Saccostrea Glomerata Research Articles

A metabolomic analysis on the toxicological effects of the universal solvent, dimethyl sulfoxide

Dimethyl sulfoxide (DMSO) is a solvent used to dissolve a variety of organic compounds. It is presumed to be non-toxic at concentrations below 10 % v/v, although several studies have demonstrated that low dose DMSO exposure can alter cellular biochemistry. This study evaluated the toxicity of DMSO at 0.0002 % v/v to the Sydney Rock oyster, Saccostrea glomerata, following 7d of exposure. Metabolites were chosen as the toxicity endpoints because they can be used as energy sources and counteract contaminant-induced stress. Relative to seawater controls, exposure to DMSO caused a 74 % significant change in metabolites in the female digestive gland, including decreases in most amino acids, carbohydrates, nicotinamides, and lipids. The female gonad showed a 43 % significant change in metabolites, with decreases in amino acids and carbohydrates, but increases in lipids. The male digestive gland showed a 29 % significant change in metabolites, with increases in lipids. The decline in metabolites in the female digestive glands but not in males may be due to their differential metabolic demands. Furthermore, pathway impact analysis revealed that DMSO exposure altered energy metabolism, disturbed osmotic balance, and induced oxidative stress in oysters. Because the effects of DMSO are not uniform across gender and tissue, use of DMSO as a solvent will confound metabolomic experimental results when comparisons among sexes and/or tissues are integral to the experimental design. There is a risk of incomplete dissolution of contaminants unless carrier solvents are used. Therefore, in practice, a water control along with a solvent control is recommended for any experimentation.

Ocean warming and Marine Heatwaves unequally impact juvenile introduced and native oysters with implications for their coexistence and future distribution

Climate change is causing ocean warming (OW) and increasing the frequency, intensity, and duration of extreme weather events, including Marine Heat Waves (MHWs). Both OW and MHWs pose a significant threat to marine ecosystems and marine organisms, including oysters, oyster reefs and farmed oysters. We investigated the survival and growth of juveniles of two commercial species of oyster, the Sydney rock oyster, Saccostrea glomerata, and the Pacific oyster, Crassostrea gigas, to elevated seawater temperatures reflecting a moderate and an extreme MHW in context with recent MHWs and beyond. The survival and size of Pacific oysters to moderate MHWs (22–32 °C; 14 days) was greater than that for Sydney rock oysters (24–32 °C; 15 days). While survival and growth of both species was significantly impacted by extreme MHWs (29–38 °C; 5–6 days), Sydney rock oysters were found to survive greater temperatures compared to the Pacific oyster. Overall, this study found that Pacific oyster juveniles were more tolerant of a moderate MHW, while Sydney rock oyster juveniles were more resilient to extreme MHWs. These differences in thermal tolerance may have consequences for aquaculture and coexistence of both species in their intertidal and latitudinal distributions along the south-eastern Australian coastline.

Determining the best practice for Sydney rock oyster, Saccostrea glomerata, reef restoration and enhanced ecological benefits

BackgroundShellfish reef restoration is relatively new in Australia, particularly to intertidal estuarine environments. In late 2019/early 2020 the first large-scale shellfish reef restoration project of the Sydney rock oyster, Saccostrea glomerata was undertaken in the Myall and Karuah Rivers, Port Stephens, on the mid north coast of New South Wales (NSW), Australia. The present study aimed to determine whether locally sourced clean conspecific oyster shells, and/or locally quarried rocks were better for natural recruitment of natural S. glomerata for large-scale oyster reef restoration, and subsequent recruitment of fishes and invertebrates. Over two years, recruitment of S. glomerata spat, and associated fishes and invertebrates were assessed on reefs made of: (1) rock, and (2) rock and shell.ResultsThe mean (± SE) density of oyster spat on rock reefs (Myall River: 1790 ± 48, Karuah River: 1928 ± 68) was significantly greater (Myall River: ANOVA Si: MS 2, 18 = 31080167, F = 96.05, P < 0.001, Karuah River: ANOVA Si x Ti: MS 18, 270 = 2965449, F = 5.99, P < 0.001) than on rock and shell reefs (Myall River: 840 ± 40, Karuah River: 1505 ± 75). Rock reefs had significantly greater densities (Myall River: ANOVA Si x Ti: MS 18, 270 = 15657, F = 2.71, P < 0.001, Karuah River: ANOVA Si x Ti: MS 18, 270 = 20322, F = 5.25, P < 0.001) of the most abundant invertebrate, Bembicium auratum (Myall River: 85 ± 9, Karuah River: 100 ± 8) than reefs of rock and shell (Myall River: 59 ± 8, Karuah River: 44 ± 5), but there was no significant difference in the diversity and relative abundance of the most abundant species of fish, Acanthopagrus australis.ConclusionsThis study demonstrates that using locally sourced rock is better for S. glomerata recruitment than shells. Although shell might have benefits that were not investigated in the present study, such as elicit greater social licence for oyster reef restoration projects, but as shown here, it may not be beneficial from an ecological perspective. With the global expansion of the range of different native species of reef oysters for restoration, the appropriate material used for reef bases needs to be chosen for a specific species and purpose.

