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Bacteria are an integral component of their host. However, information about the microbiota living in and around many aquatic animals is lacking. In this study, multiplex bar-coded pyrosequencing of the 16S ribosomal RNA gene was used to monitor the dynamics of abalone, Haliotis discus hannai, bacterial communities in the intestine, water from cement culture ponds, and surrounding sea areas. Correlations between the bacterial communities and common aquaculture diseases were also evaluated. A total of 329,798 valid sequences and 15,277 operational taxonomic units (OTUs) from 32 samples were obtained by 454 tag amplicon pyrosequencing. The Shannon indices of the seawater samples ranged from 2.84 to 5.6 and the Shannon indices of the abalone intestine samples ranged from 1.2 to 5.12, which were much lower than those of seawater. The dominant phyla in seawater samples were Proteobacteria, Bacteroidetes, Fusobacteria, Cyanobacteria, etc. The dominant phyla in the abalone intestine varied greatly in different months. The dominant genera in the seawater of the cement culture ponds changed in different months, mainly Psychrilyobacter and Pseudoalteromonas. The dominant genera in seawater from the open sea vary considerably between months. The dominant genus of bacteria in the abalone intestine during the months when abalones are susceptible to disease is mainly Mycoplasma spp. Canonical correspondence analysis revealed that bacterial communities in seawater and the intestine responded differently to environmental variables, with similar microbiota in the same area. pH, dissolved oxygen concentration, and temperature were closely related to the samples from the sea area. Oxidation-reduction potential, salinity, phosphate, nitrate, and ammonia nitrogen concentrations were closely related to the water samples from the artificial pools. These findings may add significantly to our understanding of the complex interactions between microbiota and environmental variables in the abalone intestine as well as in the surrounding seawater.

Along the Pacific coast of the Baja California Peninsula (Mexico), abalone represents one of the most lucrative fisheries. As wild populations are currently depleted, abalone farm production aims to balance the decreasing populations with the increasing demand. The Mexican abalone aquaculture is almost entirely based on red abalone (Haliotis rufescens). However, the increasing frequency of extreme temperature events is hampering this activity. The use interspecific hybrids can potentially improve abalone culture, as species have differences in their thermal tolerance. Therefore, the hybrid progeny between H. rufescens (♀) and pink abalone H. corrugata (♂), a temperate and a warmer water abalone species, respectively, will naturally support higher temperature. To test this hypothesis, growth rate, mortality and metabolic rate of both pure (RR) and hybrid abalone (RP) were assessed under the H. rufescens' optimum (18 °C) and thermally stressed (22 °C) conditions. To unveil the molecular pathways involved in the heat response, transcriptional profiling of both crosses was also investigated. At high temperature, we observed constrained growth and survival in RR while RP showed a significant increase in both rates, supporting the improved performance of the hybrid compared. These results match with the transcriptional profiling of hybrids showing higher expression of genes involved in growth and calcification, whereas in the pure red progeny, the transcriptional profile was mainly associated with the regulation of necroptosis process. Our results may contribute to propose new management plans to increase farm abalone production in Baja California. [ABSTRACT FROM AUTHOR]

Macin is a family of antimicrobial peptides (AMPs) and is involved in the immune responses of marine mollusks. In the present study, a novel Mytimacin (denoted as Hd-mtmc 6) was identified from the small abalone Haliotis diversicolor by RNA-seq and RACE techniques. Hd-mtmc 6 contained a coding sequence of 243 bp and encoded 80 amino acids, with a putative peptide mytimacin 6 consisting of 61 amino acid residues. The mature peptide of Hdmtmc 6 exhibited typical characteristics of AMPs, including net positive charge (+4), higher hydrophobic residue ratio (37%), and lower molecular mass. Eight cysteines in the mature peptide formed four disulfide bond bridges (C1-C6, C2- C5, C3-C7, and C4-C8). Moreover, the presence of the macin domain, a threedimensional structure similar to that of hydramacin-1, and a phylogenetic relationship suggested that Hd-mtmc 6 could be a new member of the invertebrate macin family. In unchallenged abalone, the Hd-mtmc 6 transcript was expressed in all tested tissues and could be detected at different stages of embryonic development. Vibrio harveyi challenge caused a significant Hd-mtmc 6 transcripts upregulation within 2 - 6 h in the mantle and hepatopancreas. Our results suggested that Hd-mtmc 6 may be involved in innate immune responses of small abalone. Further investigations are required to confirm its antibacterial activity at the protein level. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effects of different softening methods on the texture and quality of abalones (Haliotis discus hannai × Diversicolor diversicolor). We monitored the hardness, meat weight, pH, size, and appearance from the sterilized abalones pre-treated with alkaline soaking and enzymatic injection/soaking, with either vacuum orbital shaking or ultrasonic processing. The hardness of the abalones was reduced by alkaline and enzymatic treatments, and combined vacuum orbital shaking or ultrasound treatment and this could increase their tendering effects. The softest abalone was obtained by bromelain comparing to papain injection, and the TVBN measurements indicated that the abalones remained in a fresh state under all treatments. Both enzymatic treatments showed a dose-dependent effects on hardness and pH of sterilized abalones. The abalones pre-treated with injecting enzyme exhibited significant softening effect than soaking method. Histological observation indicated that severe fracturing and non-uniform large spaces between muscle fibers were observed in the abalones injected with bromelain, and the abalones subjected to NaHCO3 soaking showed distorted muscle fibers and small uniform spaces. SDS-PAGE further indicated the decrease of paramyosin in the abalones injected with bromelain. Sensory evaluation using senior panelists without chewing difficulties indicated that NaHCO3 soaking before sterilization exhibited the highest overall acceptability, possibly because this method could slightly soften abalone foot while retaining its palatability. This study should benefit the food industry in terms of developing and processing food for senior citizens. [ABSTRACT FROM AUTHOR]

Growing demand for high-value seafood is fuelling provenance fraud, which threatens the sustainability of wild fisheries while posing biosecurity and human health risks. Here, we investigated carbon ( δ 13 O) isotopes in abalone shells ( δ sp.) to determine the production method and geographical provenance. Using X-ray diffraction and isotope ratio mass spectrometry, we found that shell mineralogy did not influence isotope values. Isotope values between wild and farmed sectors were statistically different, with 64% of individuals correctly classified as farmed or wild. Subsequently, we successfully distinguished the provenance of abalone collected from farms (with 83% of individuals correctly classified), as well as wild-caught abalone collected from four state jurisdictions (with 88% correctly classified). Carbon isotopes were strongly correlated to longitude, with both isotopes correlated to latitude. Overall, this study demonstrates the potential of isotopic fingerprints in gastropod shells to track the provenance of commercially valuable species.18 O) isotopes in abalone shells ( Haliotis sp.) to determine the production method and geographical provenance. Using X-ray diffraction and isotope ratio mass spectrometry, we found that shell mineralogy did not influence isotope values. Isotope values between wild and farmed sectors were statistically different, with 64% of individuals correctly classified as farmed or wild. Subsequently, we successfully distinguished the provenance of abalone collected from farms (with 83% of individuals correctly classified), as well as wild-caught abalone collected from four state jurisdictions (with 88% correctly classified). Carbon isotopes were strongly correlated to longitude, with both isotopes correlated to latitude. Overall, this study demonstrates the potential of isotopic fingerprints in gastropod shells to track the provenance of commercially valuable species., Competing Interests: We declare we have no competing interests., (© 2024 The Authors.)

