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1.
We used an up‐to‐date, a high accuracy CO2 manipulation system to investigate the sensitivity of organisms to CO2 acidification, rearing marine calcifiers under elevated CO2 in running water. We evaluated the effects of elevated partial pressures of carbon dioxide (pCO2) in seawater on larvae of the commercially important marine gastropod Ezo abalone Haliotis discus hannai. In larval Ezo abalone, no effect of exposure to <1100 μatm pCO2 seawater was observed in fertilization, malformation, or mortality rates until 15 h after fertilization. However, compared to control larvae in seawater (450 or 500 μatm pCO2), the fertilization rate and the hatching rate (15 h after fertilization) decreased with increased pCO2 exposure (1650 and 2150 μatm pCO2) and the malformation rate increased significantly, with the larval shell length being smaller 75 h after hatching. These results suggest that ocean acidification will potentially impact the marine population of Ezo abalone as a human food source in the future.  相似文献   

2.
Ocean acidification poses a threat to marine organisms. While the physiological and behavioural effects of ocean acidification have received much attention, the effects of acidification on the susceptibility of farmed shellfish to parasitic infections are poorly understood. Here we describe the effects of moderate (pH 7.5) and extreme (pH 7.0) ocean acidification on the susceptibility of Crassostrea virginica shells to infection by a parasitic polydorid, Polydora websteri. Under laboratory conditions, shells were exposed to three pH treatments (7.0, 7.5 and 8.0) for 3‐ and 5‐week periods. Treated shells were subsequently transferred to an oyster aquaculture site (which had recently reported an outbreak of P. websteri) for 50 days to test for effects of pH and exposure time on P. websteri recruitment to oyster shells. Results indicated that pH and exposure time did not affect the length, width or weight of the shells. Interestingly, P. websteri counts were significantly lower under extreme (pH 7.0; ~50% reduction), but not moderate (pH 7.5; ~20% reduction) acidification levels; exposure time had no effect. This study suggests that extreme levels – but not current and projected near‐future levels – of acidification (?pH ~1 unit) can reduce the susceptibility of eastern oyster shells to P. websteri infections.  相似文献   

3.
The farming of abalone, Haliotis midae L., can be intensified in serial‐pass systems, but water re‐use increases the concentration of NH3 (free ammonia nitrogen, FAN) and reduces water pH. Changing the percentage dietary protein from 33% to 26% reduced the concentration of FAN (F42, 252 = 2.79; P < 0.0001) in a serial‐pass system and did not reduce weight gain (F1, 12 = 1.09; P = 0.31) or length gain (F1, 12 = 1.08; P = 0.31). Low water pH was the most important variable to contribute to a reduction in abalone growth (weight gain: F1, 19 = 64.5; P < 0.0001; r2 = 0.76; length gain: F1, 19 = 41.9; P < 0.0001; r2 = 0.67). In addition, supplemental oxygen (103% saturation) improved length gain (t = 3.45, P = 0.026) in abalone exposed to an average FAN concentration of 2.43 ± 1.1 μg L?1) and an average pH value of 7.6 ± 0.13, relative to a treatment with no oxygen supplementation. Thus, in an abalone serial‐use raceway with three passes, FAN was not the first growth‐limiting variable. It is suggested that future studies should examine the major causes of reduced water pH in serial‐use systems and their effect on the growth and health of H. midae.  相似文献   

4.
The viability of placing abalones (Haliotis discus hannai), sea cucumbers (Apostichopus japonicas) and rockfish (Sebastes schlegeli) in a polyculture system, the effect of this mixed species group on the system's nitrogen (N) and phosphorous (P) budgets, and the growth and food intake of the organisms in the system were examined using a recirculating aquaculture system. Four replicates were set up for each of three treatment groups (abalone only (C), abalone‐sea cucumber (AS) and abalone‐sea cucumber‐rockfish (ASF)) with an experimental period of 60 d. Compared with the C group, in the AS group the abalone survival rate and specific growth rate (SGR) of body weight increased and the harvested abalones from the polyculture system became the main source of N and P output of the polyculture system. However, the N and P output in the water layer did not differ significantly from that in the C group (p > 0.05), and the N utilization rate was significantly higher than that in the C and ASF groups (p < 0.05). Compared with the AS group, in the ASF treatment the SGR of body weight as well as the protease and amylase activities of sea cucumbers were significantly higher (p < 0.05), the water layer and faeces became the main sources of N and P output in the system. These results showed that the AS polyculture mode significantly improved the N and P utilization rates in the system and led to increased aquaculture production.  相似文献   

