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.

Human-nature relationships: An introduction to social-ecological practice theory for human-wildlife interactions.

Conservation science requires a balance of social and ecological perspectives to understand human-wildlife interactions. We look for an integrative social-ecological framework that emphasizes equal representation across social and ecological conservation sciences. In this perspective, we suggest "social-ecological practice theory", an integration of general ecological theory and anthropology's practice theory, for a conservation-minded social-ecological framework to better theorize human-nature relationships. Our approach deliberately pulls from subdisciplines of anthropology, specifically a body of social theory founded by anthropology and social science called practice theory. We then illustrate how to apply social-ecological practice theory to our case study in the Makgadikgadi region of Botswana. We highlight how the practices of people, lions, and cattle-in combination with environmental and structural features-provide the needed context to deepen the understanding of human-wildlife conflict in the region. Social-ecological practice theory highlights the complexity that exists on the landscape, and may more effectively result in conservation strategies for human-wildlife coexistence.

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 40 min 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.

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.

Microbiomes of an oyster are shaped by metabolism and environment.

Microbiomes can both influence and be influenced by metabolism, but this relationship remains unexplored for invertebrates. We examined the relationship between microbiome and metabolism in response to climate change using oysters as a model marine invertebrate. Oysters form economies and ecosystems across the globe, yet are vulnerable to climate change. Nine genetic lineages of the oyster Saccostrea glomerata were exposed to ambient and elevated temperature and PCO2 treatments. The metabolic rate (MR) and metabolic by-products of extracellular pH and CO2 were measured. The oyster-associated bacterial community in haemolymph was characterised using 16 s rRNA gene sequencing. We found a significant negative relationship between MR and bacterial richness. Bacterial community composition was also significantly influenced by MR, extracellular CO2 and extracellular pH. The effects of extracellular CO2 depended on genotype, and the effects of extracellular pH depended on CO2 and temperature treatments. Changes in MR aligned with a shift in the relative abundance of 152 Amplicon Sequencing Variants (ASVs), with 113 negatively correlated with MR. Some spirochaete ASVs showed positive relationships with MR. We have identified a clear relationship between host metabolism and the microbiome in oysters. Altering this relationship will likely have consequences for the 12 billion USD oyster economy.

Genomic Prediction for Whole Weight, Body Shape, Meat Yield, and Color Traits in the Portuguese Oyster Crassostrea angulata.

Genetic improvement for quality traits, especially color and meat yield, has been limited in aquaculture because the assessment of these traits requires that the animals be slaughtered first. Genotyping technologies do, however, provide an opportunity to improve the selection efficiency for these traits. The main purpose of this study is to assess the potential for using genomic information to improve meat yield (soft tissue weight and condition index), body shape (cup and fan ratios), color (shell and mantle), and whole weight traits at harvest in the Portuguese oyster, Crassostrea angulata. The study consisted of 647 oysters: 188 oysters from 57 full-sib families from the first generation and 459 oysters from 33 full-sib families from the second generation. The number per family ranged from two to eight oysters for the first and 12-15 oysters for the second generation. After quality control, a set of 13,048 markers were analyzed to estimate the genetic parameters (heritability and genetic correlation) and predictive accuracy of the genomic selection for these traits. The multi-locus mixed model analysis indicated high estimates of heritability for meat yield traits: 0.43 for soft tissue weight and 0.77 for condition index. The estimated genomic heritabilities were 0.45 for whole weight, 0.24 for cup ratio, and 0.33 for fan ratio and ranged from 0.14 to 0.54 for color traits. The genetic correlations among whole weight, meat yield, and body shape traits were favorably positive, suggesting that the selection for whole weight would have beneficial effects on meat yield and body shape traits. Of paramount importance is the fact that the genomic prediction showed moderate to high accuracy for the traits studied (0.38-0.92). Therefore, there are good prospects to improve whole weight, meat yield, body shape, and color traits using genomic information. A multi-trait selection program using the genomic information can boost the genetic gain and minimize inbreeding in the long-term for this population.

Microbiome response differs among selected lines of Sydney rock oysters to ocean warming and acidification.

