| 1. |
- Clements, Jeff C., et al.
(författare)
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Nitrogen removal potential of shellfish aquaculture harvests in eastern Canada: A comparison of culture methods
- 2019
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Bivalve farming can contribute to nutrient removal in coastal and estuarine systems, as bivalves directly incorporate nutrients into their tissues and shells. We conducted a meta-analysis to compare the nitrogen removal potential (NRP; i.e., percentage of nitrogen in tissues and shells) of mussels, Mytilus edulis, and oysters, Crassostrea virginica. We then used species-specific NRPs to determine and compare the total and per-hectare NRPs for four shellfish aquaculture methods used in two Atlantic Canadian provinces – New Brunswick (NB) and Prince Edward Island (PEI) – based on current harvest biomasses. Finally, we determined the contribution of current shellfish farming to nitrogen load mitigation for a subset of bays in NB and PEI. Results revealed that on a per-weight basis, NRP was similar for the tissues of mussels and oysters, while mussel shells had a significantly higher percentage of nitrogen than oyster shells. Collectively, shellfish harvesting has the capacity to remove a mean annual total of 99088 kg and 204571 kg of nitrogen from NB and PEI, respectively. Given current harvesting practices for four culture methods employed in the region, suspended mussel culture provides the greatest NRP per hectare of farm area, followed in sequence by suspended mussel and oyster mixed culture, suspended oyster culture, and bottom oyster culture. Preliminary analysis suggested that harvests in the region typically remove <10% of the total nitrogen load on the bay scale, with the exception of bays where nitrogen loads are low and farming intensity is high (where shellfish harvesting can remove higher percentages of nitrogen loads). Ultimately, harvests from shellfish farming in NB and PEI have the capacity to remove substantial amounts of nitrogen from local bays. Future studies assessing the influence of shellfish farming on full nutrient budgets across bays with varying physicochemical conditions will enhance our understanding the role of shellfish farms in nearshore nutrient dynamics, both regionally and globally. © 2019
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| 2. |
- Jacobs, P., et al.
(författare)
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Successful rearing of Ostrea edulis from parents originating from the Wadden Sea, the Netherlands
- 2020
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 18:November
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Tidskriftsartikel (refereegranskat)abstract
- Since 2017, the European flat oyster (Ostrea edulis) reappeared in the Wadden Sea after decades of absence. In several countries, restoration and reinforcement projects have been initiated. Better insight in Ostrea behaviour is needed to ensure sustainable conservation in the future. In order to acquire substantial numbers of oysters for eco-physiological and transplant experiments without threatening the small local population, indoor rearing facilities were set-up at Royal NIOZ. Here, a broodstock of 38 adults originating from the western Wadden Sea, produced over 21 million larvae in 10 batches within 3 months (Sept-Nov 2018). Release of larvae and rearing took place at a water temperature of 19.7 ± 0.6 °C and a salinity of 30.5 ± 0.5 PSU. Outbreaks of Vibrio bacteria did not occur. The growth rate before settlement was 1.5–1.7 μm per day, which was at the low end of growth rates reported in previous studies. The first competent larvae were observed 17–22 days after release. Size at settlement varied between 255−325 μm. Survival until settlement was 0.96−0.98 per day. After settlement, growth rates increased to 30−47 μm per day, with batches that were released in September having a significantly higher growth rate and initial size compared to larvae that were released later. Mortality from release to the end of the experiment (Feb 2019) was 0.04−0.05 per day. A cryopreservation trial did not result in living larvae after thawing, most likely due to their advanced development when preserved. The larvae and juveniles were negatively tested for the parasite Bonamia ostrea and can thus be used in oyster conservation and restoration projects. Recommendations for future breeding attempts include the use of a higher water temperature and slightly higher food concentrations. © 2020 The Authors
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| 3. |
- Kurta, Khrystyna, et al.