5.
Floating hapas (fine mesh net enclosures) are a cost‐effective ocean nursery system to culture post‐metamorphic Holothuria scabra to release size. The growth of periphyton biofilm on hapas is a natural food source for early juveniles. This study investigated the effects of periphyton quality (i.e. chlorophyll‐a, phaeopigment, total biomass, autotrophic index or AI), water quality (nutrients, chlorophyll‐a) and environmental parameters (temperature, rainfall) on the temporal variation in the growth and survival of early juvenile (~3 mm) H. scabra reared in floating hapas. Five trials where the juveniles were reared for 60 days each in the eutrophic coastal waters of Bolinao, the Philippines were conducted during different months over 2 years. Significant differences in the growth and survival of juveniles among trials were found. Absolute growth rates (AGR) ranged widely (0.01–0.09 g/day). Trials with high AGR of juveniles (0.07–0.09 g/day) during the first 30 days of rearing had significantly higher chlorophyll‐a (chl‐a) in biofilm (15.9–27.5 mg/m2) and lower AI. Conversely, during the subsequent 30 days, trials with high AGR of juveniles (0.06–0.11 g/day) had significantly lower chl‐a and higher AI. Multivariate analyses showed that chl‐a in biofilm, AI and nutrients in the water column are good indicators of periphyton quality and juvenile growth rates in floating hapas. Further, this study validates the expansion of the feeding mode of juveniles from primarily grazing on microalgae, to feeding on detritus and heterotrophs as they grow. These results are important in optimizing ocean nursery systems.  相似文献   

6.
The seaweed Gracilaria lemaneiformis is largely maricultivated in China, for use as food and as a material in the agar industry. This alga experiences ocean acidification caused by rising atmospheric CO2 levels, and experiences changing light levels caused by self‐shading during the later period of mariculture. In this study, growth and amino acid (AA) content responses of G. lemaneiformis to different CO2 levels (the present and the predicted increased levels) and varying light levels at 28 (±1)°C temperature conditions were investigated. The results showed that a higher light level enhanced algal growth and decreased water loss, but reduced AA accumulation. Decreased pH levels (as a result of CO2 elevation) also enhanced algal growth and reduced AA contents, but the decreases in the AA score at the lower pH levels were not significant under the two light level treatments. In this study, the light treatments had greater influences on growth and AA contents than CO2 levels. The results suggest that G. lemaneiformis quality will be negatively affected during the later mariculture production period as levels of CO2 rise and global temperatures increase.  相似文献   

7.
Red abalone Haliotis rufescens is one of the most valuable mollusks in the international market, but it has a low growth rate. A breeding program is being developed to increase its growth rate in Chile. We estimated the changes in direct heritability (h2), maternal/common environments heritability (m2) and genetic correlations (rG) of growth traits (shell length and width, total mass, flesh mass and foot protein as an indicator of meat quality) measured during 2 years (every 4 months) from the juvenile stage (27 months) to the adult harvesting age (51 months), in 60 full‐sib red abalone families. Heritabilities for growth traits measured in juveniles and young adults (27–35 months of age), were low (0.07–0.17) and not significant. Initial low h2 were associated with significant amounts of maternal/common environmental effects (m2 = 0.4). In young adults and abalone near the harvest age (39–51 months of age) h2 were much higher (0.32–0.75). These results emphasize the importance of multiple estimations of h2 over time. Among meat quality traits, only the h2 for the flesh mass for adults at harvesting age was significant (0.15). We observed strong positive rG (>0.9) between shell sizes (easy to measure) and total and flesh masses (trait more related to market value than shell sizes but harder to measure) for adults at harvesting age. Thus, if the 5% largest 51 month old abalone were selected from the population as broodstock we expect a positively correlated response on flesh mass of 23.4%.  相似文献   

