Transcriptome analyses of female black tiger shrimps (Penaeus monodon) for reproductive trait using RNA-sequencing approach

The black tiger shrimp (Penaeus monodon) is the widely cultured aquaculture species in Vietnam and worldwide. Production of P. monodon postlarvae still relies on the wild broodstock due to their higher fecundity and larval quality in comparison with the domesticated broodstock. Therefore, the current study applied an RNA-sequencing approach by the Illumina platform to generate the transcriptomic resources for the wild and domesticated females at the previtellogenic stage of ovaries (stage 0). Total clean reads were 20,977,708 for the wild female and 31,185,197 for the domesticated female. De novoassembly was employed to generate 35,870 contigs with an average length of 1,018 bp and N50 length of 1,488 bp. The ratios of contigs possessing significant similarity through annotation across seven databases ranged from 19.74 to 47.77%. Top hit species from BLASTx searches included Hyalella azteca, Cryptotermes secundus, Zootermopsis nevadensis, followed by Penaeus sp.. We identified a total of 5,788 differentially expressed transcripts between the ovaries of wild and domesticated shrimps. The differentially expressed transcripts were further enriched according to the classification terms of Gene Ontology (GO). Results of GO enrichment analysis in the wild female indicated that many genes such as hemolymph clottable, peritrophin, ecdysteroid were up-regulated while the following genes, including serine protease, alpha-L-fucosidase-like, actin, catenin alpha were down-regulated. The current study provides more transcriptomic resources for the reproductive trait in P. monodon. These resources are potentially applied for the improvement of reproduction in the domesticated shrimp.

There and back again: Spatial and temporal variation in the recruitment dynamics of an amphidromous fish

<p>A primary goal of ecology is to identify the factors underlying recruitment variability, and how they may shape population dynamics. Recruitment is driven by the input of new individuals into a population. However, these individuals often show high diversity in phenotypic traits and life histories, and the consequences of this variation are poorly understood. Phenotypic variation is widespread among the early life stages of fish, and this variation may be influenced by events occurring across multiple life stages. While many studies have investigated phenotypic variation and its effect on population dynamics, comparatively few studies use an integrated approach that evaluates patterns and processes across multiple life history stages. Here I focus on a native amphidromous fish, Galaxias maculatus, and I explore patterns and consequences of phenotypic variation during larval stages, migratory stages, and post-settlement stages of this fish. I explore variability in phenotypes and early life history traits of G. maculatus through both space and time. I use metrics derived from body size and otolith-based demographic reconstructions to quantify potentially important early life history traits. I found that cohorts of juvenile fish sampled later in the year were comprised of individuals that were older, smaller, and grew more slowly relative to fish sampled earlier in the year. I also found that two sampled sites (the Hutt River and the Wainuiomata River) showed different temporal trends, despite their close geographical proximity. I then investigated whether phenotype was related to mortality. I used otolith-based traits to characterise larval ‘quality’ for individual fish. I then calculated the average larval quality for discrete cohorts of fish, and used catch-curve analysis to estimate mortality rates for these cohorts. I investigated the overall relationship between quality and mortality, and compared the trend between two sites. My results indicate that phenotype and mortality were not significantly correlated. However, this inference may be limited by low statistical power; the non-significant trends suggest that the relationship might be negative (i.e., larvae of higher quality tend to have lower rates of mortality). This trend is typical of systems where population expansion is limited by food rather than predators. I then investigated whether phenotypic traits in the juvenile cohorts were correlated with traits in adult cohorts. I resampled the focal populations ~6 months after sampling the juvenile stages (i.e., targeting fish from sampled cohorts that had survived to adulthood), and I used data from otoliths to reconstruct life history traits (hatch dates and growth histories). I compared adult life history traits to the traits of discrete juvenile cohorts. My results suggest that fish that survived to adulthood had comparatively slower growth rates (reconstructed for a period of larval/juvenile growth) relative to the sampled juvenile cohorts (where growth rate was estimated for the same period in their life history). I also found that the distributions of hatch dates varied between sites. Fish that survived to adulthood at one site hatched later in the breeding season, while adult stages from the other site had hatch dates that were distributed across the entire breeding season. Both hatch date and growth rate are likely linked to fitness, and their interaction may have influenced patterns of survival to adulthood. These results provide evidence for carry-over effects of larval phenotype on juvenile success Collectively my thesis emphasises the importance of phenotype and life history variability in studies of recruitment. It also highlights the importance of spatial scale, and how biological patterns may differ between geographically close systems. Some of the general inferences from my study may extend to other migratory Galaxiid species, and perhaps more generally, to many species with extensive larval dispersal. Finally, my work highlights potentially important interactions between phenotypes, life histories, and mortality, which can ultimately shape recruitment, and the dynamics of populations.</p>

