desenvolvimento de larvas do peixe-rei da mesma idade quando criadas em temperaturas diferentes. Este trabalho teve como objetivo apresentar uma descrição do de desenvolvimento de embriões e larvas do peixe-rei, Odontesthes bonariensis, e a influência da temperatura de criação no desenvolvimento das larvas. Neste trabalho, o desenvolvimento das larvas foi estudado em três temperaturas diferentes de cultivo. Foram consideradas as alterações ocorridas na morfologia geral, assim como na morfologia e na estrutura da nadadeira caudal dentro da variação termal da temperatura de determinação sexual desta espécie. A taxa de reabsorção da membrana embrionária, a formação da cauda e o formato do corpo foram selecionados para acompanhar os eventos que levam à aquisição da morfologia juvenil. O fenótipo juvenil foi definido quando a nadadeira caudal foi reabsorvida e a cauda adquiriu a estrutura homocerca. O momento no qual o fenótipo juvenil foi atingido, foi avaliado quanto à idade, tamanho e formato da larva, sendo que o tamanho resultou no melhor indicador do desenvolvimento do peixe-rei.

Regulation of somatic growth and gene expression of the GH–IGF system and PRP-PACAP by dietary lipid level in early juveniles of a teleost fish, the pejerrey (Odontesthes bonariensis)

“…In our study, pejerrey at 83 dah showed a total SGR of 4.6 ± 0.1 (diet L10), 4.3 ± 0.1 (L13) and 4.9 ± 0.2 (L21) and a final body length of 25.0 ± 0.5, 24.6 ± 0.6 and 25.5 ± 0.6 mm, respectively. The different results in terms of growth between our study and Chalde et al (2011), which was developed in the same experimental facilities than ours, might be provoked by many factors, including variations in the broodstock origin and the initial size of the fish at hatching, the water temperature (that in our study oscillated between 17 ± 1°C, whereas they kept constant at 17°C), the diet composition and the starting date of the artificial feeding (27 vs. 42 dah). The mentioned studies by Toledo-Cuevas et al (2011) and Chalde et al (2011) do not show the formulations of their experimental diets; therefore, it is possible to speculate that in our study the lack of additional sources of phospholipids to those provided by fishmeal (i.e., soy or marine lecithin) might have been a contributing factor responsible of the lower growth rates exhibited by our fish.…”

“…Previous experiments developed with fish larvae suggest that the incorporation of non-nutritive filler such as cellulose strongly reduces larvae growth (Zambonino-Infante and Cahu 1999). In our experiment, the increase in dietary lipids from 10 to 21% was initially followed by a significant increase of the SGR and SGRL (experimental day 14; 41 dah) and body weight (experimental day 35; 62 dah) in fish fed with the higher lipid content, which slightly decreased at the end of the experimental period (day 56; 83 dah) once the fish had already metamorphosed to early juveniles (Chalde et al 2011). Although the nutritional requirements are specific for every fish species, in European sea bass (Dicentrarchus labrax) the increase in dietary lipid content from 10 to 30% led to a significant increase of the final body weight of the larvae, suggesting that the rapid initial growth rates of fish larvae and fry require high-energy diets (ZamboninoInfante and Cahu 1999).…”

“…In the study by Toledo-Cuevas et al (2011), pejerrey fry showed a global SGR = 6.8 at the end of a 91-day experimental period to finally reach a final body length of 50.04 ± 3.37 mm. Also, in Chalde et al (2011) pejerrey fed with artificial diets since 42 dah reached a final body length of 28.28 ± 1.55 mm at the age of 77 dah, when fish were reared at a constant temperature of 17°C. In our study, pejerrey at 83 dah showed a total SGR of 4.6 ± 0.1 (diet L10), 4.3 ± 0.1 (L13) and 4.9 ± 0.2 (L21) and a final body length of 25.0 ± 0.5, 24.6 ± 0.6 and 25.5 ± 0.6 mm, respectively.…”

Early morphological variation and induction of phenotypic plasticity in Patagonian pejerrey

“…Sund & Falk-Petersen (2005) and Peterson et al (2004) also observed in Anarhichas minor and Gadus morhua that embryos incubated at lower temperature hatched with larger length. Furthermore, water temperature directs the sexual differentiation process in the pejerrey Odontesthes bonariensis (Valenciennes) and affects larval condition and growth rate (Strüssmann & Patiño, 1995;Ito et al, 2005;Chalde et al, 2011).…”

Cambios Morfológicos en la Ontogenia Temprana de Chirostoma riojai

“…Durante el periodo larval entre los 10 y los 30 DDE los cambios de figura también son notorios no solo en la figura evaluada, también por el desarrollo de las aletas dorsales, pélvicas y anal, características que le permite al organismo tener una capacidad mayor de movimiento, conjuntamente con la modificación de la mandíbula y con ello un mejor aprovechamiento de los recursos (Chalde et al, 2011).…”