Glutaredoxins (Grxs) are well-known oxidoreductases involved in a wide range of redox activities in organisms. In this study, two invertebrate Grxs (AbGrx1-like and AbGrx2) from disk abalone were identified and characterized in an effort to gain a deeper understanding into their immune and redox regulatory roles. Both AbGrxs share typical thioredoxin/Grx structures. AbGrx1-like and AbGrx2 were identified as monothiol and diothiol Grxs, respectively. AbGrxs were significantly expressed at the egg and 16-cell stage of early abalone development. Although the expression of both AbGrx s demonstrated similar patterns, the expression of AbGrx1-like was higher than AbGrx2 during development stages. In contrast, AbGrx2 expression was significantly higher than that of AbGrx1-like in adult tissues. Highest AbGrx1-like expression was observed in the hepatopancreas and digestive tract, while highest AbGrx2 expression was found in the gills, followed by the mantle, in healthy adult abalone tissues. The highest expression of AbGrx1-like was observed in the gills at 12 h and 6 h post injection (p.i) of Vibrio parahemolyticus and other stimulants, respectively. The highest expression of AbGrx2 in the gills were observed at 120 h, 6 h, 24 h, and 12 h post injection of V. parahaemolyticus , Listeria monocytogenes , Viral hemorrhagic septicemia virus, and Polyinosinic:polycytidylic acid, respectively. AbGrxs possessed significant 2-hydroxyethyl disulfide (HED) and dehydroascorbate (DHA) reduction activity, but AbGrx2 exhibited higher redox activity than AbGrx1-like. Altogether, our results suggest an important role of AbGrx1-like and AbGrx2 in redox homeostasis, as well as in the invertebrate immune defense system. Our findings will aid the development of new disease management strategies for this economically valuable species. • Grx1-like and Grx2 from Haliotis discus discus were characterized. • AbGrxs showed ubiquitous expression in early embryonic development stages of abalone. • AbGrx1-like and AbGrx2 exhibit the highest tissue-specific expression in hepatopancreas and gills, respectively. • AbGrxs in gills exhibit significant modulation for immune stimulations. • Recombinant AbGrxs displayed significant redox activity. [ABSTRACT FROM AUTHOR]

In Australia, commercially farmed greenlip abalone (Haliotis laevigata Donovan), fed formulated diets display a faint lip and dark foot colour in comparison with wild abalone. This study evaluates the impact of macroalgal diets and water temperatures on the colour and tissue pigment deposition in farmed greenlip abalone. Three diets are (a) fresh Ulva sp., (b) a commercial diet and (c) a formulated diet of 30% of dried Ulva sp. meal supplement were used to feed 3‐year‐old greenlip abalone at either 22 or 26°C for 38 days. Abalone fed 30% dried Ulva sp. meal supplement had significantly higher the shell colour saturation than those fed fresh Ulva sp. The lip colour was deeper in abalone fed fresh Ulva sp. and was significantly more pronounced than those fed the diet containing 30% Ulva sp. meal. Abalone at 22°C had a significantly higher lip colour saturation value than those at 26°C. The foot of abalone fed fresh Ulva sp. was light gold, whereas abalone fed the 30% Ulva sp. meal or the commercial diet had a dark brown foot at 22°C. The foot colour was paler in abalone at 26°C than at 22°C. The content of β‐carotene was significantly higher in abalone fed fresh Ulva sp. than those fed the other diets. Abalone contained a higher amount of β‐carotene at 22°C than at 26°C. This study indicates that high water temperatures make foot colour paler and the fresh Ulva sp. diet can make the foot colour lighter at 22°C. [ABSTRACT FROM AUTHOR]

In recent years, suboptimal environmental conditions have been frequently reported to negatively impact on aquaculture organisms. Salinity is an important environmental factor, and its fluctuation will affect survival, growth and, potentially, the meat quality of the organisms with narrow salt tolerance cultured in coastal and inner bay. The aim of the study was to ascertain and report the influence of sub‐low salinity (28 and 30) on the production traits and nutrient composition of the Pacific abalone Haliotis discus hannai (DD), and two of its hybrids (DF and SD). In view of this, 360 abalones were subjected to four salinity levels (28, 30, 32 and 34) for ninety days. The data showed that the weight gain and the specific growth rates in wet weight between the groups followed the trend of DF > SD > DD. DF recorded the highest meat yield, which was significantly higher than SD and DD (p <.05). The sub‐low salinities tested did not influence moisture content, crude protein, total lipid and total carbohydrate (p >.05). Whilst lipid levels were fairly higher in SD and DF than in DD, at sub‐low salinities, the opposite was true for carbohydrate content. Total minerals (ash), however, were influenced by salinity (p <.05). Individuals reared at 28 significantly differed from those of the other three treatments, but there was no significant difference between the groups (p >.05). Further analysis showed sodium and potassium as the predominant minerals—with a higher concentration of sodium at higher salinities, though no significant difference was found between individuals treated at 30, 32 and 34. Zinc was the only mineral not affected by salinity (p >.05), and the accumulation of discrete minerals by the species significantly differed from one mineral to the other and proved to be species‐specific. Notwithstanding, SD demonstrated superior content of most essential minerals over DF and DD. The results in this paper infer that the Pacific abalone and its hybrids could maintain good meat quality and survival under a range of 28–34 of salinity, promoting the growth of cultured abalone under the sub‐low salinity of 28. [ABSTRACT FROM AUTHOR]

Energy budgets were developed for greenlip abalone (Haliotis laevigata) under different feeding scenarios to predict growth, metabolic and waste outputs. The energy budgets of abalone fed live macroalgae (Ulva sp. or Gracilaria cliftonii) and an equal mix of those two macroalgae species with and without nutrient enrichment, or one of three control formulated commercial diets, at 22°C for 93 days were investigated. Among non‐enriched algal treatments, abalone fed G. cliftonii and mixed diet treatments had significantly higher ingested feed energy and absorbed energy than those fed Ulva sp. Abalone fed non‐enriched G. cliftonii invested significantly more energy into somatic growth than those fed Ulva sp. and the mixed diet treatment. For diets with nutrient enrichment, ingested feed energy and absorbed energy rate of abalone fed G. cliftonii and mixed diet treatments were significantly higher than those fed Ulva sp. Nutrient enrichment increased crude protein in live macroalgae, and ammonia excretion energy rate was higher for abalone fed enriched macroalgae compared to non‐enriched. Abalone fed the control commercial diets spent more energy in all components compared to those fed the live macroalgae treatments. The major component of the energy budgets in abalone fed the commercial diets and live macroalgae diets was somatic growth energy, ranging from 25.5% to 37.7% of ingested feed energy, except for abalone fed live Ulva sp. where the major component was respiration energy (38.5%). Overall, abalone fed the formulated diets or live non‐enriched G. cliftonii could increase ingested feed energy, absorbed energy and somatic growth energy. [ABSTRACT FROM AUTHOR]

