Native Oyster Research Articles

Oyster extractivism in the Amazon: characterization and perception of extractivists on the conservation of natural banks

The objectives of this study were to identify extractivists working in the region of Curuçá, Pará, Brazil, to evaluate the perception of these workers on the conservation and exploitation of natural oyster stocks. Applying snowball sampling, semistructured questionnaires were applied in the period from September 2019 to January 2020, resulting in 38 interviewed extractivists. Of the 38 respondents, 50% were older than 40 years, 78.9% were men, and oyster extractivism was the main source of income for 65.8%. In addition, 94.7% lived in the city of Curuçá, and 36.8% worked as extractivists for 7 to 11 years. The majority reported never having received any training on oyster collection or oyster bank conservation. The extractivists reported that their greatest challenge was collection sites. Lack of training was a risk factor for collecting during the rainy season (OR=1.52), while having received training was a protective factor for collecting seeds (OR=0.64). Additionally, 94.7% of the respondents reported an increase in oyster mortality in the rainy season. Encouraging extractivists to organize into associations or cooperatives with the support of public development policies and providing training focused on sustainable extraction can contribute to the conservation of natural oyster banks by preventing damage to the natural ecosystem.

Assessing the ecological functioning and biodiversity of remnant native flat oyster (Ostrea angasi) reefs in temperate southeast Australia

Oyster reefs are critically endangered coastal habitats which provide valuable ecosystems services. Despite their importance, there remains a significant knowledge gap in our understanding of how oyster and sediment characteristics influence the ecological functioning and biodiversity of remnant Australian flat oyster (Ostrea angasi) reefs. To inform restoration efforts, we assessed relationships between community respiration rates (CR), inorganic nitrogen fluxes, filtration rates, biodiversity, and oyster morphometrics as well as sediment conditions for three remanent flat oyster reefs (Oyster Cove, Ralphs Bay, and Quarantine Bay) in southeast Tasmania. Additionally, we explored relationships between net denitrification, and flat oyster morphometrics and sediment conditions at one of the sites (Ralphs Bay) in southeast Tasmania. We observed positive relationships between CR, inorganic nitrogen fluxes, filtration rates, and live flat oyster biomass, as well as between the richness and biomass of associated taxa and total flat oyster biomass (both tissue and shell including dead shell), across all three locations. We also found an increase in net denitrification associated with live oyster biomass at one of the oyster reefs (Ralphs Bay). The CR, inorganic nitrogen fluxes, filtration rates, diversity of taxa and biomass of bivalves and flat oyster biomass was higher at Ralphs Bay, which has the most intact reef, compared to the other two locations. In contrast to other studies, the organic and silt content of the sediment showed limited influence on CR, inorganic nitrogen fluxes, filtration rates and net denitrification. CR, and inorganic nitrogen fluxes in these flat oyster reefs were like other restored and natural oyster reefs globally, but net denitrification, filtration rate and taxonomic richness exceeded those previously observed globally. These results highlight the important role of oyster biomass in enhancing water quality and biodiversity. Burgeoning flat oyster reef restoration initiatives should prioritise the enhancement of both live oyster populations and dead shells to recover their associated ecological functions and biological diversity.

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.

Wet ball milling activated oyster shells for multifunctional slow-release compound fertilizer production

Slow-release fertilizers have been known to boost crop yields, but their high cost and slow degradation make them less practical for use. In this study, oyster shell (OS) was modified by mechanical ball milling with monosodium glutamate (MSG) wastewater as an activator to prepare activated oyster shell (AOS) with an average particle size of 32.7 nm. Compared to natural oyster shell (NOS), the AOS increased water-soluble Ca by 22 times, expanded the average desorption pore size by 155 %, enhanced the specific surface area by 9 times, and improved the total pore volume by 1587 %. AOS was mixed with traditional fertilizers and extruded to develop a new type of activated oyster-based slow-release compound fertilizer (AOF). Physical effects mainly controlled the slow-release ability of AOF. AOS formed vaterite with a large peak shape, high strength, and well-defined crystal structure, providing more binding sites for NH4+, HPO42−, K+, Ca2+ and Mg2+. In addition, AOS was rich in Ca-OH and Mg-OH, which increased the potential for ligand exchange with fertilizer ions, which further improved the chemical slow-release properties of AOF. The AOF continuously releases N, P, K, Ca, and Mg nutrients over a period exceeding 70 days. The nutrient release behavior in AOF was accurately described by the logistic equation, the Elovich equation, and the parabolic diffusion equation. AOF increased the dry weight of green plum by 190 % and the yield by 61 %. The AOF prepared in this study proved to be an innovative and environmentally sustainable slow-release fertilizer.

