Efecto de seis dietas en el crecimiento y supervivencia de poslarvas de abulón rojo (Haliotis rufescens) y su híbrido (H. rufescens ♀ × H. fulgens ♂)

One of the main bottlenecks in abalone aquaculture is maintaining individuals during the weaning stage, when the natural diet changes from diatoms (postlarvae) to macroalgae (juvenile). During this period, abalone pass through profound morphological and physiological changes, which suitable nutrient requirements must sustain. An inadequate diet can result in adverse effects such as late metamorphosis, starvation, slow growth and even death during this phase. Two strategies have been proposed to increase the growth and survival rates of weaning abalone: (i) extending feeding with benthic diatoms and (ii) abalone hybridization via interspecific crosses. To evaluate the efficiency of the two strategies, we assessed the growth and survival rates of postlarvae of pure red abalone (Haliotis rufescens) and a hybrid obtained by crossing red abalone females with green abalone (H. fulgens) males. Both crosses were supplied with six different diets consisting of either one macroalgae mono-diet (Macrocystis pyrifera or Ulva ohnoi) or a mixture with Navicula incerta. Overall, cross-specific diets achieved better growth rates, suggesting that each cross may need specific food items (nutrients) during weaning. Moreover, pure red abalone generally showed the highest growth rates, while the hybrid abalone showed the highest survival rates with most tested diets. Hence, hybrids appear to be better at withstanding stressful conditions, and their use in aquaculture could reduce losses and increase commercial production.   Uno de los principales cuellos de botella en la acuicultura de abulón es el mantenimiento de los individuos durante la fase de destete, cuando la dieta natural cambia de diatomeas (postlarvas) a macroalgas (juveniles). Durante este período, el abulón pasa por profundos cambios morfológicos y fisiológicos, que deben ser sostenidos por una alimentación adecuada. Una dieta inadecuada puede provocar efectos adversos como: metamorfosis tardía, inanición, crecimiento lento e incluso la muerte durante esta fase. Por ello, se han propuesto dos estrategias para aumentar las tasas de crecimiento y supervivencia del abulón durante la fase de destete: (i) ampliar el período de alimentación con diatomeas bentónicas y (ii) la hibridación de abulones mediante cruces interespecíficos. Para determinar la eficacia de ambas estrategias, se evaluaron las tasas de crecimiento y supervivencia de postlarvas de abulón rojo puro (Haliotis rufescens) y de un híbrido obtenido mediante el cruce de hembras de abulón rojo y machos de abulón azul (H. fulgens). A ambos cruces se les suministraron seis dietas diferentes consistentes en una mono dieta de macroalgas (Macrocystis pyrifera, Ulva ohnoi) o en una mezcla con Navicula incerta. En general, con las dietas específicas para cada cruce se obtuvieron mejores tasas de crecimiento, lo que sugiere que cada cruce requiere alimentos (nutrientes) específicos durante el destete. Además, el abulón rojo puro mostró en general las tasas de crecimiento más altas, mientras que en el abulón híbrido se obtuvieron las mayores tasas de supervivencia con la mayoría de las dietas probadas. Por lo que los híbridos parecen soportar mejor las condiciones de estrés, y su uso en la acuicultura podría ayudar a reducir las pérdidas y aumentar su producción comercial

Understanding the population structure and reproductive behavior of hatchery-produced yellowtail kingfish (Seriola lalandi)

The yellowtail kingfish (Seriola lalandi) is a marine endemic fish, and a key species in the national programme for the diversification of Chilean aquaculture. Since it has been recently developed from wild fish, the biology of this species under production is to a large extent unknown. For example, the structure of the different populations used to create the national breeding programme is not well characterised. Moreover, due to the fact that it is not possible to perform stripping of broodstock in yellowtail kingfish, the genetic contributions of individuals are affected by the reproductive behaviour of this species. To increase our knowledge of the biology of this species under aquaculture conditions, the objectives of this study were: (i) to identify the population structures of wild and commercial populations of yellowtail kingfish obtained from different fisheries off the Chilean coast, and compare these to those of Mexican and Australian specimens and (ii) to study the reproductive behaviour of commercial yellowtail kingfish broodstock through paternity testing, to estimate the genetic contributions of individuals throughout the artificial spawning season in captivity. We used a set of 12 highly informative microsatellite markers optimised for paternity testing. The analysis of the population structure showed at least two clusters of yellowtail kingfish, including a single metapopulation from Chile and Australia (possibly explained by the migratory behaviour of this species in the Pacific Ocean), and the other from Mexico (which is most likely composed of California yellowtail, S. dorsalis). Some degree of admixture, albeit small, was observed between the populations from Mexico and Australia. Paternity analysis showed that the average ratio (male/female) contributing in a spawning event was 2.6, confirming the spawning behaviour observed in other species in this genus. Additionally, we observed that males participated in matings regularly during the whole spawning season. Using the results of this research, we recommend modifying the current implementation of yellowtail kingfish breeding programmes to reduce the effects of random genetic drift. This can be achieved by managing the genetic contributions of broodstock in a two-step breeding programme. This study provides useful genetic information for the long-term development and management of the Chilean yellowtail kingfish industry, which involves a species of high importance for the diversification of Chilean aquaculture.CORFO, at the Ministerio de Economia, Fomento y Turismo: PDACH-CORFO 09PDAC-7020, PTEC-CORFO 15PTEC-45861 FONDEF IDEA en dos etapas from ANID at the Ministerio de Ciencia, Tecnologia, Conocimiento e Innovacion, of the Chilean Government: 14-1012