8.
A 115‐day feeding trial and subsequently a 10‐day challenge test with Vibrio parahaemolyticus were conducted to investigate the effects of dietary antimicrobial peptide APSH‐07 on growth performance, immune response, antioxidative status and vibriosis resistance of abalone Haliotis discus hannai (initial body weight: 2.06 ± 0.01 g; initial shell length: 25.42 ± 0.18 mm). Four artificial diets were designed with 0 (artificial diet control), 7.5, 15.0 and 22.5 mg/kg of APSH‐07, respectively. The brown alga Laminaria japonica was used as the live food control. Results showed that the specific growth rates of abalone in the groups with 7.5 and 15.0 mg/kg dietary APSH‐07 were significantly higher than those in the controls (p < .05). The total haemocyte counts and respiratory burst activity in haemolymph of abalone in the group with 7.5 mg/kg of dietary APSH‐07 were significantly higher than those in the groups with 0 and 22.5 mg/kg of dietary APSH‐07 (p < .05). The gene expression levels of Mn‐superoxide dismutase and thioredoxin peroxidase 2, and the activities of glutathione peroxidase in the group with 7.5 mg/kg of dietary APSH‐07 were significantly higher than those in the other groups (p < .05). Cumulative mortality of abalone after the challenge test was significantly decreased in the group with 7.5 mg/kg of dietary APSH‐07 supplementation. Supplementation of 22.5 mg/kg dietary APSH‐07 significantly increased the cumulative mortality. In conclusion, 7.5 mg/kg of dietary APSH‐07 supplementation had the better growth performance, higher antioxidation, immune and disease resistance capacity of abalone. Excessive supplementation of dietary antimicrobial peptide APSH‐07 (22.5 mg/kg) had significantly negative effects. Further studies are needed to determine the optimal level of dietary APSH‐07 supplementation for abalone.  相似文献   

9.
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10.
The Xishi abalone (Haliotis gigantea) is an economically significant aquaculture species in southern China. We identified a novel orange‐muscle mutation present in less than 2% of the cultured population. High‐performance liquid chromatography and electrospray ionization mass spectrometry identified zeaxanthin and β‐carotene as the two main pigments present in the orange‐muscle abalone. The concentrations of zeaxanthin and β‐carotene detected in the orange‐muscle abalones were significantly higher than those detected in the common abalones (p < 0.01). Notably, the concentration of zeaxanthin was approximately 16.5 times higher in orange‐muscle abalones than in common abalones, which was also the species with highest carotenoid content reported in shellfish to date. Furthermore, the contents of total amino acids and essential amino acids in the orange‐muscle abalone were higher than that in the common abalone, though not significantly, while the content of non‐essential amino acids was significantly higher in the orange‐muscle abalone than that in the common abalone (p < 0.05). The saturated fatty acid content in the orange‐muscle abalones was slightly lower than that in the common abalones, and the unsaturated fatty acid content was higher in the orange‐muscle abalones than that in the common abalones. These results could provide a basis for characterizing the mechanism by which carotenoids accumulate in abalones and further guide the breeding of abalone with orange‐muscle mutants in the future.  相似文献   