Suspended culture of the Manabí oyster Crassostrea cf. corteziensis in a tropical estuary

Grow-out of the Manabí oyster (Crassostrea cf. corteziensis) under suspended culture conditions from the Chone River Estuary (Manabí, Ecuador) was evaluated. The culture was established in lanterns with 50 oysters/floor for seven months (July 2022 to February 2023) using juveniles (34.9±6.2 mm) collected from natural oyster beds in the same estuary. The growth and survival, as well as environmental variables in the culture site, were monitored. The growth in the shell dimension was continuous, reaching high rates during October and November. At the end of the study, 86.7±6.68 mm anteroposterior length, 110.7±19.04 g dry mass of the whole organism (with 3.7±0.67 g soft tissue), and survival of 92.6±2.62 % were obtained. No association was observed between the patterns of the growth curves and those of the environmental parameters; however, the decrease of body mass (during February 2023) was associated with increased temperature, decreased salinity, and lower phytoplankton content. Oysters of marketable size (80 mm) were obtained after seven months of culture. The results suggest the biological feasibility of cultivating the Manabí oyster C. cf. corteziensis in the Chone River Estuary, which could be an emerging species for aquaculture in Ecuador and the tropical American Pacific.

Natural zinc-rich oyster peptides ameliorate DSS-induced colitis via antioxidation, anti-inflammation, intestinal barrier repair, microbiota modulation, and SCFA accumulation

Natural oyster zinc-rich peptide (OZP) was extracted and purified. The higher zinc concentration in natural OZP may be closely related to the high zinc affinity of amino acids containing Lys, His, Cys, Val, Arg and Ser residues. FTIR analysis indicated that amino, amide, carboxyl and carbonyl groups may contribute to the binding sites for zinc and peptides. Administration of OZP ameliorated the symptoms of DSS-induced ulcerative colitis (UC) in mice, including weight loss, colonic damage, mucosal edema, goblet cell exhaustion and crypt disappearance. Natural OZP suppressed oxidative stress by significantly reducing the level of NO, MDA and MPO as well as increasing SOD activity. The anti-inflammatory effects of OZP were associated with the inhibition of TLR4/NF-κB pathways by diminishing NF-κB, TLR4, COX-2, iNOS, TNF-α, IL-6 and IFN-γ and elevating IL-10. By promoting mucus secretion, repairing goblet cells and enhancing the expression of tight junction proteins including occludin, claudin-1 and ZO-1, natural OZP maintained the intestinal barrier function. Furthermore, natural OZP regulated the microbial composition by remarkedly enhancing the beneficial microbial abundance like Faecalibaculum, Odoribacter and Anaerostipes, which in turn led to a significant increase in SCFA production. Collectively, natural OZP exerted the synergistic capacity to protect against DSS-induced UC by improving antioxidation and anti-inflammation, repairing intestinal barrier and modulating intestinal microbiota and SCFA.

Exploring high intertidal refugia as an approach for the restoration of an intertidal oyster

Marine organisms frequently inhabit intertidal zones that serve as refuges from predation and competition but are not optimal physiologically. Restoration practitioners working with intertidal species may similarly have to consider whether restoration success will be greater where conditions are more benign (usually lower in the intertidal) or where negative biotic interactions are reduced (usually higher in the intertidal). In cases where a target species has greater desiccation tolerance than its enemies, restoration may be more successful higher in the intertidal zone, despite potential performance trade-offs. In many US West Coast estuaries, non-native drill species can decimate native oyster populations, posing a challenge to restoration. Given that native Olympia oysters Ostrea lurida should be better able to withstand tidal emersion than the non-native Atlantic oyster drill Urosalpinx cinerea, we explored using the high intertidal as a refuge from predation as a potential restoration technique. Using surveys and a field experiment, we investigated the recruitment, growth, and survival of oysters as well as drill abundance and predation over 3 tidal elevations. Oysters recruited and survived equally well at +0.1, +0.5, and +0.8 m mean lower low water, but juvenile oyster growth decreased with increasing elevation. In our experiment, predation on oysters was lower at the highest elevation than at low and mid elevations, but in natural populations there was a near complete absence of O. lurida at any elevation where U. cinerea was present. This suggests that a higher tidal elevation refuge is not a viable approach for oyster restoration in our study area.