(författare)
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Evaluating the potential of improving sperm quality traits in farmed Arctic charr (Salvelinus alpinus) using selective breeding
- 2022
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- Arctic charr (Salvelinus alpinus) is a high-value species for the Nordic aquaculture. The highly variable reproductive performance that is commonly observed in commercial farms is hindering the expansion of the Arctic charr industry in Sweden. Traits related to sperm motility (total motility; curvilinear velocity; average path velocity; straight-line velocity) and concentration can play a pivotal role in male fertility. Selective breeding practices could offer solutions and contribute to improving male fertility. The current study aimed to investigate the magnitude of genetic variance for sperm quality traits in a selectively bred population of Arctic charr from Sweden and evaluate the possibility of their improvement through selection. Sperm motility and concentration were recorded using a computer-assisted semen analysis (CASA) system and a NucleoCounter, respectively, in over 400 males from year-class 2017. Double digest restriction-site associated DNA sequencing (ddRAD-seq) was applied in a subset of the recorded animals (n = 329), resulting in the detection of over 5000 single nucleotide polymorphisms (SNPs). Moderate heritability estimates were obtained for the recorded semen traits using both pedigree (0.21-0.32; SE 0.09) and genomic (0.23-0.26; SE 0.09) relationship matrices. A genome-wide association study (GWAS) detected a single SNP significantly associated (P < 1e-05) with total sperm motility on chromosome LG7 in relatively close proximity (500 Kb) to PTPN11 a gene previously associated with sperm quality traits in mammals. Moreover, weighted single-step genomic best linear unbiased prediction (WssGBLUP) pinpointed genomic regions explaining more than 3 % of the additive genetic variance for both the motility traits and the sperm concentration. Finally, the efficiency of genomic prediction was tested using a 3-fold cross-validation scheme. Higher prediction accuracy for total motility and velocities (both curvilinear and average path) was obtained using genomic information (0.26-0.29, SE 0.03-0.06) compared to pedigree (0.20-0.28, SE 0.04-0.07), while for sperm concentration a pedigree-based model (0.22 SE 0.03) was more efficient than the genomic model (0.14 SE 0.04). Overall, our results indicate that the recorded sperm quality traits are heritable, and could be improved through selective breeding practices.
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| 4. |
- Mafambissa, Mizeque, et al.
(författare)
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Experimental spat collection of the pearl and rocky shore oysters on ceramic tile substrates
- 2024
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Ingår i: Aquaculture Reports. - 2352-5134. ; 36
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Tidskriftsartikel (refereegranskat)abstract
- Temporal and spatial variation in oyster larvae settlement is a crucial factor determining the abundance and success of adult populations in their natural environment. The overall understanding of oyster recruitment provides information on site selection and strategies employed for obtaining spats for oyster culture. In this study, spat of Pinctada capensis and Saccostrea cucullata were collected from four selected sites in a sub-tropical setting at Inhaca Island, Southern Mozambique during an experimental period of 8 months to assess the effect of different factors (season, duration and surface) on spat settlement and abundance. Ceramic tiles were deployed as artificial substrates from the surface to 5 m depth. They were replaced monthly. Overall, settlement on ceramic tiles was higher for S. cucullata than for pearl oyster P. capensis. There was a tendency for higher numbers of spat settling during the summer than winter for both species. For both species larger numbers of recruits were found on tiles deployed for four months than for two months and on the roughly textured surfaces compared to smooth. The results have also indicated that the ceramic tiles could be used as substrate for rocky shore oyster S. cucullata settlement in the late summer.
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| 5. |
- Nyman, Andreas, et al.
(författare)
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Effects of microbe- and mussel-based diets on the gut microbiota in Arctic charr (Salvelinus alpinus)
- 2017
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 5, s. 34-40
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Tidskriftsartikel (refereegranskat)abstract
- A major challenge in aquaculture is finding nutrient resources that do not compete with human demandand do not threaten ecological sustainability. Single cell proteins, such as filamentous fungi and yeasts,have similar nutrient profiles to fish meal, grow fast under optimal conditions and contain high amountsof protein, making them attractive candidates as alternative nutrient sources for farmed fish. Moreover,the cell walls of yeasts and filamentous fungi have bioactive properties, potentially mediated via theintestinal microbiota, that positively affect the intestinal health of fish. The microbiota in fish is not wellexplored and it is uncertain how different dietary components influence its composition.Five experimental diets were fed to Arctic charr (Salvelinus alpinus) to investigate their effects on gutmicrobiota. The fish meal in a reference diet was replaced with either intact or extracted yeast cells ofthe species Saccharomyces cerevisiae, the filamentous fungi Rhizopus oryzae or meal from blue mussel(Mytilus edulis). The microbiota was characterised in samples collected from the proximal and distalintestine using 16S rRNA gene amplicon sequencing with Illumina MiSeq.Sequence data showed that the gut microbiota was dominated by Firmicutes and Proteobacteria, whichrepresented 85% of total community abundance, with lactic acid bacteria representing 36.2%. Principalcomponent analysis (PCA) of the data revealed that the microbiota in proximal and distal regions ofthe intestine had similar composition and that replacement of fish meal with yeast and filamentousfungi affected microbiota composition, primarily with higher relative proportions of Photobacterium andLactobacillus.Lactic acid bacteria were a dominant fraction of the intestinal microbiota in Arctic charr. Microbialbased feeds were associated with similar changes in microbiota composition, but contrasting to the fish-meal based reference diet. Microbiota composition was similar in the proximal and distal gut, but dietaryresponses were specific to gut segment.