11.
Ocean acidification, resulted from high level of carbon dioxide (CO2) dissolved in seawater, may disturb the physiology of fish in many ways. However, it is unclear how acidification may impact the growth rate and/or growth hormones of marine fish. In this study, we exposed juvenile orange‐spotted groupers (Epinephelus coioides) to seawater of different levels of acidification: a condition predicted by the Intergovernmental Panel on Climate Change (pH 7.8–8.0), and a more extreme condition (pH 7.4–7.6) that may occur in coastal waters in the near future. After 6 weeks of exposure, the growth rates of fish in pH 7.4–7.6 were less than those raised in control water (pH 8.1–8.3). Furthermore, exposure at pH 7.4–7.6 increased blood pCO2 and HCO3? significantly; exposure at pH 7.8–8.0, meanwhile, did not affect acid–base chemistry. Moreover, exposure to pH 7.4–7.6 resulted in lower levels of hepatic igf1 (insulin‐like growth factor I) mRNA, but did not affect levels of pituitary gh (growth hormone) or hypothalamus psst2 and psst3 (prepro‐somatostatin II and III). The results show that highly acidified seawater suppresses growth of juvenile grouper, which may be a consequence of reduced levels of IGF‐1, but not due to diminished growth hormone release.  相似文献   

12.
In this study, we have tested the effect of seaweed stocking density in an experimental seaweed biofilter using the economically important red seaweed Hydropuntia cornea integrated with the cultivation of the pink shrimp Farfantepenaeus brasiliensis. Nutrient removal efficiency was evaluated in relation to seaweed stocking density (2.5, 4, 6 and 8 g fw L?1). Total ammonia nitrogen (TAN) was the main nitrogen source excreted by F. brasiliensis, with concentrations ranging from 41.6 to 65 μM of NH4+‐N. H. cornea specific growth rates ranged from 0.8 ± 0.2 to 1.4 ± 0.5% day?1 with lowest growth rates at higher seaweed stocking density (8 g fw L?1). Nutrient removal was positively correlated with the cultivation densities in the system. TAN removal efficiency increased from 61 to 88.5% with increasing seaweed stocking density. Changes in the chemical composition of the seaweed were analysed and correlated with nutrient enrichment from shrimp effluent. The red seaweed H. cornea can be cultured and used to remove nutrients from shrimp effluents in an integrated multi‐trophic aquaculture system applied to a closed recirculation system. Recirculation through seaweed biofilters in land‐based intensive aquaculture farms can also be a tool to increase recirculation practices and establish full recirculation aquaculture systems (RAS) with all their known associated benefits.  相似文献   

13.
The γ‐aminobutyrate type A receptor‐associated protein (GABARAP) is a ubiquitin‐like modifier implicated in membrane trafficking and fusion events involving the γ‐aminobutyrate type A receptor, autophagy and apoptosis. In this study, the gene encoding GABARAP was cloned from swimming crab Portunus trituberculatus (PtGABARAP) based on the expression sequence tag (EST). The full‐length cDNA of 664 bp includes a 5′ untranslated region (UTR) of 87 bp, a 3′ UTR of 223 bp with a poly(A) tail, and an open reading frame (ORF) of 354 bp encoding a polypeptide of 117 amino acids with a predicted molecular weight of 13.96 kDa. The deduced amino acid sequence shares high similarity (93%–100%) with GABARAPs from other species and includes a conserved Atg8 domain. In a phylogenetic analysis PtGABARAP clustered with GABARAPs from other species, and more widely with other GABARAP family proteins. The impact of elevated ocean acidification (OA) on P. trituberculatus behaviours was investigated, and real‐time RT‐PCR revealed that PtGABARAP expression was up‐regulated after OA exposure. Ocean acidification also caused crabs anxiety‐like behaviours, like the shoal average speed increase, preference for dark environment (scototaxis) and fast exploration. The results indicated that GABARAP might be involved in the interactions of GABAA receptors and elevated‐CO2 seawater.  相似文献   