Oyster microbiomes are integral to healthy function and can be altered by climate change conditions. Genetic variation among oysters is known to influence the response of oysters to climate change and may ameliorate any adverse effects on oyster microbiome; however, this remains unstudied. Nine full-sibling selected breeding lines of the Sydney rock oyster (Saccostrea glomerata) were exposed to predicted warming (ambient = 24°C, elevated = 28°C) and ocean acidification (ambient pCO2 = 400, elevated pCO2 = 1000 µatm) for 4 weeks. The haemolymph bacterial microbiome was characterized using 16S rRNA (V3-V4) gene sequencing and varied among oyster lines in the control (ambient pCO2, 24°C) treatment. Microbiomes were also altered by climate change dependent on oyster lines. Bacterial α-diversity increased in response to elevated pCO2 in two selected lines, while bacterial ß-diversity was significantly altered by combinations of elevated pCO2 and temperature in four selected lines. Climate change treatments caused shifts in the abundance of multiple amplicon sequence variants driving change in the microbiome of some selected lines. We show that oyster genetic background may influence the Sydney rock oyster haemolymph microbiome under climate change and that future assisted evolution breeding programs to enhance resilience should consider the oyster microbiome.

Prediction Accuracies of Genomic Selection for Nine Commercially Important Traits in the Portuguese Oyster (Crassostrea angulata) Using DArT-Seq Technology.

Genomic selection has been widely used in terrestrial animals but has had limited application in aquaculture due to relatively high genotyping costs. Genomic information has an important role in improving the prediction accuracy of breeding values, especially for traits that are difficult or expensive to measure. The purposes of this study were to (i) further evaluate the use of genomic information to improve prediction accuracies of breeding values from, (ii) compare different prediction methods (BayesA, BayesCπ and GBLUP) on prediction accuracies in our field data, and (iii) investigate the effects of different SNP marker densities on prediction accuracies of traits in the Portuguese oyster (Crassostrea angulata). The traits studied are all of economic importance and included morphometric traits (shell length, shell width, shell depth, shell weight), edibility traits (tenderness, taste, moisture content), and disease traits (Polydora sp. and Marteilioides chungmuensis). A total of 18,849 single nucleotide polymorphisms were obtained from genotyping by sequencing and used to estimate genetic parameters (heritability and genetic correlation) and the prediction accuracy of genomic selection for these traits. Multi-locus mixed model analysis indicated high estimates of heritability for edibility traits; 0.44 for moisture content, 0.59 for taste, and 0.72 for tenderness. The morphometric traits, shell length, shell width, shell depth and shell weight had estimated genomic heritabilities ranging from 0.28 to 0.55. The genomic heritabilities were relatively low for the disease related traits: Polydora sp. prevalence (0.11) and M. chungmuensis (0.10). Genomic correlations between whole weight and other morphometric traits were from moderate to high and positive (0.58-0.90). However, unfavourably positive genomic correlations were observed between whole weight and the disease traits (0.35-0.37). The genomic best linear unbiased prediction method (GBLUP) showed slightly higher accuracy for the traits studied (0.240-0.794) compared with both BayesA and BayesCπ methods but these differences were not significant. In addition, there is a large potential for using low-density SNP markers for genomic selection in this population at a number of 3000 SNPs. Therefore, there is the prospect to improve morphometric, edibility and disease related traits using genomic information in this species.

Climate change alters the haemolymph microbiome of oysters.

The wellbeing of marine organisms is connected to their microbiome. Oysters are a vital food source and provide ecological services, yet little is known about how climate change such as ocean acidification and warming will affect their microbiome. We exposed the Sydney rock oyster, Saccostrea glomerata, to orthogonal combinations of temperature (24, 28 °C) and pCO2 (400 and 1000 µatm) for eight weeks and used amplicon sequencing of the 16S rRNA (V3-V4) gene to characterise the bacterial community in haemolymph. Overall, elevated pCO2 and temperature interacted to alter the microbiome of oysters, with a clear partitioning of treatments in CAP ordinations. Elevated pCO2 was the strongest driver of species diversity and richness and elevated temperature also increased species richness. Climate change, both ocean acidification and warming, will alter the microbiome of S. glomerata which may increase the susceptibility of oysters to disease.