The Pacific oyster reproduction is affected by early-life exposure to environmental pesticide mixture: A multigenerational study

Pesticides threat marine organisms worldwide. Among them, the Pacific oyster is a bivalve mollusc model in marine ecotoxicology. A large body of literature already stated on the multiple-scale effects pesticides can trigger in the Pacific oyster, throughout its life cycle and in a delayed manner. In particular, reproductive toxicity is of major concern because of its influence on population dynamics. However, past studies mostly investigated pesticide reprotoxicity as a direct effect of exposure during gametogenesis or directly on gametes and little is known about the influence of an early embryo exposure on the breed capacity. Therefore, we studied delayed and multigenerational consequences through gametogenesis features (i.e. sex ratio, glycogen content, gene expression) and reproductive success in two consecutive oyster generations (F0 and F1) exposed to an environmentally-relevant pesticide mixture (sum nominal concentration: 2.85 μg.L−1) during embryo-larval development (0–48 h post fertilization, hpf). In the first generation, glycogen content increased in exposed individuals and the expression of some gametogenesis target genes was modified. The reproductive success measured 48 hpf was higher in exposed individuals. A multigenerational influence was observed in the second generation, with feminisation, acceleration of gametogenesis processes and the sex-specific modification of glycogen metabolism in individuals from exposed parents. This study is the first to highlight the delayed effects on reproduction induced by an early exposure to pesticides, and its multigenerational implications in the Pacific oyster. It suggests that environmental pesticide contamination can have impacts on the recruitment and the dynamics of natural oyster populations exposed during their embryo-larval phase.

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.

Reproductive cycle of the mangrove oyster Crassostrea rhizophorae (Guilding, 1828) in Delta do Parnaíba, Brazil

This study describes some aspects of the reproductive biology of the native oyster Crassostrea rhizophorae in the Delta do Parnaíba estuary, located between the states of Maranhão and Piauí, Brazil. The oysters were acquired from landings at Porto dos Tatus (Ilha Grande - PI) between June 2017 and May 2018. Approximately 50 individuals per month (n=611) with an average total shell length of 74.44 mm (±14.31 SD) were collected for analysis of gonadal development and condition index and correlated with temporal variations in local rainfall. The C. rhizophorae population in the Parnaíba Delta estuary showed a sex ratio of 2.18 females to 1 male and continuous reproduction. The condition index (CI) values in the dry period were higher, coinciding with a greater proportion of individuals in the gametogenesis and pre-spawning stages. In the rainy season, there was a reduction in the CI as a result of animals in the gamete release stage.

The history of the European native oyster Ostrea edulis in Northern Irish waters and the four phases of resource exploitation

An in-depth history of the European native oyster in Northern Irish waters has been absent from international and regional peer-reviewed publications. The knowledge of historical losses and a need to recover ecosystems for habitat and biodiversity purposes are primary drivers in an urgency to restore Ostrea edulis. However, a comprehensive record of O. edulis in Northern Ireland is required to assist with this work. The authors compiled a list of relevant references from grey material, rare historical archives, library collections, government reports and peer-reviewed publications. Archival reviews have been tabulated into a timeline, which documents site location, exploitation, sites of significant interest and socio-economic histories of the coastal communities who relied on the oyster. The reference material identified four distinctive phases of exploitation whereby harvesting transits from personal use to commercialization, collapse and then restoration. The study revealed that O. edulis harvests in the early 1800s in Northern Ireland were predominantly destined for export to supply collapsing stocks throughout Britain. Fishing was intense with the fishery closed by 1903. However, the species has proved to be extremely resilient with small artisanal fisheries still in existence today. This research will offer habitat managers guidance in relation to site selection and anthropogenic pressures when restoring the European flat oyster to the iconic historical beds of the Northern Irish Sea loughs.

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.

Restored oyster reefs and living shorelines can augment predator trophic dynamics

Coastal habitat loss has led to declines in many higher trophic level predators. These declines can be mitigated through habitat restoration, which putatively enhances predator populations and trophic dynamics by creating foraging opportunities in reestablished habitat, but this lacks empirical support. Here, we assess the prediction restored coastal habitat supports sportfish feeding relationships similar to natural habitat, at restored oyster reefs (Crassostrea virginica) and living shoreline habitats in Florida, U.S.A. Stable isotopes and gut contents were analyzed from young sportfish (i.e. predatory fish targeted by anglers) collected at control and restored sites for up to 3 years. The influence of habitat features, predator size, and prey availability on carbon and nitrogen isotope values were examined using a model species (mangrove/gray snapper [Lutjanus griseus]). In summary, sportfish species had distinct isotopic values, consuming similar prey but in different proportions between habitats. Prey abundance and richness, and reef height were influential predictors of L. griseus stable isotope values, with restored reefs contributing to their diet more than controls according to Bayesian mixing models. The trophic niche area of L. griseus and their predominant prey achieved trophic equivalence between restored and natural oyster reefs within 1 year following restoration. Stabilized living shorelines attained trophic equivalency to natural shorelines, but may take longer to accrue prey for some species. These findings generate fundamental ecological knowledge and actionable science, including targets, timelines, and indicator species, that natural resource managers and restoration practitioners can use to assess trophic structure and success of coastal habitat restoration.