14.
Tilapia juveniles are a very important life stage, and reliably assessing their growth performance is of prime importance in aquaculture production. The suitability of the RNA/DNA as a bioindicator for growth evaluation in tilapia has not yet been reported. In this study, we examined suitability of RNA/DNA ratio for assessing growth of tilapia juveniles and variation in the ratio under the concurrent influences of temperature and salinity using the central composite design and response surface methodology. Results showed that under our experimental conditions, the synergistic effects of temperature and salinity on the RNA/DNA ratio were highly significant (P < 0.01), and the ratio varied with the two factors in a nonlinear fashion; the temperature × salinity interaction was detected at 1% significance level, and had a negative effect on the RNA/DNA ratio particularly at higher temperatures. Temperature was found to have a greater influence on RNA/DNA ratios than salinity. A model of the relation between RNA/DNA, temperature and salinity was developed, with an R2 greater than 98%. The linear relationships of absolute growth, cumulative growth and specific growth of tilapia juveniles to RNA/DNA ratio all showed an R2 of greater than 95%. Our results indicate that the RNA/DNA ratio was a responsive and accurate bioindicator for evaluating the growth performance of juvenile tilapia. These ratio‐based models are neither temperature‐ nor salinity‐dependent, and could be readily applicable to freshwater or brackish water aquaculture within temperature–salinity combinations ranging from 16 to 36°C and 0–16 ppt.  相似文献   

15.
The benefits of exposing eastern oysters to air during commercial culture have not been well‐characterized. An adjustable longline system (ALS) designed in Australia and recently adopted by the nascent aquaculture industry in the northern Gulf of Mexico, allows growing oysters at any position in the water column and is perfectly suited to study the benefits of air exposure. Four‐month old diploid oysters were deployed in an ALS and divided into three groups: 1) oysters exposed to air daily for 8–12 hr during low tide, 2) oysters exposed to air weekly (~24 hr once a week), and 3) oysters kept subtidally. Oyster mortality and growth rates, Perkinsus marinus load and condition index were then determined every 3 months over 2 years, while refrigerated shelf life and Vibrio vulnificus load were determined in summer and early fall of the second year. Summer mortalities were delayed, P. marinus infection intensities tended to be lower and condition index was significantly higher in oysters exposed to air daily compared with oysters exposed to air weekly or held subtidally. Shell heights of oysters exposed to air daily were lower for most of the study due to a lower growth rate during the initial sampling interval following deployment. No consistent differences were found in V. vulnificus loads or refrigerated shelf lives between the groups. It is recommended that ALS be set so that oysters are kept subtidally fall through spring to promote growth, and exposed to air daily during summer to delay P. marinus proliferation.  相似文献   

16.
The Kumamoto oyster (Crassostrea sikamea) and the Portuguese oyster (C. angulata) are important aquaculture species which naturally coexist along the southern coast of China. To understand the potential feasibility of hybridization between the two species, we conducted two‐by‐two factorial cross‐experiments in Beihai (Guangxi province), and also compared the survival and growth of the hybrids to that of the two parental progenies during the grow‐out period from July 2014 to July 2015. Genetic analysis confirmed that the hybrid spats were true hybrids. Additionally, the biochemical composition of the 1‐year‐old oyster progenies was determined. In July 2015, the mean shell height of the hybrids was 42.98 ± 6.29 mm, which was higher than that of the Kumamoto oyster progeny. The cumulative survival rate of the hybrids was 26.37 ± 1.32%, which was higher than that of the progeny of the Portuguese oyster. Mean lipid content of the hybrids was 13.65 ± 1.63% of dry weight, which showed obvious heterosis compared to those of the two parental progenies. Observation of gonads revealed that all hybrids were completely fertile. Furthermore, relative expression of the lipid homeostasis genes, SREBP (sterol regulatory element‐binding proteins), PPARα (peroxisome proliferator‐activated receptor) and INSIG (insulin‐induced gene) were found to vary between parental progenies and the hybrids, thus providing a possible reason for difference in the lipid contents of these experimental groups. Overall, the hybrids were viable, rich in lipid and completely fertile and thus could serve as a promising aquaculture stock for oyster breeding in southern China.  相似文献   