Meta-analyses reveal climate change impacts on an ecologically and economically significant oyster in Australia

Meta-analyses reveal climate change impacts on an ecologically and economically significant oyster in Australia

Exploring the co-exposure effects of environmentally relevant microplastics and an estrogenic mixture on the metabolome of the Sydney rock oyster

In aquatic environments the concurrent exposure of molluscs to microplastics (MPs) and estrogens is common, as these pollutants are frequently released by wastewater treatment plants into estuaries. Therefore, this study aimed to evaluate the independent and co-exposure impacts of polyethylene microplastics (PE-MPs) and estrogenic endocrine-disrupting chemicals (EEDCs) at environmentally relevant concentrations on polar metabolites and morphological parameters of the Sydney rock oyster. A seven-day acute exposure revealed no discernible differences in morphology; however, significant variations in polar metabolites were observed across oyster tissues. The altered metabolites were mostly amino acids, carbohydrates and intermediates of the Kreb's cycle. The perturbation of metabolites were tissue and sex-specific. All treatments generally showed an increase of metabolites relative to controls – a possible stimulatory and/or a potential hormetic response. The presence of MPs impeded the exposure of adsorbed and free EEDCs potentially due to the selective feeding behaviour of oysters to microplastics, favouring algae over similar-sized PE-MPs, and the formation of an eco/bio-corona involving faeces, pseudo-faeces, natural organic matter, and algae.

The development of multiplex PCR assays for the rapid identification of multiple Saccostrea species, and their practical applications in restoration and aquaculture

BackgroundThe ecology and biology of oysters (Ostreidae) across the tropics is poorly understood. Morphological plasticity and shared characteristics among oysters have resulted in the misidentification of species, creating challenges for understanding basic species-specific biological information that is required for restoration and aquaculture. Genetic barcoding has proven essential for accurate species identification and understanding species geographic ranges. To reduce the costs of molecular species identification we developed multiplex assays using the cytochrome c oxidase subunit I (COI or cox1) barcoding gene for the rapid identification of five species of oysters within the genus Saccostrea that are commonly found in Queensland, Australia: Saccostrea glomerata, Saccostrea lineage B, Saccostrea lineage F, Saccostrea lineage G, and Saccostrea spathulata (lineage J).ResultsMultiplex assays were successful in species-specific amplification of targeted species. The practical application of these primers was tested on wild spat collected from a pilot restoration project in Moreton Bay, Queensland, with identified species (S. glomerata, lineage B and lineage G) validated by Sanger sequencing. DNA sampling by extraction of oyster pallial fluid was also tested on adult oysters collected from the Noosa estuary in Queensland to assess whether oysters were able to be identified non-destructively. DNA concentrations as low as 1 ng/ μL still amplified in most cases, allowing for identification, and mortality at 6 weeks post pallial fluid collection was low (3 out of 104 sampled oysters).ConclusionThese multiplex assays will be essential tools for species identification in future studies, and we successfully demonstrate their practical application in both restoration and aquaculture contexts in Queensland. The multiplex assays developed in this study outline easily replicable methods for the development of additional species-specific primer sets for the rapid identification of other species of Saccostrea found across the Indo-Pacific, which will be instrumental in unravelling the taxonomic ambiguities within this genus in tropical regions.

Recruitment of a threatened foundation oyster species varies with large and small spatial scales.