Combining ecology and technology to kick‐start oyster reef restoration

Techniques that enhance the recruitment of foundation species to restoration sites can inform the ecological development of the restored habitat. However, techniques are often considered in isolation, potentially overlooking synergies from combining them. Native oyster reefs have been lost worldwide, resulting in restoration efforts in systems that are often recruitment limited, or where recruiting oysters must spatially compete with opportunistic species. Here, we present a field‐based study that combines ecological knowledge on positive species interactions with novel acoustic technology, both of which are demonstrated to boost oyster recruitment in isolation, to test whether their interaction synergistically enhances the early larval recruitment that drives oyster reef development. At three sites across a 20 ha oyster reef restoration in southern Australia, we used self‐made speakers to broadcast healthy reef soundscapes that attract oysters and combine this with artificial kelp that facilitates oyster recruitment by suppressing competitive species (turfing algae). The combination of acoustic enrichment and artificial kelp increased oyster recruitment to the topside of substrate (326.98% increase), whereas only acoustic enrichment increased recruitment to the underside of substrate (126.95% increase). Our findings suggest that the combination of multiple techniques and their interactive effects might boost the early stages of reef development, providing proof‐of‐concept that these approaches can help oysters to build and bind reefs (i.e. recruit to the topside and underside, respectively). By combining ecology with technology during the first stages of a developing reef restoration, we show the potential value of these novel approaches to kick‐start the recovery of lost oyster reefs.

Setting the stones to restore and monitor European flat oyster reefs in the German North Sea

Abstract Ecological restoration includes specific technical phases over the course of an ecosystem recovery process. In the marine environment and for oyster reef restoration, the installation and implementation of pilot reefs close the gap between feasibility studies with small‐scale experiments and designated upscaling for marine conservation measures. Against this background, this study presents the design, planning and installation of the first pilot oyster reef in offshore sublittoral regions of the North Sea. The work was conducted as part of marine protected area management in the Natura 2000 site Borkum Reef Ground in the German Bight, in the area of historical offshore oyster grounds. It includes logistical considerations, material selection, methodology for reef base construction and deployment of European flat oysters Ostrea edulis as spat‐on‐shell, young and adult single seed oysters, and spat‐on‐reef, as well as the development of an efficient monitoring approach for reef‐associated biodiversity. Native Oyster Restoration Alliance monitoring methodologies, such as underwater visual census and seabed images were selected, tested and successfully adapted for the pilot oyster reef and study site. The evaluation and optimization of offshore sublittoral oyster reef monitoring are presented here, and biodiversity metrics are put into perspective with data from recent and historical studies. Results show a few mobile fauna species (e.g., fish and decapods) as first colonizers after reef construction. One year later, biodiversity increased due to a larger number of invertebrate and fish species. However, the pilot oyster reef community still represents an early recolonization stage, with lower biodiversity than historical records. This study presents a proof of concept for the design, planning and construction of an offshore oyster reef and indicates stages in the recovery process. Strategies to optimize and to complement reef‐monitoring in challenging environments are discussed, emphasizing additional molecular and functional analyses for future assessments.

The Effect of the CCERS STEM + C Project on Information Technology Efficacy in Terms of Gender and Grade Level

Information technology has become ubiquitous in the 21st Century. Acquiring the skills and confidence to navigate the computational arena is all but obligatory for educational and professional success. Underrepresentation of women in the wide variety of fields associated with information technology is an authentic concern for both the individual and society as a whole. Various studies have emphasized the importance of stronger representative of marginalized groups to bolster creative thinking and a variety of perspectives. The CCERS STEM + C Program is a long-term hands-on environmental restoration project that has been embedded in the New York City Department of Education public schools. Students work to restore the native oyster population to New York Harbor through both field work and working with large sets of data on the open-access platform. One of the several areas studied throughout this program is the motivation and self-efficacy of the students, especially students who are underrepresented in the STEM and technology fields. Student surveys were initiated by 764 students with 513 participants and non-participants completing the survey. Aimed at eliciting levels of several self-reported factors, the survey included a subscale measuring levels of confidence in technological abilities. Results of the survey indicated that 9th grade female students have a higher level of self-efficacy and motivation than female students in the later high school grade levels. These results are consistent with the waning motivation and interest of female students in technology and STEM found in other studies.