A 240-day feeding trial was conducted to investigate the effects of dietary vitamin C on growth performance, anti-oxidative response, and fatty acid composition of juvenile abalone Haliotis discus hannai Ino (initial body weight: 0.93±0.00 g). Three semi-purified experimental diets were formulated containing 0.00, 94.52, and 9 649.58 mg/kg of vitamin C supplied as L-ascorbyl-2-monophosphate. The results show that there was no significant difference in weight gain ratio, daily increment in shell length, and survival rate among the three treatments. Adding dietary vitamin C (9 649.58 mg/kg) significantly increased the activities of superoxide dismutase (SOD), glutathine peroxidase (GPX), glitathione-S-transferase (GST), glutathione reductase (GR), alkaline phosphatase (AKP), and lysozyme in viscera (P<0.05). In muscle, activities of phenoloxidase, catalase, SOD, GST, GR, and AKP were increased in the treatment with 9 649.58 mg/kg of dietary vitamin C (P<0.05). The highest concentrations of ascorbic acid in viscera and muscle were found in the group with 9 649.58 mg/kg of dietary vitamin C (P<0.05). The contents of crude protein and crude lipid in the soft body were significantly increased in the 9 649.58 mg/kg group (P<0.05). Dietary vitamin C supplementation significantly decreased the contents of saturated fatty acids (14:0, 16:0, and 18:0), and increased the composition of 18:2n-6 and 22:6n-3 in the soft body of abalone (P<0.05). Therefore, although there were no significant effects on the growth performance, dietary vitamin C supplementation improved the anti-oxidation and immune responses, increased specific unsaturated fatty acid (i.e., 16:1, 18:1n-7, 18:1n-9, 18:2n-6 and 22:6n-3), and decreased specific saturated fatty acid (i.e., 14:0, 16:0 and 18:0) contents in the soft body of abalone. [ABSTRACT FROM AUTHOR]

The scuticociliatid ciliates Ancistrum haliotis and A. crassum are parasites that may cause high mortality in the cultured abalone Haliotis spp. and the bivalve Ruditapes philippinarum. Traditional identification with silver staining methods is hampered by their morphological similarities to closely related species and the complicated procedures of morphological analysis. We designed two SSU rRNA-targeted oligonucleotide probes labeled with a fluorochrome, and optimized the fluorescence in situ hybridization (FISH) protocols for identification of A. halioti and A. crassum, respectively. The assays resulted in a clear identification by strong fluorescence signals from the oligonucleotide probes. The method can be used for quick and accurate quantitative analysis of A. haliotis and A. crassum infections on host molluscs. [ABSTRACT FROM AUTHOR]

Members of lactic acid bacteria (LAB) have been well-known for probiotic agents owing to their ability to produce diverse beneficial compounds for cultured species, as well as for having a status of generally recognized as safe microorganisms. Considering these facts, the current study investigated the presence of cultivable LAB associated with the gastrointestinal tracts (GIT) of hybrid abalone (Haliotis laevigata x H. rubra Brown 1992) at various life stages (larvae, juvenile, and adult), and screened them for their probiotic properties. GITs of 90 hybrid abalone (30 larvae, 30 juveniles, and 30 adult stages) were dissected out aseptically and then inoculated into de Man Rogosa Sharp (MRS) broth and agar. The result revealed that no LAB was isolated from the GITs of abalone at the larval stage. LAB were firstly recorded at the juvenile stage (44 isolates) and the adult stage (49 isolates). Based on partial sequences of the 16S rRNA gene, the 44 LAB in the juvenile stage were identified as five genera and belonged to 10 ribotypes. While the 49 LAB isolates from the adult stage were identified as three genera and belonged to eight ribotypes. Of the 93 LAB, five strains which were Enterococcus faecium MA002, Enterococcus lactis MA056, Leuconostoc mesenteroides MA064, Enterococcus lactis MA068, and Enterococcus lactis MA084, exhibited antagonistic activities against bacterial pathogens (Vibrio alginolyticus and Listeria monocytogenes). The five LAB strains did not show any hemolytic activity, possibly indicating that they were non-pathogen. These results confirmed that LAB colonized the intestinal tract of abalone at juvenile and adult stages and were capable of producing antimicrobial compounds. Acknowledging the presence of indigenous LAB in GITs of abalone, a prebiotic application can be considered for another strategy to modify the healthy microbiome of abalone.

Gills are important organs for aquatic invertebrates because they harbor chemosynthetic bacteria, which fix inorganic carbon and/or nitrogen and provide their hosts with organic compounds. Nevertheless, in contrast to the intensive researches related to the gut microbiota, much is still needed to further understand the microbiota within the gills of invertebrates. Using abalones as a model, we investigated the community structure of microbes associated with the gills of these invertebrates using next-generation sequencing. Molecular identification of representative bacterial sequences was performed using cloning, nested PCR and fluorescence in situ hybridization (FISH) analysis with specific primers or probes. We examined three abalone species, namely Haliotis gigantea, H. discus and H. diversicolor using seawater and stones as controls. Microbiome analysis suggested that the gills of all three abalones had the unclassified Spirochaetaceae (one OTU, 15.7 ± 0.04%) and Mycoplasma sp. (one OTU, 9.1 ± 0.03%) as the core microbes. In most libraries from the gills of H. gigantea, however, a previously unknown epsilonproteobacterium species (one OTU) was considered as the dominant bacterium, which accounted for 62.2% of the relative abundance. The epsilonproteobacterium was only detected in the gills of H. diversicolor at 0.2% and not in H. discus suggesting that it may be unique to H. gigantea. Phylogenetic analysis performed using a near full-length 16S rRNA gene placed the uncultured epsilonproteobacterium species at the root of the family Helicobacteraceae. Interestingly, the uncultured epsilonproteobacterium was commonly detected from gill tissue rather than from the gut and foot tissues using a nested PCR assay with uncultured epsilonproteobacterium-specific primers. FISH analysis with the uncultured epsilonproteobacterium-specific probe revealed that probe-reactive cells in H. gigantea had a coccus-like morphology and formed microcolonies on gill tissue. This is the first report to show that epsilonproteobacterium has the potential to be a dominant species in the gills of the coastal gastropod, H. gigantea.

Molluscs are major contributors to the international and Australian aquaculture industries, however, their immune systems remain poorly understood due to limited access to draft genomes and evidence of divergences from model organisms. As invertebrates, molluscs lack adaptive immune systems or ‘memory’, and rely solely on innate immunity for antimicrobial defence. Hemolymph, the circulatory fluid of invertebrates, contains hemocytes which secrete effector molecules with immune regulatory functions. Interactions between mollusc effector molecules and bacterial and fungal pathogens have been well documented, however, there is limited knowledge of their roles against viruses, which cause high mortality and significant production losses in these species. Of the major effector molecules, only the direct acting protein dicer-2 and the antimicrobial peptides (AMPs) hemocyanin and myticin-C have shown antiviral activity. A better understanding of these effector molecules may allow for the manipulation of mollusc proteomes to enhance antiviral and overall antimicrobial defence to prevent future outbreaks and minimize economic outbreaks. Moreover, effector molecule research may yield the description and production of novel antimicrobial treatments for a broad host range of animal species.