Heatwaves alter survival of the Sydney rock oyster, Saccostrea glomerata.

Heatwaves are an increasing threat to organisms across the globe. Marine and atmospheric heatwaves are predicted to impact sessile intertidal marine organisms, especially when exposed at low tide and unable to seek refuge. The study aimed to determine whether a simulated atmospheric heatwave will alter the survival of selectively bred families of Sydney rock oysters (Saccostrea glomerata), and whether survival is dependent on morphological and physiological traits. The survival of S. glomerata families to a simulated atmospheric heatwave varied from 25 to 60% and was not correlated with morphology or physiology. Survival may depend on the presence of genotypes that translate into molecular defenses such as heat-shock proteins and inhibitor of apoptosis proteins that provide oysters with resilience. Understanding the responses among families of oysters to heatwaves is critical if we are to restore the ecological services of oyster reefs and sustain oyster aquaculture.

Regional and oyster microenvironmental scale heterogeneity in the Pacific oyster bacterial community.

Different organs of a host represent distinct microenvironments resulting in the establishment of multiple discrete bacterial communities within a host. These discrete bacterial communities can also vary according to geographical location. For the Pacific oyster, Crassostrea gigas, the factors governing bacterial diversity and abundance of different oyster microenvironments are poorly understood. In this study, the factors shaping bacterial abundance, diversity and composition associated with the C. gigas mantle, gill, adductor muscle and digestive gland were characterised using 16S (V3-V4) rRNA amplicon sequencing across six discrete estuaries. Both location and tissue-type, with tissue-type being the stronger determinant, were factors driving bacterial community composition. Bacterial communities from wave-dominated estuaries had similar compositions and higher bacterial abundance despite being geographically distant from one another, possibly indicating that functional estuarine morphology characteristics are a factor shaping the oyster bacterial community. Despite the bacterial community heterogeneity, examinations of the core bacterial community identified Spirochaetaceae bacteria as conserved across all sites and samples. Whereas members of the Vulcaniibacterium, Spirochaetaceae and Margulisbacteria, and Polynucleobacter were regionally conserved members of the digestive gland, gill and mantle bacterial communities, respectively. This indicates that baseline bacterial community profiles for specific locations are necessary when investigating bacterial communities in oyster health.

Selectively bred oysters can alter their biomineralization pathways, promoting resilience to environmental acidification.

Commercial shellfish aquaculture is vulnerable to the impacts of ocean acidification driven by increasing carbon dioxide (CO2 ) absorption by the ocean as well as to coastal acidification driven by land run off and rising sea level. These drivers of environmental acidification have deleterious effects on biomineralization. We investigated shell biomineralization of selectively bred and wild-type families of the Sydney rock oyster Saccostrea glomerata in a study of oysters being farmed in estuaries at aquaculture leases differing in environmental acidification. The contrasting estuarine pH regimes enabled us to determine the mechanisms of shell growth and the vulnerability of this species to contemporary environmental acidification. Determination of the source of carbon, the mechanism of carbon uptake and use of carbon in biomineral formation are key to understanding the vulnerability of shellfish aquaculture to contemporary and future environmental acidification. We, therefore, characterized the crystallography and carbon uptake in the shells of S. glomerata, resident in habitats subjected to coastal acidification, using high-resolution electron backscatter diffraction and carbon isotope analyses (as δ13 C). We show that oyster families selectively bred for fast growth and families selected for disease resistance can alter their mechanisms of calcite crystal biomineralization, promoting resilience to acidification. The responses of S. glomerata to acidification in their estuarine habitat provide key insights into mechanisms of mollusc shell growth under future climate change conditions. Importantly, we show that selective breeding in oysters is likely to be an important global mitigation strategy for sustainable shellfish aquaculture to withstand future climate-driven change to habitat acidification.