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| 6. |
- Olsén, K. Håkan, 1952-, et al.
(författare)
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Chemical foraging stimulation in the omnivorous species crucian carp, Carassius carassius (Linnaeus 1758)
- 2018
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Ingår i: Aquaculture Reports. - : Elsevier. - 2352-5134. ; 12, s. 36-42
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Tidskriftsartikel (refereegranskat)abstract
- In fish aquaculture, great efforts are made to develop feed that excludes marine fish proteins and oils, or at least to decrease these parts to a minimum but the fish might not be attracted to or might not eat the alternative feed. Molecules detected by the olfactory sense can induce arousal and search behavior that attract the fish and induce foraging. In the present study, we have examined whether mussel extracts can induce foraging behavior in crucian carp, Carassius carassius. Free amino acids are present in high concentrations in mussels and they are detected at low concentrations by olfaction and induce food search behavior in several fish species. We studied the behavior responses to water extracts of mussel powder compared to extracts of a plant-based commercial carp feed. Extracts of different concentrations were administered in glass aquaria with individual fish. The tests began with 5 min with only tap water and this was followed by 5 min with extracts or amino acid solutions. The behavior was recorded with a video camera. The initial control period was compared to the following period with odors. No significant foraging response was observed with extracts of mussels, but the commercial carp feed extract induced increased bottom snapping. Synthetic mixtures of five nutritional amino acids present at high concentrations in both extracts did not give any significant foraging response. Our results show that mussels are not suitable as a protein source in feed to crucian carp.
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| 7. |
- Olsén, K. Håkan, et al.
(författare)
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Feeding stimulants in an omnivorous species, crucian carp Carassius carassius (Linnaeus 1758)
- 2016
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 4, s. 66-73
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Tidskriftsartikel (refereegranskat)abstract
- Many fish are during feeding dependent on both an olfactory and gustatory sense. Olfaction that acts as the distance sense induces arousal, food search behaviour and attraction to the source, followed by examination of food items by the gustatory sense. During buccal handling the fish decide if the feed will be rejected or swallowed. Amino acids are often stimulatory to the gustatory sense and can act as feeding stimulants. There are, however, inter-species differences concerning what kinds of amino acids act as feeding stimulants or deterrents. The species differences are probably dependent on the natural food choice. As feeding stimulating molecules increase feeding and growth, but deterrents have the reverse effect, it is important to know what kind of molecules have either effect. In the present study we record mouth handling time in the omnivorous crucian carp, Carassius carassius, of agar pellets containing water extracts of meal consisting of ordinary food pellets, blue mussels or a commercial carp attractant. These tests were followed by testing with agar pellets with synthetic amino acids, based on the content of the water extracts of the food pellets that was the only feeding stimulant. Neither extracts of mussel meal or of commercial carp attractants had a stimulating effect, i.e. no significant difference in handling time compared to agar pellets with only water. A mixture of five of the major amino acids in the food pellet extract (40 mM alanine, 20 mM glycine, 20 mM arginine, 8 mM serine, 8 mM leucin) gave a significant longer handling time compared to agar pellets with only water. The handling time was also longer for the three amino acids that had the highest concentrations (40 mM Ala, 20 mM Gly, 20 mM Arg) and finally with only alanine (128 mM). Agar pellets with only Ala gave, however, a significant shorter handling time compared to agar pellets with food pellet extract. The mussel meal extract had the same content of free amino acids and their ranking order was the same as in extracts of food pellets, but at much higher concentrations. Based on the free amino acid content, the mussel extract should have stimulated feeding. This indicates that the mussel extract contained compounds that acted as feeding deterrents in omnivorous crucian carp that do not feed on blue mussels in their natural environment. Previous studies have shown that blue mussel extracts act as feeding stimulants in several bottom feeding carnivorous fish. We finally tested betaine (100 mM) but the molecule had no significant stimulating effect that has been observed in some other fish species. © 2016 The Authors