Understanding how habitat attributes (e.g., patch area and sizes, connectivity) control recruitment and how this is modified by processes operating at larger spatial scales is fundamental to understanding population sustainability and developing successful long-term restoration strategies for marine foundation species-including for globally threatened reef-forming oysters. In two experiments, we assessed the recruitment and energy reserves of oyster recruits onto remnant reefs of the oyster Saccostrea glomerata in estuaries spanning 550 km of coastline in southeastern Australia. In the first experiment, we determined whether recruitment of oysters to settlement plates in three estuaries was correlated with reef attributes within patches (distances to patch edges and surface elevation), whole-patch attributes (shape and size of patches), and landscape attributes (connectivity). We also determined whether environmental factors (e.g., sedimentation and water temperature) explained the differences among recruitment plates. We also tested whether differences in energy reserves of recruits could explain the differences between two of the estuaries (one high- and one low-sedimentation estuary). In the second experiment, across six estuaries (three with nominally high and three with nominally low sedimentation rates), we tested the hypothesis that, at the estuary scale, recruitment and survival were negatively correlated to sedimentation. Overall, total oyster recruitment varied mostly at the scale of estuaries rather than with reef attributes and was negatively correlated with sedimentation. Percentage recruit survival was, however, similar among estuaries, although energy reserves and condition of recruits were lower at a high- compared to a low-sediment estuary. Within each estuary, total oyster recruitment increased with patch area and decreased with increasing tidal height. Our results showed that differences among estuaries have the largest influence on oyster recruitment and recruit health and this may be explained by environmental processes operating at the same scale. While survival was high across all estuaries, growth and reproduction of oysters on remnant reefs may be affected by sublethal effects on the health of recruits in high-sediment estuaries. Thus, restoration programs should consider lethal and sublethal effects of whole-estuary environmental processes when selecting sites and include environmental mitigation actions to maximize recruitment success.

Molecular identification of intertidal rock oyster species in north-eastern Australia reveals new candidates for aquaculture

Oyster aquaculture in Australia is currently centred on two species, Saccostrea glomerata (Gould, 1850) and Magallana gigas (Thunberg, 1793) which are both susceptible to disease. Disease outbreaks have caused significant losses to the industry and there is currently an appetite for diversification to mitigate risk. Development of other, native oyster species for aquaculture is limited by a poor understanding of their biodiversity and distribution, which is primarily due to the difficulty in distinguishing species based on morphology alone. In this study we sampled intertidal rock oysters from 19 localities in north-eastern Australia and performed phylogenetic analyses based on partial COI and 16S mitochondrial markers. A total of 14 distinct oyster lineages (most likely representing distinct species) were identified from the 357 specimens collected and sequenced. In total, we report the presence of 8 Saccostrea lineages, 4 Ostreinae lineages, one Magallana lineage (Magallana bilineata (Röding, 1798), a recent introduction), and one Talonostrea lineage (likely undescribed). A number of these lineages have broad distributions and attain large sizes, and several are currently cultured in other parts of the world. Although morphological identification is challenging we argue that the large size of the tropical black-lip oyster, Saccostrea lineage J, enables it to be definitively identified as Saccostrea spathulata (Lamarck 1819), thus providing taxonomic certainty for this commercially important species. The identification of these oyster lineages and their distributions is a fundamental step towards development of viable alternatives for oyster aquaculture in the region.

Habitat‐setting affects biodiversity while predation determines oyster survival on experimental oyster reefs

Foundation species are being restored into inherently variable landscapes with multiple, interspersed habitats. However, understanding of the influence of different neighbouring habitats on community assembly and the survival of restored species is limited, despite their significant potential to affect restoration outcomes. We tested how habitat‐setting (being next to seagrass, seagrass and mangroves, or unvegetated sediments) and predation (by meso‐ and/or large predators) influenced macroinvertebrate community assembly and the survival of juvenile Sydney rock oysters (Saccostrea glomerata) on experimental oyster reef units in the Port Hacking estuary, New South Wales, Australia. Each habitat‐setting produced a distinct macroinvertebrate community on experimental reefs, whereas predation had limited effects on community structure. Juvenile oysters were instead highly predated everywhere, and oyster predation was dominated by the large, transient fish Acanthropagrus australis. Our findings allow practitioners to predict and tailor the communities which establish on restored oyster reefs by strategically placing them next to different habitats. If sites have a high predation risk but require seeding for reefs to establish, then caging or complex substrates must be used to increase seeded oyster survival.