Variability in the Composition of Pacific Oyster Microbiomes Across Oyster Families Exhibiting Different Levels of Susceptibility to OsHV-1 µvar Disease.

Oyster diseases are a major impediment to the profitability and growth of the oyster aquaculture industry. In recent years, geographically widespread outbreaks of disease caused by ostreid herpesvirus-1 microvariant (OsHV-1 µvar) have led to mass mortalities among Crassostrea gigas, the Pacific Oyster. Attempts to minimize the impact of this disease have been largely focused on breeding programs, and although these have shown some success in producing oyster families with reduced mortality, the mechanism(s) behind this protection is poorly understood. One possible factor is modification of the C. gigas microbiome. To explore how breeding for resistance to OsHV-1 µvar affects the oyster microbiome, we used 16S rRNA amplicon sequencing to characterize the bacterial communities associated with 35 C. gigas families, incorporating oysters with different levels of susceptibility to OsHV-1 µvar disease. The microbiomes of disease-susceptible families were significantly different to the microbiomes of disease-resistant families. OTUs assigned to the Photobacterium, Vibrio, Aliivibrio, Streptococcus, and Roseovarius genera were associated with low disease resistance. In partial support of this finding, qPCR identified a statistically significant increase of Vibrio-specific 16S rRNA gene copies in the low disease resistance families, possibly indicative of a reduced host immune response to these pathogens. In addition to these results, examination of the core microbiome revealed that each family possessed a small core community, with OTUs assigned to the Winogradskyella genus and the Bradyrhizobiaceae family consistent members across most disease-resistant families. This study examines patterns in the microbiome of oyster families exhibiting differing levels of OsHV-1 µvar disease resistance and reveals some key bacterial taxa that may provide a protective or detrimental role in OsHV-1 µvar disease outbreaks.

Coastal acidification impacts on shell mineral structure of bivalve mollusks.

Ocean acidification is occurring globally through increasing CO 2 absorption into the oceans creating particular concern for calcifying species. In addition to ocean acidification, near shore marine habitats are exposed to the deleterious effects of runoff from acid sulfate soils which also decreases environmental pH. This coastal acidification is being exacerbated by climate change-driven sea-level rise and catchment-driven flooding. In response to reduction in habitat pH by ocean and coastal acidification, mollusks are predicted to produce thinner shells of lower structural integrity and reduced mechanical properties threatening mollusk aquaculture. Here, we present the first study to examine oyster biomineralization under acid sulfate soil acidification in a region where growth of commercial bivalve species has declined in recent decades. Examination of the crystallography of the shells of the Sydney rock oyster, Saccostrea glomerata, by electron back scatter diffraction analyses revealed that the signal of environmental acidification is evident in the structure of the biomineral. Saccostrea glomerata, shows phenotypic plasticity, as evident in the disruption of crystallographic control over biomineralization in populations living in coastal acidification sites. Our results indicate that reduced sizes of these oysters for commercial sale may be due to the limited capacity of oysters to biomineralize under acidification conditions. As the impact of this catchment source acidification will continue to be exacerbated by climate change with likely effects on coastal aquaculture in many places across the globe, management strategies will be required to maintain the sustainable culture of these key resources.

Ocean acidification but not warming alters sex determination in the Sydney rock oyster, Saccostrea glomerata.

Whether sex determination of marine organisms can be altered by ocean acidification and warming during this century remains a significant, unanswered question. Here, we show that exposure of the protandric hermaphrodite oyster, Saccostrea glomerata to ocean acidification, but not warming, alters sex determination resulting in changes in sex ratios. After just one reproductive cycle there were 16% more females than males. The rate of gametogenesis, gonad area, fecundity, shell length, extracellular pH and survival decreased in response to ocean acidification. Warming as a sole stressor slightly increased the rate of gametogenesis, gonad area and fecundity, but this increase was masked by the impact of ocean acidification at a level predicted for this century. Alterations to sex determination, sex ratios and reproductive capacity will have flow on effects to reduce larval supply and population size of oysters and potentially other marine organisms.

First observations of perfluorooctane sulfonate occurrence and depuration from Sydney Rock Oysters, Saccostrea glomerata, in Port Stephens NSW Australia.

