Evaluacion del potencial reproductivo del chorito (Mytilus chilensis) de dos poblaciones naturales sometidas a diferentes temperaturas de acondicionamiento

Abstract

RESUMEN.Mytilus chilensis tiene ciclos reproductivos que varían latitudinalmente. Presenta reducida diferenciación genética y morfológica debido a un gran potencial de dispersión. Se acondicionaron reproductores de bahía Yaldad (Chiloé) y bahía Zenteno (Punta Arenas) a 9 ± 0,5°C y 15 ± 0,5ºC, alimentados con dieta (1:1) de Isochrysis galbana y Chaetoceros neogracile. Se espera dilucidar si el acondicionamiento a diferentes temperaturas produce variaciones en el potencial reproductivo de las poblaciones. El menor desarrollo gonadal se produjo en los reproductores acondicionados a 9ºC, mientras que el mayor se produjo en los reproductores acondicionados a 15ºC provenientes de Chiloé. La fecundidad de los reproductores de Yaldad fue mayor que los de Zenteno. El diámetro de los ovocitos fue mayor en los reproductores de Zenteno y en ambas poblaciones fue mayor a 9ºC. Ni el porcentaje de huevos fecundados ni el porcentaje de eclosión de larvas D mostraron diferencias significativas entre las poblaciones a ninguna de las temperaturas de acondicionamiento. De acuerdo con estos resultados, no se logra establecer diferencias en el potencial reproductivo en las poblaciones y bajo las condiciones de este estudio. Palabras clave: acondicionamiento, mitílidos, potencial reproductivo, temperatura, índice de condición, Chile. Assessment of the reproductive potential of the mussel (Mytilus chilensis) from two natural populations subjected to different conditioning temperaturesABSTRACT. The reproductive cycles of Mytilus chilensis vary latitudinally. This species has reduced genetic and morphological differentiation due to its high potential for dispersal. Broodstocks from Yaldad Bay (Chiloé) and Zenteno Bay (Punta Arenas) were conditioned at 9 ± 0.5°C and 15 ± 0.5°C, and were fed a diet (1:1) of Isochrysis galbana and Chaetoceros neogracile. We expected to determine whether conditioning at different temperatures produces changes in the reproductive potential of the populations. Gonadal development was lowest in the broodstocks conditioned at 9ºC, and highest in those conditioned at 15°C, from Chiloé. Fertility was greater in broodstocks from Yaldad than in those from Zenteno. Oocyte diameter was greater in broodstocks from Zenteno, and both populations showed larger diameters at 9ºC. Neither the percentage of fertilized eggs nor the percentage of larvae hatching differed significantly between populations at either conditioning temperature. Therefore, it was not possible to establish differences in the reproductive potential of the populations under the conditions studied herein.

Transgenerational Effects of pCO2-Driven Ocean Acidification on Adult Mussels Mytilus chilensis Modulate Physiological Response to Multiple Stressors in Larvae

“…Our results demonstrated that oocyte size in both p CO 2 levels were smaller (∼2 μm) than reported by Lagos et al (2012b) for M. chilensis but within the range reported by Ockelmann (1965) for a number of bivalves. No effect in oocyte size from broodstock exposed to high p CO 2 levels was observed.…”

“…Our experimental approach considered an initial spawning of adult mussels in order to homogenize the state of gonadal development prior to reproductive conditioning under two OA scenarios (550–1200 p CO 2 ) and otherwise optimal conditions of food supply and temperature. While previous experimental studies in M. chilensis have reported conditioning periods of up to 81 days at 15°C ( Lagos et al, 2012b ), we extended this period to ca. 4 months to be consistent with other transgenerational OA experiments in mollusks ( Parker et al, 2012 , 2017a ; Fitzer et al, 2014 ; Griffith and Gobler, 2017 ; Zhao et al, 2017 ).…”

“…Mussels were kept in eight 25 L tanks with five specimens each (mean density = 0.2 ind L -1 ). Temperature was increased to 15°C to promote gonadal development ( Lagos et al, 2012b ). After 16 weeks of incubation at these nominal p CO 2 levels, each group of adult mussels was induced to spawn maintaining the same low and high p CO 2 conditions.…”

Linking social preferences and ocean acidification impacts in mussel aquaculture

“…However, for adult individuals the exposure time was shorter, since adult mussels considered in our study were at pre-spawning stage (50 mm shell length, Lagos et al . 58 ). It is well known that after that size, adult mussels change their energy expenditure destined mainly to the reproduction phase 59 .…”