Growth, nutrient uptake and proximate composition of Rhodomonas sp. cultured using f/2 medium and agricultural fertilizers

We determined the growth, nutrient (PO43–, NO3–, NH4+) uptake and proximate composition of Rhodomonas sp. cultured during seven days in batch culture using f/2 medium and agricultural fertilizers. The growth rate was similar with both media (µ = 0.37 and 0.38 day–1). Protein content in Rhodomonas sp. cultured with f/2 medium was higher than with agricultural fertilizers (10.7 and 8.96 pg cell–1, respectively). Carbohydrate and lipid contents decreased during the exponential growth phase and there were no significant differences (P = 0.027 and 0.08, respectively) between both experiments. Carbohydrate content was higher during the slow growth phase in cultures using f/2 medium, whereas lipid content showed little variation during the slow growth phase, but was higher in cells cultured using agricultural fertilizers. During the first five days, total phosphate uptake by Rhodomonas sp. was 39.9 µM (94.3%) in the f/2 medium and 40 µM (99%) in the agricultural fertilizer medium. A total of 667.3 µM of nitrate (72.2%) was consumed during the first four days in the f/2 medium, whereas in the agricultural fertilizer medium formulated with ammonium nitrate, ammonium uptake (418.1 µM, 78.7%) in the first three days was higher than nitrate uptake (37.7 µM, 7.3%); however, when ammonium concentration decreased to 1.83 µM, the nitrate uptake increased. In conclusion, the cellular quantity and quality of Rhodomonas sp. was similar when both media were used and agricultural fertilizers can be used in marine aquaculture programs

Genoma mitocondrial completo del lenguado de California, Paralichthys californicus

El lenguado de California, Paralichthys californicus, es una especie de pez plano con un alto valor econónico debido a su tamaño y a la calidad de su carne. En este trabajo se presenta el genoma mitocondrial completo de P. californicus. Se extrajo ADN total de tejido muscular y se secuenció utilizando la plataforma Illumina. Las lecturas obtenidas se limpiaron, se recortaron, se ensamblaron de novo y se anotaron. El mitogenoma del lenguado de California tiene una logitud de 16,858 pb (número de acceso del GenBank: MT859134) y contiene 13 genes codificadores de proteínas, 22 ARNt, 2 ARNr y la región control. El mitogenoma de P. californicus fue más similar al de Paralichthys olivaceus que a mitogenomas de otros peces planos, en concordancia con su distribución geográfica. La información aquí presentada incrementa el conocimiento del lenguado de California, el cual no solo es una especie de importancia económica, sino también un recurso socioeconómico relevante para la pesquería y la acuicultura de California, EUA, y de Baja California, México

The effects of depth and diet on red abalone growth and survival in cage mariculture at San Jeronimo Island, Baja California, Mexico

In recent decades, global abalone aquaculture has significantly increased, while wild abalone fishery landings have decreased drastically, shifting production from fishing to farming. In California (USA) and Baja California (Mexico), overfishing and climate changelinked diseases are thought to be responsible for mass mortalities and significant declines in abalone fisheries landings. Conservation aquaculture is an option for enhancing abalone populations through captive propagation and cage mariculture with subsequent restockings into the wild. To test, inform, and promote innovative sustainable seafood production strategies in the Northeastern Pacific, we designed an experimental mariculture system at San Jeronimo Island, Baja California. We explored the feasibility of rearing juvenile red abalone, Haliotis rufescens, in a near-shore mariculture cage-based production system to supply individuals for local restoration programs. We tested the effects of 2 different depths, surface and bottom (5 m), and 3 macroalgal diets (Macrocystis pyrifera, Eisenia arborea, and a mixed diet of Pelagophycus porra with M. pyrifera) on the survival and growth of juvenile red abalone (32 ± 3.33 mm in shell length) inside cages attached to a long-line system. Over the 90-d experiment, survival was 99% for the surface treatment and 95% for the bottom treatment. Mean daily increment in shell length was 93 ± 12 µm·d–1 in surface cages and 82 ± 13 µm·d–1 in bottom cages. Depth did not affect growth or survival. Growth was highest using the E. arborea diet (99 ± 7 µm·d–1) but not significantly different from the M. pyrifera and mixed diets (88 ± 10 and 74 ± 13 µm·d–1, respectively). High survivorship and growth indicate that San Jeronimo Island can support cage-based mariculture of red abalone and that this strategy may be a useful tool in developing climate-resilient abalone restoration solutions aimed at bolstering seafood production