Sexual selection can explain the rapid evolution of fertilization proteins, yet sperm proteins evolve rapidly even if not directly involved in fertilization. In the marine mollusk abalone, sperm secrete enormous quantities of two rapidly evolving proteins, lysin and sp18, that are stored at nearly molar concentrations. We demonstrate that this extraordinary packaging is achieved by associating into Fuzzy Interacting Transient Zwitterion (FITZ) complexes upon binding the intrinsically disordered FITZ Anionic Partner (FITZAP). FITZ complexes form at intracellular ionic strengths and, upon exocytosis into seawater, lysin and sp18 are dispersed to drive fertilization. NMR analyses revealed that lysin uses a common molecular interface to bind both FITZAP and its egg receptor VERL. As sexual selection alters the lysin-VERL interface, FITZAP coevolves rapidly to maintain lysin binding. FITZAP-lysin interactions exhibit a similar species-specificity as lysin-VERL interactions. Thus, tethered molecular arms races driven by sexual selection can generally explain rapid sperm protein evolution.

In central California, the role of algal assemblages on the recruitment of the canopy producing annual kelp Nereocystis luetkeana was examined by experimentally manipulating canopy and understory algae within 1) a Macrocysits bed and 2) a Nereocystis bed. Nereocystis reproductive material was introduced in some plots to examine the role of dispersal distance on recruitment. Nereocystis recruitment at both sites was significantly higher during spring compared to recruitment observed later in the study. Recruitment continued throughout the fall, however, suggesting a broad recruitment window. Recruitment success increased dramatically when understory algae were removed. Presence of a canopy (Nereocystis or Macrocystis) did not affect Nereocystis recruitment, suggesting that Nereocystis was not directly competitively inferior to Macrocystis. Greater recruitment was observed in areas seeded with Nereocystis propagules. Ultimately, recruitment of Nereocystis was controlled by understory algal assemblages and by the relatively short dispersal distance of its propagules. Additionally, the broad recruitment window for Nereocystis described here suggests that summer recruits can contribute to population resilience to late spring disturbances. This study indicates that given sufficient disturbance to the benthos and ample propagule supply, Nereocystis should be able to recruit and colonize new areas, regardless of the presence of Macrocystis.

Abstract Background Holobionts have a digestive microbiota with catabolic abilities allowing the degradation of complex dietary compounds for the host. In terrestrial herbivores, the digestive microbiota is known to degrade complex polysaccharides from land plants while in marine herbivores, the digestive microbiota is poorly characterized. Most of the latter are generalists and consume red, green, and brown macroalgae, three distinct lineages characterized by a specific composition in complex polysaccharides, which represent half of their biomass. Subsequently, each macroalga features a specific epiphytic microbiota, and the digestive microbiota of marine herbivores is expected to vary with a monospecific algal diet. We investigated the effect of four monospecific diets (Palmaria palmata, Ulva lactuca, Saccharina latissima, Laminaria digitata) on the composition and specificity of the digestive microbiota of a generalist marine herbivore, the abalone, farmed in a temperate coastal area over a year. The microbiota from the abalone digestive gland was sampled every 2 months and explored using metabarcoding. Results Diversity and multivariate analyses showed that patterns of the microbiota were significantly linked to seasonal variations of contextual parameters but not directly to a specific algal diet. Three core genera: Psychrilyobacter, Mycoplasma, and Vibrio constantly dominated the microbiota in the abalone digestive gland. Additionally, a less abundant and diet-specific core microbiota featured genera representing aerobic primary degraders of algal polysaccharides. Conclusions This study highlights the establishment of a persistent core microbiota in the digestive gland of the abalone since its juvenile state and the presence of a less abundant and diet-specific core community. While composed of different microbial taxa compared to terrestrial herbivores, the digestive gland constitutes a particular niche in the abalone holobiont, where bacteria (i) may cooperate to degrade algal polysaccharides to products assimilable by the host or (ii) may have acquired these functions through gene transfer from the aerobic algal microbiota.

An abalone is a group of marine molluscs that have high economic value. To increase abalone production, such cultivation needs to be done considering that abalone production still dominating. However, there are still obstacles in the cultivation which is the high mortality rates on the grading process of juvenile abalone. The fatality occurs due to the traditional grading process by gouging abalone to separate abalone that is attached to the substrate. The use of ethanol as an anesthetic material is expected to minimize the mortality and increase the survival rate of abalone. In this study, the use of ethanol by 30 ml/L as an anesthetic material can separate the abalone from its substrate 447.67 seconds faster than the dose of 10 ml/L. However, the 30 ml/L dose also showed the lowest survival rate of 86.67%. The best recovery test is at 10 ml/L with the fastest recovery time of 143.33 seconds which has a high survival rate of 98.33%. The success of anesthesia by using ethanol in this study can also be done in the grading process of abalone seed and can minimize death due to the traditional grading process.

Texture of muscle food is dependent on the gelation properties of myofibrillar protein. Defining the performance of myofibrillar protein during gelation is beneficial for maintaining quality and developing muscle food. The myofibrillar protein from abalone muscle (AMP) was extracted and the gel-forming ability was investigated. The lowest protein solubility of AMP in distilled water was obtained at pH 5.5, but shifted to a lower pH value by ionic strength. The breaking force and deformation of AMP gel formed at pH 7.0 were 48.00 g and 27.70 mm, respectively, but they could not be detected at pH 5.0 and pH 5.5 due to the low gel-forming ability. Scanning electron microscopy data showed that a coarse and disorder gel containing clusters of agglomerates was observed at pH 5.0 and pH 5.5, but gradual compact network structure was observed in the gel formed at increasing pH. The glass transition temperature (Tg) of AMP gel formed at pH 5.5 was higher than that of AMP, and the Tg of AMP gel was increased with increasing the pH of gel-forming solution. It was found that the unfolding of tertiary structure of AMP at pH 7.0 was easier than that at pH 5.5 through the result of infrared spectra. We therefore conclude that both the solubility and gel-forming ability of AMP are pH dependent.

Abalone (Haliotis discus hannai) has high nutritional value and market demand. However, it is generally sold as a raw product, which suffers from lengthy preparation, low commercial value, and a short shelf life. To address these problems, we processed abalone as a home meal replacement (HMR) product using superheated steam and quick freezing technology. Response surface methodology was used to optimize the roasting process. A test HMR product was produced by mixing roasted abalone with honey butter sauce at a ratio of 70:30 (w/w), then evaluated for its physicochemical, biological, and nutritional characteristics and shelf life. Roasting abalone at 220 °C for 2 min resulted in high scores for hardness and overall acceptance. The roasting process successfully maintained the chemical characteristics of abalone, including pH, volatile basic nitrogen, and thiobarbituric acid-reactive substances. The sensory characteristics of the test HMR product were maintained using quick freezing methods. Moreover, nutritional analysis revealed that the test HMR product contained macro- and micronutrients, amino acids, and fatty acids, which could contribute to meeting daily nutritional needs. The estimated shelf life of the product was 30 months. Therefore, this study successfully developed a high-quality HMR product containing abalone.