Semi-purified Antimicrobial Proteins from Oyster Hemolymph Inhibit Pneumococcal Infection

Pneumococcal infections caused by Streptococcus pneumoniae are a leading cause of morbidity and mortality globally, particularly among children. The ability of S. pneumoniae to form enduring biofilms makes treatment inherently difficult, and options are further limited by emerging antibiotic resistance. The discovery of new antibiotics, particularly those with antibiofilm activity, is therefore increasingly important. Antimicrobial proteins and peptides (AMPs) from marine invertebrates are recognised as promising pharmacological leads. This study determined the in vitro antibacterial activity of hemolymph and unique protein fractions from an Australian oyster (Saccostrea glomerata) against multi-drug-resistant S. pneumoniae. We developed a successful method for hemolymph extraction and separation into 16 fractions by preparative HPLC. The strongest activity was observed in fraction 7: at 42 µg/mL protein, this fraction was bactericidal to S. pneumoniae and inhibited biofilm formation. Proteomic analysis showed that fraction 7 contained relatively high abundance of carbonic anhydrase, cofilin, cystatin B–like, and gelsolin-like proteins, while surrounding fractions, which showed lower or no antibacterial activity, contained these proteins in lower abundance or not at all. This work supports traditional medicinal uses of oysters and contributes to further research and development of novel hemolymph/AMP-based treatments for pneumococcal infections.

The archaeology of 19th century oyster consumption in Melbourne

ABSTRACTThis paper presents comparative research on marine shell from four 19th century historical archaeological sites in Melbourne. The shell derives predominantly from Mud Oyster (Ostrea angasi) and Sydney Rock Oyster (Saccostrea glomerata) commercially harvested from natural reefs along the south‐east Australian coastline. The research collects quantitative data that informs on the 19th century oyster industry and investigates inter‐site shell variability and its implications for processing, consumption and discard. Dredging of subtidal reefs provides an explanation for the numerical dominance of oyster, the presence of subfossil cultch (Anadara) and the wide range of minor shellfish. Mud oyster and Sydney rock oyster comparisons in valve size, sided counts and preservation record significant differences within and between sites due to the origins, depositional conditions and the processing of the shell. These data form the basis of two models. The first predicts the archaeological representation of reef dredging and ranks shellfish according to categories, from live oysters to dead shell sampled from the reef substrate. Based on oyster shell anatomy and the separate uses of the right (lid) and left (dish) valves, the second model considers how oyster processing and consumption is characterised archaeologically in differential valve counts and pairing rates.

Resilience against the impacts of climate change in an ecologically and economically significant native oyster

Climate change is acidifying and warming our oceans, at an unprecedented rate posing a challenge for marine invertebrates vital across the globe for ecological services and food security. Here we show it is possible for resilience to climate change in an ecologically and economically significant oyster without detrimental effects to the energy budget. We exposed 24 pair-mated genetically distinct families of the Sydney rock oyster, Saccostrea glomerata to ocean acidification and warming for 4w and measured their resilience. Resilience was identified as the capacity to defend their acid-base balance without a loss of energy available for Scope for Growth (SFG). Of the 24 families, 13 were better able to defend their acid-base balance while eight had no loss of energy availability with a positive SFG. This study has found oyster families with reslience against climate change without a loss of SFG, is an essential mitigation strategy, in a critical mollusc.

A novel role for Teneurin C-terminal Associated Peptide (TCAP) in the regulation of cardiac activity in the Sydney rock oyster, Saccostrea glomerata.

