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Copyright of Journal of New Brunswick Studies / Revue d'etudes sur le Nouveau-Brunswick is the property of Journal of New Brunswick Studies and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT The behavior of stage IV American lobster (Homarus americanus) larvae in relation to various water temperatures was observed in laboratory. Time budgets were documented in 2009 in trials using [...]

Abstract Background Sex differences in the magnitude or direction of mutational effect may be important to a variety of population processes, shaping the mutation load and affecting the cost of sex itself. These differences are expected to be greatest after sexual maturity. Mutation-accumulation (MA) experiments provide the most direct way to examine the consequences of new mutations, but most studies have focused on juvenile viability without regard to sex, and on autosomes rather than sex chromosomes; both adult fitness and X-linkage have been little studied. We therefore investigated the effects of 50 generations of X-chromosome mutation accumulation on the fitness of males and females derived from an outbred population of Drosophila melanogaster. Results Fitness declined rapidly in both sexes as a result of MA, but adult males showed markedly greater fitness loss relative to their controls compared to females expressing identical genotypes, even when females were made homozygous for the X. We estimate that these mutations are partially additive (h ~ 0.3) in females. In addition, the majority of new mutations appear to harm both males and females. Conclusions Our data helps fill a gap in our understanding of the consequences of sexual selection for genetic load, and suggests that stronger selection on males may indeed purge deleterious mutations affecting female fitness.

In North America, studies regarding effects of CO2-induced low pH in bivalve aquaculture are largely restricted to the US Pacific coast. Studies on species from the northwest Atlantic are lacking. Furthermore, information on the roles of intergenerational exposure and biological sex in bivalve responses to low pH, particularly in an aquaculture-specific context, is scant. We tested if short-term (1 month) exposure to CO2-induced reductions in pHNBS affected the reproductive development of male and female eastern oysters (Crassostrea virginica) during hatchery-specific reproductive conditioning and whether maternal and/or paternal exposure influenced larval responses. Reduced pH (7.5–7.7) increased the rate of reproductive development in both males and females. There was no indication of intergenerational effects; adult pH conditions did not affect early larval development. In contrast, low pH conditions experienced by gametes during spawning, fertilization, and embryo incubation (48 h) resulted in higher larval survival (+6–8% from control), reduced shell height (−2 to 3 µm), and increased deformities (abnormal shell shape; +3–5%). We suggest that local adaptation to acidic land runoff may account for the positive effects of low pH observed in this study. Bioeconomic assessments are now needed to understand the implications of reduced pH on aquaculture operations in these regions of Atlantic Canada. [ABSTRACT FROM AUTHOR]

Interactions between environmental factors and complex life‐history characteristics of marine organisms produce the genetic diversity and structure observed within species. Our main goal was to test for genetic differentiation among eastern oyster populations from the coastal region of Canadian Maritimes against expected genetic homogeneity caused by historical events, taking into account spatial and environmental (temperature, salinity, turbidity) variation. This was achieved by genotyping 486 individuals originating from 13 locations using RADSeq. A total of 11,321 filtered SNPs were used in a combination of population genomics and environmental association analyses. We revealed significant neutral genetic differentiation (mean FST = 0.009) between sampling locations, and the occurrence of six major genetic clusters within the studied system. Redundancy analyses (RDAs) revealed that spatial and environmental variables explained 3.1% and 4.9% of the neutral genetic variation and 38.6% and 12.2% of the putatively adaptive genetic variation, respectively. These results indicate that these environmental factors play a role in the distribution of both neutral and putatively adaptive genetic diversity in the system. Moreover, polygenic selection was suggested by genotype–environment association analysis and significant correlations between additive polygenic scores and temperature and salinity. We discuss our results in the context of their conservation and management implications for the eastern oyster. [ABSTRACT FROM AUTHOR]

Green water is a technique commonly used in aquaculture, that consists of adding live algae in the water culture and its benefits have been shown for several species. Several hypotheses exist to explain the benefits of green water: increase in nutritional value; action as a probiotic; increase in contrast to reveal preys for larvae; or increase in predator behaviour of larvae. Green water produced with a mix of strains Isochrysis galbana and Chaetoceros muelleri (50:50, cells:cells) applied in four different ways was tested. The survival and the growth of American lobster (Homarus americanus) between stage I and stage IV post-larvae were not affected by the addition of live algae. The lipid classes were not affected by the addition of algae and limited variation was observed in the fatty acids and bacterial profiles. Furthermore, the green water techniques had a limited effect on the behaviour of post-larvae stage IV lobster at releasing. Behaviour was mostly affected by the age of post-larvae. The bacteria Lewinella sp., Leucothrix sp. and Thiothrix sp. appeared to represent a common and core component of Stage IV lobster post-larvae microflora. The results show that the algae do not increase either nutritional value or feed intake of the lobster larvae. Probiotic effect may be more important when larvae are raised in a close system where potential bacterial pathogens could have more chances to colonize the culture. Also, the dark green colour of the larval tank used in this study may have mimicked the effect of green water in the control group. Biochemical results suggest that dietary supplementation with phospholipids and DHA is needed in a lobster hatchery using frozen Artemia and our open formula Dry mix. [ABSTRACT FROM AUTHOR]

Dense single nucleotide polymorphism (SNP) arrays are essential tools for rapid high-throughput genotyping for many genetic analyses, including genomic selection and high-resolution population genomic assessments. We present a high-density (200 K) SNP array developed for the Eastern oyster (Crassostrea virginica), which is a species of significant aquaculture production and restoration efforts throughout its native range. SNP discovery was performed using low-coverage whole-genome sequencing of 435 F1 oysters from families from 11 founder populations in New Brunswick, Canada. An Affymetrix Axiom Custom array was created with 219,447 SNPs meeting stringent selection criteria and validated by genotyping more than 4,000 oysters across 2 generations. In total, 144,570 SNPs had a call rate >90%, most of which (96%) were polymorphic and were distributed across the Eastern oyster reference genome, with similar levels of genetic diversity observed in both generations. Linkage disequilibrium was low (maximum r² ~0.32) and decayed moderately with increasing distance between SNP pairs. Taking advantage of our intergenerational data set, we quantified Mendelian inheritance errors to validate SNP selection. Although most of SNPs exhibited low Mendelian inheritance error rates overall, with 72% of called SNPs having an error rate of <1%, many loci had elevated Mendelian inheritance error rates, potentially indicating the presence of null alleles. This SNP panel provides a necessary tool to enable routine application of genomic approaches, including genomic selection, in C. virginica selective breeding programs. As demand for production increases, this resource will be essential for accelerating production and sustaining the Canadian oyster aquaculture industry. [ABSTRACT FROM AUTHOR]