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. [ABSTRACT FROM AUTHOR]

The abalone industry has suffered immense economic losses due to the occurrence of harmful algal blooms (HABs). Among the methods for mitigating HABs, modified clay is considered the most promising strategy and has been successfully used for field applications in many countries, and its environmental effects have become a subject of global concern. The effects of modified clay on the survival, growth, nutritional quality, and oxidative stress indicators of abalone were studied based on both laboratory and field experiments. The results showed that modified clay at 3–10 times the concentrations used for HAB treatment did not affect the survival of abalone. During the laboratory experiments, the increases in abalone shell length and weight nonsignificantly decreased with increasing concentrations of modified clay at 1–15 d, whereas the weight of abalone in the experimental groups increased rapidly during the recovery period at 16–30 d. The growth and nutrition qualities of abalone in field experiments showed negligible differences between the control and experimental groups. Catalase (CAT) activity in the hepatopancreas and superoxide dismutase (SOD) activity in the gills were significantly affected by certain concentrations of modified clay at individual time points, whereas the malondialdehyde (MDA) content decreased in all experimental groups within 96 h. The removal of bacteria and the mitigation of water quality decline were among the effects of modified clay that contributed to the decrease in MDA content. The present study showed that modified clay had no obvious adverse effects on the survival, growth, quality, or oxidative stress indicators of abalone at the experimental concentrations, thus providing a reference for the field application of modified clay in typical aquaculture areas. Environ Toxicol Chem 2020;39:2065–2075. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Ocean warming induced by high CO2 emission is expected to change the behavior of many marine poikilotherms. During the day, abalones take shelter under rocks or in crevices from which they emerge to forage in the evening. In this study, we explored the effect of changing seawater temperature on the foraging and hiding behaviors of the juvenile Pacific abalone Haliotis discus hannai. First, we tested whether their hiding behavior in response to light differs depending on the temperature (11°C, 14°C, and 17°C) when only artificial shelter was provided. We observed that the abalones hid under the shelter much faster at 17°C than at 11°C. Second, we tested whether their hiding and foraging behaviors changed in response to increasing temperature when both food and shelter were provided. At high water temperature (17°C), abalones emerged more quickly than at low water temperature (11°C), and the total number of feeding abalones was higher at high temperature than that at low temperature. However, the hiding speed in response to light in the morning was not significantly different among different temperatures. These results suggest that although the basic response to a single stimulus (i.e., light or food) was faster at higher temperatures than at lower temperatures, abalones may increase their boldness under higher temperatures when deciding whether to feed or hide. [ABSTRACT FROM AUTHOR]

Effective fishery management strategies should be based on stock delimitation and knowledge of the spatial scale at which species are distributed. However, a mismatch often occurs between biological and management units of fishery resources. The green abalone (Haliotis fulgens) supports an important artisanal fishery in the west coast of the Baja California Peninsula (BCP), Mexico, which has shown a declining tendency despite the several management measures. Thus, the aim of this study was to characterize the spatial patterns of neutral genomic variation of green abalone along the BCP to test whether the genomic structure patterns support the current green abalone management areas. To test this hypothesis, a set of 2,170 putative neutral single nucleotide polymorphisms discovered by a double digest restriction-site associated DNA approach was used on 10 locations along the BCP. The results revealed a population structure with three putative groups: Guadalupe Island and northern and southern BCP locations. The contemporary gene flow might be explained by local oceanographic features, where it is bidirectional within the southern region but with a predominant southward flow from the northern region. These findings indicated that the administrative areas did not match the biological units of H. fulgens fishery; hence, the stock assessment and management areas should be revised. [ABSTRACT FROM AUTHOR]

An experiment was conducted to develop a land-based recirculating integrated multi-trophic aquaculture (IMTA) system using a combination of the Omani abalone (Haliotis mariae) and Asian seabass (Lates calcarifer) as fed species, brown mussel (Perna perna) and seaweed (Ulva fasciata) as extractive species. Specifically, this study was carried out to determine the optimal seabass density (20, 40 and 60 individuals per 500-liter tank) on water quality, growth and survival of the cultured species in the system. Sampling of all species was done every two weeks to check their growth. Water samples were taken every two weeks for analysis of ammonia, nitrite, nitrate, phosphate, and silicate. Measurements of temperature, dissolved oxygen and salinity were done daily. Growth of abalone and mussels were higher in fish densities of 20/tank and 40/tank, respectively, while growth and survival of seabass were not significantly different between densities. Biomass of seaweeds decreased during the experiment period. Temperature, dissolved oxygen and salinity were within optimum levels. Ammonia levels decreased as nitrite increased but in some cases it remained high while nitrates did not increase, indicating that nitrites were not converted to nitrates most likely due to the lack of efficient bio-filtration in the mussel tanks. [ABSTRACT FROM AUTHOR]

Mycotoxins are toxic secondary metabolites produced by various filamentous fungi, of which Fusarium, Aspergillus and Penicillium are the three main genera. Fusarium verticillioides is one of the most dominant toxigenic fungal species, associated with fumonisin contamination in grain-based feeds, such as compound abalone feed. Mycotoxin production is influenced by temperature and available nutrients. In this study the aims were: to determine if abalone feed as growth substrate favours mycotoxin production for toxigenic fungi; to determine the most effective temperature for fumonisin production by F. verticillioides on abalone feed; and to assess the effect of the aquatic environment on fumonisin-contaminated abalone feed. A total of 93 fungal isolates were inoculated onto abalone feed, including species belonging to the genera Fusarium, Aspergillus and Penicillium. Feed inoculated with F. verticillioides were incubated at two different temperatures and fumonisin-contaminated feed was submerged into seawater for 24 h. Results showed that mycotoxins were produced when abalone feed was inoculated with toxigenic fungi, and that F. verticillioides produced higher concentrations of fumonisins at a lower temperature. Submerging fumonisin-contaminated feed in seawater showed that this toxin leached into the seawater, lowering the risk of fumonisins to be consumed by abalone. [ABSTRACT FROM AUTHOR]

The South African abalone Haliotis midae is a commercially important species farmed at high densities in land-based aquaculture systems. Disease outbreaks have had a severe financial impact on the abalone industry yet the molecular mechanisms underlying the immune response of H. midae remain obscure. In this study, a comparative shotgun proteomics approach using iTRAQ coupled with LC-MS/MS was employed to investigate H. midae proteome changes in response to Vibrio anguillarum challenge. A total of 118 non-redundant, unique haemocyte proteins were identified and quantified, with 16 proteins significantly regulated. Hierarchical clustering and pathway analysis uncovered a coordinated response dominated by calcium and cAMP signalling via activation of MAPK cascades. Early up-regulated biological processes involve phagocytosis, nitric oxide production and ATP-synthesis, whilst down-regulated responses were predominantly involved in the regulation of apoptosis. The late up-regulated response involved protein kinase activity and detoxification processes. Expression of selected proteins was validated by Western blot. A putative allograft inflammatory factor-1 protein was further selected to establish its functional molecular role in haemocytes. Confocal imaging revealed that allograft inflammatory factor-1 regulates phagocytosis via a functional interaction with filamentous actin. This is the first time a high-throughput proteomics approach has been used to investigate the immune response of H. midae. • Comparative shotgun proteomics was used to investigate H. midae immune changes. • 118 unique haemocyte proteins were identified by iTRAQ and LC-MS/MS. • Early upregulation involved phagocytosis, endocytosis and ATP-synthesis. • The late immune response involved detoxification processes. • Allograft inflammatory factor-1 regulates phagocytosis and interacts with F-actin. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA) and its subsequent changes in seawater carbonate chemistry are threatening the survival of calcifying organisms. Due to their use of calcium carbonate to build their shells, marine molluscs are particularly vulnerable. This study investigated the effect of CO2-induced OA on adult European abalone (Haliotis tuberculata) using a multi-parameter approach. Biological (survival, growth), physiological (pHT of haemolymph, phagocytosis, metabolism, gene expression), and structural responses (shell strength, nano-indentation measurements, Scanning electron microscopy imaging of microstructure) were evaluated throughout a 5-month exposure to ambient (8.0) and low (7.7) pH conditions. During the first 2 months, the haemolymph pH was reduced, indicating that abalone do not compensate for the pH decrease of their internal fluid. Overall metabolism and immune status were not affected, suggesting that abalone maintain their vital functions when facing OA. However, after 4 months of exposure, adverse effects on shell growth, calcification, microstructure, and resistance were highlighted, whereas the haemolymph pH was compensated. Significant reduction in shell mechanical properties was revealed at pH 7.7, suggesting that OA altered the biomineral architecture leading to a more fragile shell. It is concluded that under lower pH, abalone metabolism is maintained at a cost to growth and shell integrity. This may impact both abalone ecology and aquaculture. [ABSTRACT FROM AUTHOR]