17.
This study is aimed at the isolation and screening of alginate lyase‐producing bacteria from the gastrointestinal tracts of hybrid abalone, Haliotis rubra x H. laevigata, as probiotic candidates. Six bacterial isolates were detected to produce alginate lyase. Of these, the isolate with the highest alginate‐lyase activity was identified as Enterobacter ludwigii strain EN‐119, displaying 99% similarity of 16S rDNA sequence. Further assays indicated that E. ludwigii showed good viability and stability when it was incorporated into manufactured pellets and stored at 4°C for 7 days. The isolate also had high tolerance of high salinity (35 mg/L), low pH in simulated stomach juice (5) and to simulated intestinal juice containing surfactants such as bile salts and gastric enzymes (pepsin and trypsin). Additionally, a short, preliminary study indicated that supplementation of E. ludwigii via manufactured pellets improved the total weight gain and specific growth rate of hybrid abalone. These results suggest that E. ludwigii is a potential probiont for shortening the culture period of hybrid abalone.  相似文献   

18.
Bivalve molluscs, such as oysters, are threatened by shifts in seawater chemistry resulting from climate change. However, a few species and populations within a species stand out for their capacity to cope with the impacts of climate change‐associated stressors. Understanding the intracellular basis of such differential responses can contribute to the development of strategies to minimise the pervasive effects of a changing ocean on marine organisms. In this study, we explored the intracellular responses to ocean acidification in two genetically distinct populations of Sydney rock oysters (Saccostrea glomerata). Selectively bred and wild type oysters exhibited markedly different mitochondrial integrities (mitochondrial membrane potential) and levels of reactive oxygen species (ROS) in their hemocytes under CO2 stress. Analysis of these cellular parameters after 4 and 15 days of exposure to elevated CO2 indicated that the onset of intracellular responses occurred earlier in the selectively bred oysters when compared to the wild type population. This may be due to an inherent capacity for increased intracellular energy production or adaptive energy reallocation in the selectively bred population. The differences observed in mitochondrial integrity and in ROS formation between oyster breeding lines reveal candidate biological processes that may underlie resilience or susceptibility to ocean acidification. Such processes can be targeted in breeding programs aiming to mitigate the impacts of climate change on threatened species.  相似文献   

19.
The bioflocs technology proved to be a sustainable technique used in zero‐water exchange shrimp culture systems. However, the pH and alkalinity may decrease due to the biofloc formation process and Nitrification. A 48‐day experiment was performed to investigate the effects of different pH (7.1–7.6; 7.6–8.1) conditions on water quality, the growth and the health status of shrimp in biofloc technology (BFT) through using sodium bicarbonate to adjust pH respectively. Two pH treatments and one control were compared: T0 — control, T1 — pH 7.6 — NaHCO3, T2 — pH 8.1 — NaHCO3, each treatment consisted of three replicate tanks (90 L water volume) and each replicate stocked with 30 shrimp (equivalent to 333 shrimp m?3). Significant physical, chemical and biological differences (P < 0.05) were detected among treatments. At the end of the experiment, water quality, the growth and the immune response of shrimp in control were significantly lower (P < 0.05) than the other treatments. Moreover, the T2 treatment had a better performance in these three aspects. The results indicated that it was necessary to adjust the pH and alkalinity in the BFT, and a higher pH as well as alkalinity for shrimp growth and the stability of the BFT were more favourable.  相似文献   

20.
Parentage analysis in aquaculture determines genealogical relationships between broodstock and progeny when the parents are unknown. Thus, parentage analysis is a useful tool to establish pedigree reports in molecular‐assisted selection programs. Here, we evaluated 10 heterologous microsatellite markers for parentage assignment in abalone hybrids produced from 43 abalone broodstocks of red abalone (Haliotis rufescens) and Japanese abalone (H. discus hannai). The allele frequencies, exclusion probabilities and broodstock contributions were calculated using CERVUS, PAPA and GERUD software. The polymorphic information content (PIC) values showed that most of the microsatellite loci were highly informative (>0.7) and more than 90% of parentage assignment was possible with a minimum of 5–6 microsatellite markers. Parentage assignment for hybrid and pure‐red progeny showed a better performance than pure‐Japanese progeny. This result could be due to the high level of allele loss in the parental genotypes. In addition, results indicated that only two sires contributed over 80% and 90% of red and hybrid progenies, respectively. This study gives a new molecular tool to support marker‐assisted selection in abalone hybrids produced in Chile.  相似文献   

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