Individual Pattern Response to CO₂-Induced Acidification Stress in <i>Haliotis rufescens</i> Suggests Stage-Specific Acclimatization during Its Early Life History

The red abalone Haliotis rufescens is a pivotal marine resource in the context of worldwide abalone aquaculture. However, the species has been listed as critically endangered partly because of the life-history massive mortalities associated with habitat climate changes, including short- and long-term ocean acidification. Because abalone survival depends on its early life history success, figuring out its vulnerability to acidification is the first step to establishing culture management strategies. In the present study, red abalone embryos were reared under long-term CO2-induced acidification (pH 7.8 and 7.6) and evaluated. The impairment prevalence was assessed during their larval stages, considering the developmental success, growth and calcification. The result in the stage-specific disturbance suggests that the body abilities evaluated are at the expense of their development stages, of which the critical threshold is found under −0.4 pH units. Finally, the settlement was short-term stressed, displaying the opposite to that observed in the long-term acidification. Thus, the early life history interacts through multiple pathways that may also depend on the acidification challenge (i.e., short or long term). Understanding the tolerance limits and pathways of the stress response provides valuable insights for exploring the vulnerability of H. rufescens to ocean acidification

GENOMIC INTEGRITY EVALUATION IN SPERM OF CHOROMYTILUS CHORUS (MOLINA, 1782) BY COMET ASSAY

The comet assays or single cell gel electrophoresis is a simple, rapid, relatively inexpensive and very sensitive method that has been recently widely used to evaluate genomic integrity (or DNA damage) in aquatic animals exposed to diverse physical and chemical agents. However, the accuracy to evaluate comets assay has been the major obstacle in order to determine specific damage undergone cellular stress. The aim of this study was to evaluate DNA fragmentation in sperm cells based ill fluorescence image analysis. The Species used was the giant mussel Choromytilus chorus. The in vitro experiments were carried out through oxidative stress with five hydrogen peroxide concentrations (0, 50 100, 500 and 1000 mu M). To evaluate DNA damage two groups of parameters were used: (1) Morphological comet parameters as tail length, nuclear diameter (head) and tail moment, and (2) Quantification of DNA strand breaks grade by fluorescence image analysis. The sperm DNA damage was possitively correlated with the morphological parameters, as they were exposed to an increasing dose range of H2O2 and negatively correlated with nuclear diameter. Additionally, fluorescence analysis showed that fragment sizes and the fluorescence intensity Could be identified and related the level of DNA damage independently the intercellular variation of DNA strand breaks. The large fragment sizes decrease with H2O2 doses, while medium and small fragments increase in treatments with highest peroxide concentration. This study supported future research to examine comet assay conjugated with molecular approaches, especially in reference to integrate FISH to evaluate if the DNA fragmentation includes specific genes.CONACYT-Mexico 117673 FONDEF D05i10246 y D06i 102

Genomic DNA variation confirmed Seriola lalandi comprises three different populations in the Pacific, but with recent divergence

Captive breeding programs and aquaculture production have commenced worldwide for the globally distributed yellowtail kingfish (Seriola lalandi), and captive bred fingerlings are being shipped from the Southern Hemisphere to be farmed in the Northern Hemisphere. It was recently proposed that Pacific S. lalandi comprise at least three distinct species that diverged more than 2 million years ago. Here, we tested the hypothesis of different "species" in the Pacific using novel genomic data (namely single nucleotide polymorphisms and diversity array technology markers), as well as mtDNA and DNA microsatellite variation. These new data support the hypothesis of population subdivision between the Northeast Pacific, Northwest Pacific and South Pacific, and genetic divergence indicates restriction to the gene flow between hemispheres. However, our estimates of maximum mtDNA and nuclear DNA divergences of 2.43% and 0.67%, respectively, were within the ranges more commonly observed for populations within species than species within genera. Accordingly our data support the more traditional view that S. lalandi in the Pacific comprises three distinct populations rather than the subdivisions into several species