In lecithotrophic larvae, egg yolk nutrients are essential for development. Although yolk proteins and lipids are the major nutrient sources for most animal embryos and larvae, the contribution of carbohydrates to development has been less understood. In this study, we assessed glucose and glycogen metabolism in developing Pacific abalone, a marine gastropod mollusc caught and cultured in east Asia. We found that glucose and glycogen content gradually elevated in developing abalone larvae, and coincident expression increases of gluconeogenic genes and glycogen synthase suggested abalone larvae had activated gluconeogenesis and glycogenesis during this stage. At settling, however, glycogen sharply decreased, with concomitant increases in glucose content and expression of Pyg and G6pc, suggesting the settling larvae had enhanced glycogen conversion to glucose. A liquid chromatography-mass spectrometry (LC/MS)-based metabolomic approach that detected intermediates of these pathways further supported active metabolism of glycogen. Immunofluorescence staining and in situ hybridization suggested the digestive gland has an important role as glycogen storage tissue during settlement, while many other tissues also showed a capacity to metabolize glycogen. Finally, inhibition of glycolysis affected survival of the settling veliger larvae, revealing that glucose is, indeed, an important nutrient source in settling larvae. Our results suggest glucose and glycogen are required for proper energy balance in developing abalone and especially impact survival during settling. [ABSTRACT FROM AUTHOR]

The potential of enriched Ulva pertusa meal as feed ingredient in abalone juveniles, Haliotis asinina was evaluated. Four isonitrogenous and isolipidic diets were formulated which contain 27% protein and 5% lipid. Enriched U. pertusa meal replaced 0% (control), 10%, 20%, and 30% of protein from fish and soybean meals in the formulated diets. Thirty randomly selected abalone juveniles with average weight and shell length of 0.45 g ± 0.01 and 12.71 mm ± 0.01, respectively, were placed in each of the twelve 60-L oval fiberglass tanks equipped with a flow-through seawater system. Abalone were given diets at 3–5% body weight daily for 120 days in three replicate samples. Results showed no significant differences (p > 0.05) in percent weight gain, shell length, specific growth rate, feed conversion ratio, and protein efficiency ratio even up to 30% replacement level. Apparent dry matter digestibility of U. pertusa meal in abalone diet was 92%. Crude protein content of the abalone fed diets 1 (10% enriched U. pertusa meal) and 3 (30% enriched U. pertusa meal) was significantly (p < 0.05) higher than those fed on basal diet. Enriched U. pertusa meal can partially replace fish and soybean meals as protein source in formulated diets for abalone, Haliotis asinina juveniles. [ABSTRACT FROM AUTHOR]

This study tests the very general hypothesis that field fertilization success in red abalone is a predictable function of the hydrodynamic regime, and the density, sex ratio and spacing of animals within aggregations.Project Goals and Objectives (1) To determine the hydrodynamic mechanisms that facilitate fertilization of abalone inhabiting coastal waters; (2) To establish the optimal adult density, spacing and sex ratio to maximize fertilization success within a given flow regime; (3) To identify optimal field environments for transplanting or out-planting abalone aggregations, as well as natural abalone distributions that likely experience little or no reproductive success.

The objectives of the project were to create practical quantitative tools to address applied fishery management and marine conservation problems for California's abalone populations. We accomplished both goals during this project.

Hypothesis: Quantitative real-time PCR can be used to quantify loads of the WS rickettsial bacterium (infection intensity) in abalone.Hypothesis: Juvenile black abalone recruiting on the California Channel Islands are more resistant to WS than are black abalone in northern Central California that have not experienced high disease (WS) selection pressure.NOTE: only abstract of study available at this time pending publication of papers. For further information, please contact Carolyn S. Friedman (carolynf@u.washington.edu) or Glenn VanBlaricom (glennvb@u.washington.edu ).

(1) Red algae and kelp can be effectively cultivated in Monterey Harbor and harvested as abalone feed. (2) Mixed diets are superior to all kelp diets in enhancing farmed abalone marketability (growth and shell color) (3) Seaweed culture can sustain a small to moderately-sized California abalone farm.

The population growth rates of benthic broadcast-spawning species may be limited at low densities due to extreme reductions in fertilization rates. I investigated the influence of aggregation characteristics on the low-density population dynamics by incorporating aggregation-influenced fecundity estimates into a demographic matrix model for both pink (Haliotis corrugata) and red abalone (H. rufescens). I measured aggregation-level characteristics in populations representing a broad range of densities and spatial dispersions in order to characterize the relationships between population density, nearest-neighbor distances, and aggregation sizes.Average aggregation sizes were strongly correlated with population density density, such that lower-density populations contained smaller aggregations. The relationship between nearest-neighbor distances and population density was nonlinear, such that distances increased rapidly as the population density decreased below a threshold level. The effect of aggregation size on fecundity translates into a rapid decline in population growth below a threshold average aggregation size. The magnitude of the depensation effect may be amplified when additional factors influencing fertilization success (i.e. nearest neighbor distances) are considered.The results of a four-year study of a pink abalone population near San Diego, California, indicate that the population is partially recovered as defined by the California Department of Fish and Game Abalone Recovery and Management Plan. However, theaverage population growth rate estimate was 1.070 yr-1 for high fertilization success conditions, and 0.902 yr-1 for low fertilization success conditions. Based on the average nearest-neighbor distances measured in this population (>5 meters), the expected fertilization success rate is low. This finding suggests that, in the absence of an external larval supply, this population may be declining.This work provides important baseline information on aggregation characteristics that was previously unavailable for the California populations of pink and red abalone, and wavy turban snails (Megastraea undosa). The matrix models illustrate how the aggregation-level characteristics may be incorporated into a formal population model in order to predict the critical aggregation size for that population. The results may be used to review the recovery of abalone stocks and to analyze the effectiveness of future management and recovery schemes.