There and back again: Spatial and temporal variation in the recruitment dynamics of an amphidromous fish

<p>A primary goal of ecology is to identify the factors underlying recruitment variability, and how they may shape population dynamics. Recruitment is driven by the input of new individuals into a population. However, these individuals often show high diversity in phenotypic traits and life histories, and the consequences of this variation are poorly understood. Phenotypic variation is widespread among the early life stages of fish, and this variation may be influenced by events occurring across multiple life stages. While many studies have investigated phenotypic variation and its effect on population dynamics, comparatively few studies use an integrated approach that evaluates patterns and processes across multiple life history stages. Here I focus on a native amphidromous fish, Galaxias maculatus, and I explore patterns and consequences of phenotypic variation during larval stages, migratory stages, and post-settlement stages of this fish. I explore variability in phenotypes and early life history traits of G. maculatus through both space and time. I use metrics derived from body size and otolith-based demographic reconstructions to quantify potentially important early life history traits. I found that cohorts of juvenile fish sampled later in the year were comprised of individuals that were older, smaller, and grew more slowly relative to fish sampled earlier in the year. I also found that two sampled sites (the Hutt River and the Wainuiomata River) showed different temporal trends, despite their close geographical proximity. I then investigated whether phenotype was related to mortality. I used otolith-based traits to characterise larval ‘quality’ for individual fish. I then calculated the average larval quality for discrete cohorts of fish, and used catch-curve analysis to estimate mortality rates for these cohorts. I investigated the overall relationship between quality and mortality, and compared the trend between two sites. My results indicate that phenotype and mortality were not significantly correlated. However, this inference may be limited by low statistical power; the non-significant trends suggest that the relationship might be negative (i.e., larvae of higher quality tend to have lower rates of mortality). This trend is typical of systems where population expansion is limited by food rather than predators. I then investigated whether phenotypic traits in the juvenile cohorts were correlated with traits in adult cohorts. I resampled the focal populations ~6 months after sampling the juvenile stages (i.e., targeting fish from sampled cohorts that had survived to adulthood), and I used data from otoliths to reconstruct life history traits (hatch dates and growth histories). I compared adult life history traits to the traits of discrete juvenile cohorts. My results suggest that fish that survived to adulthood had comparatively slower growth rates (reconstructed for a period of larval/juvenile growth) relative to the sampled juvenile cohorts (where growth rate was estimated for the same period in their life history). I also found that the distributions of hatch dates varied between sites. Fish that survived to adulthood at one site hatched later in the breeding season, while adult stages from the other site had hatch dates that were distributed across the entire breeding season. Both hatch date and growth rate are likely linked to fitness, and their interaction may have influenced patterns of survival to adulthood. These results provide evidence for carry-over effects of larval phenotype on juvenile success Collectively my thesis emphasises the importance of phenotype and life history variability in studies of recruitment. It also highlights the importance of spatial scale, and how biological patterns may differ between geographically close systems. Some of the general inferences from my study may extend to other migratory Galaxiid species, and perhaps more generally, to many species with extensive larval dispersal. Finally, my work highlights potentially important interactions between phenotypes, life histories, and mortality, which can ultimately shape recruitment, and the dynamics of populations.</p>