Teneurin C-terminal associated peptide (TCAP) is an ancient bioactive peptide that is highly conserved in metazoans. TCAP administration reduces cellular and behavioural stress in vertebrate and urochordate models, yet despite numerous studies in higher animals, there is limited knowledge of its role in invertebrates. In particular, there are no studies on TCAP's effects on the heart of any metazoan, which is a critical organ in the stress response. We used the Sydney rock oyster (SRO) as an invertebrate model to investigate a potential role for sroTCAP in regulating cardiac activity, including during stress. sroTCAP is localized to the neural innervation network of the SRO heart, and suggested binding with various heart proteins related to metabolism and stress, including SOD, GAPDH and metabotropic glutamate receptor. Intramuscular injection of sroTCAP (10 pmol) significantly altered the expression of heart genes that are known to regulate remodelling processes under different conditions, and modulated several gene families responsible for stress mitigation. sroTCAP (1 and 10 pmol) was shown to cause transient bradycardia (heart rate was reduced by up to 63% and for up to 40min post-administration), indicative of an unstressed state. In summary, this study has established a role for a TCAP in the regulation of cardiac activity through modulation of physiological and molecular components associated with energy conservation, stress and adaptation. This represents a novel function for TCAP and may have implications for higher-order metazoans.

Transgenerational transfer of the microbiome is altered by ocean acidification in oyster larvae

Ocean acidification will affect marine molluscs, however, transgenerational plasticity (TGP) can ameliorate some effects. Marine molluscs acquire members of their microbiome via the egg, yet we know little about how the microbiome can be influenced by transgenerational exposure to ocean acidification. We exposed adult Sydney Rock oysters (Saccostrea glomerata) from four genotypes to elevated and ambient PCO2 for nine weeks. Larvae were then raised in the same ambient and elevated PCO2 conditions. The relative abundance of bacteria in eggs and larvae were characterised using 16S RNA amplicon sequencing. Parental exposure to elevated PCO2 significantly altered the bacterial community composition of both eggs and larvae, but this was dependent on genotype. Parental exposure to elevated PCO2 caused five core Rhodobacteraceae ASVs to increase in relative abundance, and three Rhodobacteraceae ASVs to decrease in relative abundance. These findings show transfer of maternal microbiomes to larvae is altered by exposure to ocean acidification and this may play a role in TGP.

Exposure to multiple elements reduces the health of Saccostrea glomerata: An assessment of the Richmond River estuary, NSW, Australia.

This study investigated relationships between Sydney Rock Oyster (SRO) health and element concentrations in sediments and oysters from the Richmond River estuary. Six sites were sampled between November 2019 and May 2020. Multivariate permutational analysis of variance was used to compare oyster health parameters and element concentrations between sites, wet and dry conditions, and in oyster and sediment samples. Statistical analysis revealed significant spatial differences in oyster mortality, condition index, and size. Metal concentrations in oyster flesh significantly differed from metals in sediments. Most metals in sediments were below guideline values, except for Ni at some sites. Mortality, condition index, and weight correlated negatively with individual elements in oyster flesh (P, Zn, Mg, Al, Ni). BEST statistical models included various combinations of metals in sediment and flesh. This study highlights that spatial differences in SRO health tend to be related to site-specific metal compositions in sediment and oysters.

Heavy metals in cultured oysters (Saccostrea glomerata) and clams (Meretrix lyrata) from the northern coastal area of Vietnam

Oysters and clams are abundant and popularly consumed seafood in Viet Nam. These bivalves were proved to be suitable bioindicators to assess the heavy metal accumulation in the aquatic environment. The study is to investigate heavy metals such as As, Cd, Hg and Pb in the cultured oysters Saccostrea glomerata and clams Meretrix lyrata collected in VanDon - Quang Ninh, and CatBa - Hai Phong. The results showed that the metal heavy concentrations in the oysters Saccostrea glomerata and clams Meretrix lyrata presented in the order of As > Cd>Pb>Hg. The most polluted concentration with As among four heavy metals studied in six sampling sites was 2.81±1.07 and 1.6±0.62mg/kg wet weight for clams and oysters, respectively. Investigated heavy metals in cultured oysters and clams indicated potential risks for human health in future by assessment of the heavy metals.

Observation of juvenile Eastern Blue Groper (Achoerodus viridis) on remnant oyster reefs in New South Wales, Australia.

Observation of juvenile Eastern Blue Groper (Achoerodus viridis) on remnant oyster reefs in New South Wales, Australia.