Following the discovery of potential chronic perfluoroalkyl substances (PFAS) contamination of Tilligerry Creek, Port Stephens (New South Wales Australia), sampling was undertaken to confirm the presence, extent and levels of contamination in commercial oyster crops of Sydney Rock Oyster (Saccostrea glomerata) and Pacific Oyster (Crassostrea gigas) grown within the estuary. Among a range of PFAS tested, only perfluorooctane sulfonate (PFOS) was detected. Concentrations of PFOS in oyster tissues for S. glomerata ranged from 1.6µgkg-1 ww (wet weight) to below the limit of reporting of 0.3µgkg-1 ww, with concentrations generally decreasing toward the lower reaches of the estuary. The sample of C. gigas tested had a PFOS concentration of 0.71µgkg-1 ww that was consistent with concentrations observed in nearby S. glomerata. For harvest size (50-60g) S. glomerata, both holding contaminated oysters in a depuration system, and relocation to a non-contaminated area, saw significant reductions in the tissue PFOS concentrations. For oysters held in a depuration system, PFOS depurated at a rate of 0.008h-1 (0.004-0.019h-1; 90% CI), which corresponded with a depuration half-life of 87h (35-155h; 90%). A more conservative model (fitted to data that assumed concentrations

Increased Risk of Heterotopic Ossification Following Revision Hip Arthroplasty for Periprosthetic Joint Infection.

BACKGROUND: To investigate whether surgery for Periprosthetic Joint Infection (PJI) of the hip, the number of procedures and their duration contribute to risk of Heterotopic Ossification formation. METHODS: 56 patients with hip PJI undergoing one-stage (10) or two-stage (46) exchange arthroplasty were matched to 112 patients undergoing revision arthroplasty for aseptic failure based on age, gender, body mass index (BMI), surgical approach (all direct lateral) and date of surgery (2006-2013). Patients with Paget's disease and ankylosing spondylitis, or preoperative HO were excluded. Perioperative pain management included use of the anti-inflammatory medications in all patients without prophylactic radiotherapy. Six-month postoperative radiographs were reviewed based on Brooker classification. RESULTS: The incidence of overall HO in PJI and aseptic groups was 84% (47/56) and 11% (12/112), respectively. High grade HO (grades 3 and 4) in PJI and aseptic groups were 25% (24/56) and 4% (4/112), respectively. PJI was an independent risk factor for HO in the multivariate analysis (odds ratio of 9.3, 95% CI: 2.9-29.9, P<0.001). CONCLUSION: Patients undergoing surgical treatment of hip PJI seem to be at increased risk of developing HO compared to aseptic failure. HO prophylaxis regimens may be recommendable in eligible patients undergoing surgical intervention for PJI of the hip. LEVEL OF EVIDENCE: IV.

Adult exposure to ocean acidification is maladaptive for larvae of the Sydney rock oyster Saccostrea glomerata in the presence of multiple stressors.

Parental effects passed from adults to their offspring have been identified as a source of rapid acclimation that may allow marine populations to persist as our surface oceans continue to decrease in pH. Little is known, however, whether parental effects are beneficial for offspring in the presence of multiple stressors. We exposed adults of the oyster Saccostrea glomerata to elevated CO2 and examined the impacts of elevated CO2 (control = 392; 856 µatm) combined with elevated temperature (control = 24; 28°C), reduced salinity (control = 35; 25) and reduced food concentration (control = full; half diet) on their larvae. Adult exposure to elevated CO2 had a positive impact on larvae reared at elevated CO2 as a sole stressor, which were 8% larger and developed faster at elevated CO2 compared with larvae from adults exposed to ambient CO2 These larvae, however, had significantly reduced survival in all multistressor treatments. This was particularly evident for larvae reared at elevated CO2 combined with elevated temperature or reduced food concentration, with no larvae surviving in some treatment combinations. Larvae from CO2-exposed adults had a higher standard metabolic rate. Our results provide evidence that parental exposure to ocean acidification may be maladaptive when larvae experience multiple stressors.