A Dynamic Energy Budget Approach for the Prediction of Development Times and Variability in Spodoptera frugiperda Rearing

A major challenge in insect rearing is the need to provide certain life cycle stages at a given time for the initiation of experimental trials. The timing of delivery, organism quality, and variability directly affect the outcome of such trials. Development times and intraspecific variability are directly linked to the availability of food and to the ambient temperature. Varying temperature regimes is an approach to adapt development times to fulfill experimental needs without impairment of larval quality. However, current practices of temperature setting may lead to increased variability in terms of development times and the frequency of particular life stages at a given point in time. In this study, we analyzed how resource availability and ambient temperature may affect the larval development of the economically important noctuid species Spodoptera frugiperda by means of dynamic energy budget modeling. More specifically, we analyzed how rearing practices such as raising of temperatures may affect the variability in larval development. Overall, the presented modeling approach provides a support system for decisions that must be made for the timely delivery of larvae and reduction of variability.

Morphology Characteristic, Growth And Survival Rate Of The Early Larval Stages Of Mud Crab, Scylla serrata (Forsskal, 1775) For The Rearing Process

The availability of female adult mature will continuously support mud crab hatchery to produce the best quality of larvae. Bray et al., (1990b) proposed that zoea length can be used as an index of larval quality. Larval quality is dependent on the physiology condition related to the growth and survival rate of several larval development stages (Racotta et al., 2003). The mortality in all development stages was due to the high sensitivity of larvae for the environment changes. Two aquariums and sterilized water were used in all rearing process and larvae of Scylla serrata fed once a day. It was fed by rotifer (Branchionus plicatilis) and Artemia sp on the third and fifth days. The results showed that the eye was a distinguishing characteristic between zoea I and zoea II. Development of zoea I range about 0 (zero) to fourth days and zoea II about fifth to seventh days. Observation of growth for six days indicate an increasing significantly on the fourth to sixth days. The survival rate of Scylla serrata larvae without food holds three days out. Otherwise, larvae that were fed on everyday hold seven days out. ABSTRAKKetersediaan induk yang matang telur secara berkesinambungan akan sangat mendukung usaha pembenihan kepiting bakau dalam menghasilkan larva dengan kualitas yang baik. Bray et al., (1990b) bahwa panjang zoea dapat digunakan sebagai suatu indeks kualitas larva. Selain itu, kualitas larva juga bergantung kepada kondisi fisiologis larva dan berkaitan dengan rata-rata pertumbuhan dan sintasan selama beberapa tahapan larva (Racotta et al., 2003). Seluruh proses pemeliharaan digunakan air steril dengan menggunakan wadah berupa akuarium sebanyak dua buah. Larva kepiting bakau, S. serrata selama pemeliharaan diberi pakan satu kali sehari. Pakan yang diberikan berupa rotifer (Branchionus plicatilis) dan artemia pada hari kelima dan ketiga. Hasil penelitian menunjukkan bahwa ciri morfologi pembeda antara tahap zoea I dan zoea II adalah mata. Perkembangan zoea I berkisar antara hari 0 sampai dengan hari 4 selanjutnya zoea II antara hari kelima sampai hari ketujuh. Pertumbuhan yang diamati selama masa pemeliharaan hari pertama sampai hari keenam, menunjukkan adanya peningkatan yang signifikan pada hari keempat sampai hari keenam. Tingkat kelangsungan hidup larva S. serrata yang tidak diberi pakan dapat bertahan mencapai tiga hari. Sebaliknya untuk larva yang diberi pakan selama masa pemeliharaan mampu bertahan hingga mencapai tujuh hari.Kata kunci: Larva zoea, Scylla serrata, pertumbuhan, tingkat kelangsungan hidup