[Display omitted] • Several histological factors correlate with the growth of Haliotis iris. • Poor nutrition correlates with poor growth and ceroid accumulation. • Prevalence of birefringent kidney stones was higher in the slow-growing population. • Histological surveying of various tissues provided insight into the health of H. iris. The black-foot abalone (pāua), Haliotis iris , is a unique and valuable species to New Zealand with cultural importance for Māori. Abalone are marine gastropods that can display a high level of phenotypic variation, including slow-growing or 'stunted' variants. This investigation focused on identifying factors that are associated with growth performance, with particular interest in the slow-growing variants. Tissue alterations in H. iris were examined using histopathological techniques, in relation to growth performance, contrasting populations classified by commercial harvesters as 'stunted' (i.e., slow-growing) and 'non-stunted' (i.e., fast-growing) from four sites around the Chatham Islands (New Zealand). Ten adults and 10 sub-adults were collected from each of the four sites and prepared for histological assessment of condition, tissue alterations, presence of food and presence of parasites. The gut epithelium connective tissue, digestive gland, gill lamellae and right kidney tissues all displayed signs of structural differences between the slow-growing and fast-growing populations. Overall, several factors appear to be correlated to growth performance. The individuals from slow-growing populations were observed to have more degraded macroalgal fragments in the midgut, increased numbers of ceroid granules in multiple tissues, as well as increased prevalence of birefringent mineral crystals and haplosporidian-like parasites in the right kidney. The histopathological approaches presented here complement anecdotal field observations of reduced seaweed availability and increased sand incursion at slow-growing sites, while providing an insight into the health of individual abalone and sub-populations. The approaches described here will ultimately help elucidate the drivers behind variable growth performance which, in turn, supports fisheries management decisions and future surveillance programs. [ABSTRACT FROM AUTHOR]

Abalones are a group of economically important species of mollusks that represent a source of high-quality protein. China accounts for 90% of the world's abalone production, and make a significant contribution to the aquaculture industry's economic value. With the increasing scale of abalone farming, problems such as the degradation of germplasm resources and a reduced ability to resist environmental changes and stresses have become increasingly prominent. The hybrid breeding technique has significantly ameliorated this situation. The distant hybrid species H. discus hannai ♀ × H. fulgens ♂ (the Lvpan abalone) shows significant heterosis in terms of growth and stress resistance. However, our knowledge of the cytogenetics and molecular mechanisms of heterosis in the hybrid abalone remains limited. In this study, we found significant non-transcribed spacer (NTS) variation of 5S rDNA gene among H. discus hannai , H. fulgens , and the Lvpan abalone, with five, two, and four types of NTSs identified, respectively. These NTSs exhibited genomic polymorphisms within and between species, making them reliable markers for species identification. Furthermore, the sequence alignment of NTSs and genomic resequencing analysis indicated that the hybrid abalone was biased toward H. discus hannai , suggesting a maternal effect. Moreover, numerous mutation sites that were identified only in the hybrid abalone potentially contributed to heterosis. This study provides a valuable molecular data reference for future research on distant hybridization and contributes to a better understanding of the molecular mechanisms underlying heterosis in mollusks. • Variations in the 5S rDNA gene can be used for interspecific identification. • Nucleotide mutations detected in Lvpan abalone potentially contribute to heterosis. • Comparison of variation suggests the presence of maternal effects in Lvpan abalone. [ABSTRACT FROM AUTHOR]

A 93-day growth trial was performed to evaluate the influences of graded dietary EPA levels (0.03% (control group), 0.24%, 0.63%, 1.07%, 1.72% and 2.25%) on the growth performance, immunity and heat tolerance of juvenile abalone Haliotis discus hannai with a mean initial weight of 4.15 ± 0.18 g. After the feeding trial, the findings found that the highest weight gain rate (WGR) belonged to the groups fed with 0.63% ∼ 1.72% of dietary EPA (P < 0.05). The lowest feed conversion ratio was distinguished in the groups with 0.63% ∼ 1.07% of dietary EPA (P < 0.05). Also, EPA supplementation in abalone feed increased the content of crude lipid in the soft body and the activity of lipase in the intestine (P < 0.05). The total antioxidative capacity increased when dietary EPA levels rose from 0.03% to 1.07%, and then decreased (P < 0.05). Furthermore, compared to the control group, the 0.24% and 0.24% ∼ 0.63% of dietary EPA significantly down-regulated the mRNA levels of IκB kinase and kelch-like ECH-associated protein 1, respectively (P < 0.05). However, nuclear factor-κB and interleukin 1 receptor-associated kinase 4 genes expression in the digestive gland were significantly up-regulated by the use of 1.72% and 2.25% of EPA in diet (P < 0.05). The mRNA levels of tumor necrosis factor α and interleukin 16 were significantly up-regulated by the 2.25% of dietary EPA (P < 0.05). The 1.72% of dietary EPA significantly increased the falling rate of abalone after the heat stress compared with the control (P < 0.05). In conclusion, the optimal dietary EPA requirement of juvenile abalone was determined as 1.36% based on quadratic regression analysis against WGR. Moderate dietary EPA content (0.63% ∼ 1.07%) improved the immunity and heat resistance of abalone. Excessive dietary EPA content (1.72% ∼ 2.25%) decreased the growth, meanwhile, increasing the oxidative stress, inflammation and susceptibility of abalone to heat stress. • Effects of dietary EPA (0.03–2.25%) on the growth and health of abalone were studied. • Dietary EPA supplementation (0.24–2.25%) improved the growth of abalone. • Based on the WGR, the dietary EPA requirement of abalone was determined as 1.36%. • The 0.63–1.07% of dietary EPA improved the immunity and heat resistance of abalone. • The 2.25% of dietary EPA decreased the growth and health of abalone. [ABSTRACT FROM AUTHOR]

The sabellid polychaete Terebrasabella heterouncinata (Fitzhugh & Rouse 1999) has a unique life history in which larvae settle on the edge of gastropod shells and rely on shell deposition to create a tube with an opening to the exterior. This worm was accidentally imported to California, USA on abalone from South Africa in the 1980s and spread with abalone shipments to most culture facilities and some public aquaria throughout the state. Its ability to infest California's native gastropods has sparked concern regarding potential establishment in intertidal habitats adjacent to facilities that held sabellid-positive abalone. We examined the ability of T. heterouncinata to transmit between individual turban snails, Tegula funebralis. We found that transmission between T.funebralis did occur, but at a significantly slower rate than that between red abalone Haliotis rufescens. During 2002 to 2006 native gastropods (turban snails and limpets) were collected at most sabellid-exposed sites and no T. heterouncinata were detected; it thus appears that this species has not become established in California. Freshwater exposure was examined as a method to kill T. heterouncinala in shell fragments that may remain after abalone are removed from production or display units. Freshwater immersion for up to 8 hours but not 16 or 32 h resulted in survival of adults and/or larvae resident in brood chambers. In a similar study, motile T. heterouncinata larvae were found to survive up to 32 see of freshwater exposure, whereas none survived a 64-sec exposure. These data can be used by abalone culture and display facilities to establish reliable sanitization procedures to prevent T. heterouncinata transmission or reinfestation.

Abalone are broadcast spawners but, as this California Sea Grant research is showing, fertilization is more than just random collisions between gametes floating in the vast sea.

The objectives of the Diablo Canyon Archaeology project were to (1) refine the dating of archaeological sites CA-SLO-2 and CA-SLO-585; (2) identify the mammal, bird, and fish bones from these sites; (3) employ the resulting temporally controlled faunal matrix to improve understanding of California’s earliest coastal inhabitants and (4) address issues of nearshore ecology related to prehistoric human predation on sea otters and abalone as represented in the faunal record. The project was supposed to result in a published peer-reviewed paper and possible participation in a symposium on restoration ecology.