An ecological assessment of Australia's first community oyster gardens

SummaryOyster gardening is a community‐driven activity where oysters are grown in cages hanging off docks or other coastal infrastructure. Besides the provision of adult oysters for restoration programmes, oyster gardening may also support other ecosystem services such as providing habitat for fishes and invertebrates as well as encouraging community involvement and citizen science. Australia's first oyster gardening programme was undertaken in a canal estate on Bribie Island in Moreton Bay, Queensland between October 2016 and November 2017. Oyster gardens consisting of plastic mesh cages were deployed with either three species of bivalves (polyculture), or exclusively Sydney Rock Oysters (monoculture) to investigate whether the habitat value differed between the two garden types. After one year of growth, polyculture cages supported higher abundances and species richness of both invertebrates and fish compared to the monoculture gardens. Our study showed that oyster gardening can provide habitat for a range of invertebrate and fish species in the highly modified coastal environment of a canal estate. Further studies are needed to discern whether these oyster gardens would also support larger and mobile fauna, such as species with commercial and recreational importance.

Microplastic in oysters: A review of global trends and comparison to southern Australia

Microplastics have been documented in a plethora of marine environments and organisms. These small plastics threaten ecosystem health, with implications for seafood species’ health. Oysters are an important cultural and economic aquaculture species globally. Due to their filter feeding mechanisms, they can act as an indicator species and proxy for environmental contamination. This makes them an ideal organism for investigating microplastic pollution. Here, we first systematically reviewed the global literature investigating microplastic in oysters. Globally, 94.4% of all oysters had microplastics, with an average of 1.41 ± 0.33 per gram of soft tissue wet weight (gww). The review showed that wild-caught oysters contained more than double the amount of microplastic than aquaculture raised specimens, likely reflecting the clean and productive waters in which oyster aquaculture systems are commonly located. Second, we quantified microplastic presence and polymer type in commercially farmed oysters (Crassostrea gigas and Saccostrea glomerata) across a broad spatial scale, covering eight sites in southern Australia. Microplastics were present in 49.4% of all sampled oysters, with specimens from all locations containing microplastics. On average, whole oysters contained 0.83 ± 0.08 microplastics per individual or 0.09 ± 0.01 microplastics gww. Using Fourier-Transform Infrared Spectroscopy, we identified that 62% of the verified microplastics were vexar plastic netting, a low-density polyethylene commonly used in aquaculture production. Understanding the abundance and source of microplastic in these key seafood species is essential to determine if oysters are vulnerable to these contaminants and pose a risk to the oyster aquaculture industry as an important food resource.

Teneurin and TCAP Phylogeny and Physiology: Molecular Analysis, Immune Activity, and Transcriptomic Analysis of the Stress Response in the Sydney Rock Oyster (Saccostrea glomerata) Hemocytes.

Teneurin C-terminal associated peptide (TCAP) is an ancient bioactive peptide that is highly conserved in metazoans. TCAP administration reduces cellular and behavioral stress in vertebrate and urochordate models. There is little information for invertebrates regarding the existence or function of a TCAP. This study used the Sydney rock oyster (SRO) as a molluscan model to characterize an invertebrate TCAP, from molecular gene analysis to its physiological effects associated with hemocyte phagocytosis. We report a single teneurin gene (and 4 teneurin splice variants), which encodes a precursor with TCAP that shares a vertebrate-like motif, and is similar to that of other molluscan classes (gastropod, cephalopod), arthropods and echinoderms. TCAP was identified in all SRO tissues using western blotting at 1-2 different molecular weights (~22 kDa and ~37kDa), supporting precursor cleavage variation. In SRO hemolymph, TCAP was spatially localized to the cytosol of hemocytes, and with particularly high density immunoreactivity in granules. Based on ‘pull-down’ assays, the SRO TCAP binds to GAPDH, suggesting that TCAP may protect cells from apoptosis under oxidative stress. Compared to sham injection, the intramuscular administration of TCAP (5 pmol) into oysters modulated their immune system by significantly reducing hemocyte phagocytosis under stress conditions (low salinity and high temperature). TCAP administration also significantly reduced hemocyte reactive oxygen species production at ambient conditions and after 48 h stress, compared to sham injection. Transcriptomic hemocyte analysis of stressed oysters administered with TCAP demonstrated significant changes in expression of genes associated with key metabolic, protective and immune functions. In summary, this study established a role for TCAP in oysters through modulation of physiological and molecular functions associated with energy conservation, stress and cellular defense.