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| 8. |
- Palaiokostas, Christos
(författare)
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Genetic parameters and genomic prediction of resistance to koi herpesvirus disease using a low-density SNP panel on two Amur mirror carp populations
- 2023
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Ingår i: Aquaculture Reports. - 2352-5134. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- Koi herpesvirus disease (KHVD), caused by Cyprinid herpesvirus-3 (CyHV-3), is one of the most serious threats to carp farming. In the present study, we investigated the efficiency of a low-density (LD) SNP panel for estimating genetic parameters and breeding values to KHVD resistance in the Amur mirror carp (AMC). Two populations (Pop 1 and Pop 2) of AMC generated from unrelated parents were created using a partial factorial design. One-year old fish (Pop 1 = 1500 individuals.; Pop 2 = 1200 individuals) were challenged with CyHV-3 and phe-notyped to KHVD resistance. 218 SNPs originating from a medium genotyping platform previously applied to Pop 1 (15615 SNPs; denoted as MD panel) with the highest association to KHVD resistance were used as a LD panel to genotype individuals of Pop 2. Genetic parameters and estimated pedigree-based BLUP (EBV) and genomic-based GBLUP (GEBV_MD and GEBV_LD) breeding values were calculated and obtained for Pop 1 using either pedigree, MD or LD panel and for Pop 2 using either pedigree or the LD panel. The heritability estimates of KHVD resistance were very high for both populations ranging from 0.42 to 0.96. Selection for KHVD resistance in Pop 2 using the LD panel would have led to a relative increase of similar to 7% in prediction accuracy compared to the pedigree-based selection. Pearson correlation coefficients between pedigree-based and genomic-based estimated breeding values (EBV vs. GEBV_MD; EBV vs. GEBV_LD; GEBV_MD vs. GEBV_LD) showed a strong association for both populations (0.79 - 0.91). In addition, the concordance rate of individuals selected by pedigree-based (EBV) and genomic-based breeding values (GEBV_MD and GEBV_LD) within selection pressures of 5%, 10% and 20% were not statistically different in most cases. In conclusion, the low-density SNP panel could be useful for a selection program focused on the genetic improvement of KHVD resistance.
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| 9. |
- Palaiokostas, Christos
(författare)
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Predicting for disease resistance in aquaculture species using machine learning models
- 2021
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Ingår i: Aquaculture Reports. - : Elsevier BV. - 2352-5134. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Predicting disease resistance is one of the most prominent applications of aquaculture selective breeding. Reductions in genotyping costs have allowed the implementation of genomic selection in an abundance of aquaculture species and their related diseases showing promising results. Machine learning (ML) models can be of value for prediction purposes, as suggested by several studies in both plants and livestock. The current study aimed to test the efficiency of various ML models in predicting disease resistance using both simulated and real datasets. More specifically, models like decision trees (DT), support vector machines (SVM), random forests (RF), adaptive boosting (Adaboost) and extreme gradient boosting (XGB) were benchmarked against genomic best linear unbiased prediction for threshold traits backend by Markov chain Monte Carlo (GBLUP-MCMC) both in terms of prediction efficiency and required computational time. Moreover, the model ranking was tested in datasets where the ratio between the two observed phenotypes (resistant vs non-resistant) was unbalanced. Across all tested datasets, XGB ranked first with a slight advantage over GBLUP-MCMC, ranging between 1-4 %. SVM and RF delivered predictions in tight proximity with the ones from XGB and GBLUP-MCMC. In addition, predictions 3-4 % lower compared to GBLUP-MCMC were obtained with Adaboost. On the other hand, the predictions from DT were consistently low (-40 % lower compared to GBLUP-MCMC). All tested ML models had significantly reduced computational requirements than GBLUP-MCMC. In the case of XGB, the computational requirements were reduced more than 20-fold as opposed to GBLUP-MCMC under the settings of the current study. RF delivered both competitive predictions and was highly efficient in terms of the required computational time (-3 min). Overall, the results of the current study suggest that ML models can be valuable tools in aquaculture breeding studies for disease resistance.
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