Abalone amyotrophia is a viral disease that causes mass mortality of juvenile Haliotis discus and H. madaka. Although the cause of this disease has yet to be identified, we had previously postulated a novel virus with partial genome sequence similarity to that of African swine fever virus is the causative agent and proposed abalone asfa-like virus (AbALV) as a provisional name. In this study, three species of juvenile abalone (H. gigantea, H. discus discus, and H. diversicolor) and four species of adult abalone (the above three species plus H. discus hannai) were experimentally infected, and their susceptibility to AbALV was investigated by recording mortality, quantitatively determining viral load by PCR, and conducting immunohistological studies. In the infection test using 7-month-old animals, H. gigantea, which was previously reported to be insusceptible to the disease, showed multiplication of the virus to the same extent as in H. discus discus, resulting in mass mortality. H. discus discus at 7 months old showed abnormal cell masses, notches in the edge of the shell and brown pigmentation inside of the shell, which are histopathological and external features of this disease, while H. gigantea did not show any of these characteristics despite suffering high mortality. Adult abalones had low mortality and viral replication in all species; however, all three species, except H. diversicolor, became carriers of the virus. In immunohistological observations, cells positive for viral antigens were detected predominantly in the gills of juvenile H. discus discus and H. gigantea, and mass mortality was observed in these species. In H. diversicolor, neither juvenile nor adult mortality from infection occurred, and the AbALV genome was not increased by experimental infection through cohabitation or injection. Our results suggest that H. gigantea, H. discus discus and H. discus hannai are susceptible to AbALV, while H. diversicolor is not. These results confirmed that AbALV is the etiological agent of abalone amyotrophia.

The New Zealand abalone industry relies mostly on the export of processed products to distant Asian markets, notably China. Over the past five years, live export of high quality abalone from New Zealand has proven successful. However, transport of live animals is associated with multiple stressors that affect survival and meat quality at the end of the transport phase. Better understanding of transport-derived stress is needed to improve transport conditions and recovery at destination to ensure high product quality and safety throughout the supply chain. To this end, we applied an untargeted GC–MS-based metabolomics approach to examine the changes in metabolite profiles of abalone after a 2-day transport event and subsequent water re-immersion for 2 days. The results revealed alterations of many metabolites in the haemolymph and muscle of post-transported abalone. Decreased concentrations of many amino acids suggest high energy demands for metabolism and stress responses of transported abalone, while increases of other amino acids may indicate active osmoregulation and/or protein degradation due to oxidative stress and apoptosis. The accumulation of citric acid cycle intermediates and anaerobic end-products are suggestive of hypoxia stress and a shift from aerobic to anaerobic metabolism (resulting from aerial exposure). Interestingly, some features in the metabolite profile of reimmersed abalone resembled those of pre-transported individuals, suggesting progressive recovery after reimmersion in water. Evidence of recovery was observed in the reduction of some stress biomarkers (e.g., lactic acid, succinic acid) following reimmersion. This study revealed insights into the metabolic responses to transport stress in abalone and highlights the importance of reimmersion practices in the supply chain of live animal exports.

The present study was conducted to investigate the roles of ascorbic acid (AA) in immune response, anti-oxidation and apoptosis in abalone (Haliotis discus hannai Ino). Seven semi-purified diets with graded levels of AA (0, 50, 100, 200, 500, 1000 and 5000 mg/kg) were fed to abalone (initial weight: 12.01 ± 0.001 g, initial shell length: 48.44 ± 0.069 mm) for 100 days. The survival, weight gain rate and daily increment in shell length were not affected by dietary AA. The AA content in the gill, muscle and digestive glands of abalone was significantly increased by dietary AA. In terms of immunity, dietary AA significantly improved the total hemocyte count, respiratory burst and phagocytic activity in hemolymph, and lysozyme activity in cell-free hemolymph (CFH). In the digestive gland, the TLR-MyD88-dependent and TLR-MyD88-independent signaling pathways were suppressed by dietary AA supplementation. The mRNA levels of β-defensin and arginase-I in the digestive gland were significantly increased by dietary AA. In the gill, only the TLR-MyD88-dependent signaling pathway was depressed by dietary AA to reduce inflammation in abalone. The level of mytimacin 6 in the gill was significantly upregulated by dietary AA. After Vibrio parahaemolyticus infection, the TLR signaling pathway in the digestive gland was suppressed by dietary AA, which reduced inflammation in the abalone. In terms of anti-oxidation, superoxide dismutase, glutathione peroxidase and catalase activities, as well as total anti-oxidative capacity and reduced glutathione content in CFH, were all significantly upregulated. The malondialdehyde content was significantly downregulated by dietary AA. The anti-oxidative capacity was improved by triggering the Keap1-Nrf2 pathway in abalone. In terms of apoptosis, dietary AA could enhance the anti-apoptosis ability via the JNK-Bcl-2/Bax signaling cascade in abalone. To conclude, dietary AA was involved in regulating immunity, anti-oxidation and apoptosis in abalone.

Arginine plays an important role in the regulation of the target of the rapamycin (TOR) signaling pathway, and Solute Carrier Family 38 Member 9 (SLC38A9) was identified to participate in the amino acid-dependent activation of TOR in humans. However, the regulations of arginine on the TOR signaling pathway in abalone are still unclear. In this study, slc38a9 of abalone was cloned, and the slc38a9 was knocked down and overexpressed to explore its function in the regulation of the TOR signaling pathway. The results showed that knockdown of slc38a9 decreased the expression of tor, ribosomal s6 protein kinase (s6k) and eukaryotic translation initiation factor 4e (eif4e) and inhibited the activation of the TOR signaling pathway by arginine. Overexpression of slc38a9 up-regulated the expression of TOR-related genes. In addition, hemocytes of abalone were treated with 0, 0.2, 0.5, 1, 2 and 4 mmol/L of arginine, and abalones were fed diets with 1.17%, 1.68% and 3.43% of arginine, respectively, for 120 days. Supplementation of arginine (0.5–4 mmol/L) increased the expressions of slc38a9, tor, s6k and eif4e in hemocytes, and abalone fed with 1.68% of dietary arginine showed higher mRNA levels of slc38a9, tor, s6k and eif4e and phosphorylation levels of TOR, S6 and 4E-BP. In conclusion, the TOR signaling pathway of abalone can be regulated by arginine, and SLC38A9 plays an essential role in this regulation.

Sea Grant research has led to the development of a cure for an abalone wasting disease that destroyed about $1.5-million worth of farmed abalone product at two California farms during the1997–98 El Niño. The antibiotic therapy is now being used to help in the restoration of endangered wild white abalone on the U.S. West Coast.

The red abalone, Haliotis rufescens Swainson 1822, supports the only recreational free-dive abalone fishery in the United States. I examined annual survivorship of three size classes ( 178 mm) of red abalone from five sites in northern California and one site in southern California using capture-mark-recapture data. Survival was variable spatially and among size classes. Survivorship values were incorporated into a size based projection matrix model. Elasticity values were found to be greatest for the sub-legal red abalone 150 mm to 178 mm (maximum shell length) indicating that changes in the vital rates of this size class are most important to population growth. Current methods to describe the age-at-length relationship of red abalone are insufficient because shell lengths exceed those predicted by growth models. I evaluated the utility of analyzing atomic bomb generated radioisotope 14C in shell to validate this relationship.

In this project, Michael Graham, a marine ecologist at Moss Landing Marine Laboratories, demonstrated the feasibility of vegetatively propagating red algae for the Monterey Abalone Company, a medium-sized abalone farm in Monterey Harbor that does not use synthetic feeds in its culturing operations. The main success of the project wasthe abilityto grow algae on 10-meter rope lines placed just outside Monterey Harbor.