Rotational fishing enables biodiversity recovery and provides a model for oyster (Ostrea edulis) habitat restoration.

Reefs formed by Ostrea edulis, the European native oyster, are among many biogenic habitats that have declined globally. European oyster habitats are now rare, and undisturbed examples have not been described. As more is understood of the ecosystem services provided by the reefs, oyster restoration efforts are on the rise, becoming a more prominent component of Europe's portfolio of marine conservation practices. It is therefore important to establish the relationship between the development of oyster reefs and their associated biotic community if the biodiversity benefits are to be accurately predicted and the progress of restoration projects assessed. The Loch Ryan oyster fishery in Southwest Scotland is the last of its type and uses a rotational harvest system where different areas are fished each year and then left for six years before they are fished again. This provided an opportunity to study the effect of oyster reef development and biodiversity gain at different stages of habitat recovery. In this study three treatments were surveyed for faunal biodiversity, oyster shell density and oyster shell percentage cover. Treatments were plots that had been harvested one year before, two years before, and six years before the study. The treatments were surveyed with SCUBA using a combination of video transects and photo quadrats. Oyster shell density, oyster shell percent cover and macrofaunal biodiversity differed significantly between treatments, with the highest values observed in the six-year treatment. Shell density was 8.5 times higher in the six-year treatment compared to the one-year treatment, whilst Shannon-Wiener's diversity was 60.5% higher, and Margalef's richness 68.8% higher. Shell density and percent cover had a significant positive relationship with macrofaunal biodiversity. This is probably due to the provision of increased structural complexity in the matrix of live and dead oyster shells. Projecting forward the trend of biodiversity increase in relation to time since disturbance indicates that full recovery would take approximately ten years in which time diversity (Shannon-Wiener) would probably have doubled. The findings from the present study indicate the probable biodiversity benefits of oyster habitat restoration and a cost-effective metric (shell density) to judge progress in restoration projects.

Development of PCR rapid detection method for Listeria monocytogenes in oysters

To develop a polymerase chain reaction(PCR) method for rapid detection of Listeria monocytogenes in oysters without pre-enrichment. The combination of β-cyclodextrin and bentonite-coated activated carbon was used to remove PCR inhibitors from oyster samples, and the target gene inlB was used for the PCR subsequently. The specificity, sensitivity, and application of the developed method were verified, and the stability and application of the reagents stored under cryopreservation conditions were evaluated. The specificity of the developed PCR method was 100% for the detection of 130 target bacterial strains and 63 non-target bacterial strains. The method reduced the time required for Listeria monocytogenes detection to 4 h without pre-enrichment, and the detection limit was 10 CFU/25 g. The method was consistent with the conventional culture method on the detection rate and viable bacteria detection rate of Listeria monocytogenes in natural oyster samples(the coincidence rate was 100%). Additionally, the reagents could be used normally after storing at-20 ℃ for at least one year. The PCR method developed in this study has high specificity and sensitivity, and can be used for rapid, accurate detection of Listeria monocytogenes in oysters.

Distribution and source assignments of polycyclic aromatic and aliphatic hydrocarbons in sediments and biota of the Lafayette River, VA.

The Lafayette River comprises a tidal sub-estuary constrained by an urban watershed that is bounded by residential areas at its upper reaches and port activity at its mouth. We determined the concentrations and distributions of polycyclic aromatic hydrocarbons (PAHs) and aliphatic n-alkanes across 19 sites from headwaters to river mouth in surface sediments (0-2cm). Potential atmospheric sources were investigated through the analysis of wet and dry deposition samples and intact coals from a major export terminal nearby. The potential consequences for human consumption were examined through analysis of native oyster (Crassostrea virginica) and blue crab tissues (Callinectes sapidus). A suite of up to 66 parent and alkyl-substituted PAHs were detected in Lafayette sediments with total concentrations ranging from 0.75 to 39.00µgg-1 dry wt. Concentrations of aliphatic n-alkanes (n-C16 - n-C31) ranged from 4.94 to 40.83μgg-1 dry wt. Source assignment using diagnostic ratios and multivariate source analysis suggests multiple sources contribute to the hydrocarbon signature in this metropolitan system with automotive and atmospheric transport of coal dust as the major contributors. Oyster tissues showed similar trends as PAHs observed in sediments indicating similar sources to water column particles which ultimately accumulate in sediments with crabs showing altered distributions as a consequence of metabolism.

Site selection for European native oyster (Ostrea edulis) habitat restoration projects: An expert‐derived consensus

Abstract The European native oyster (Ostrea edulis) is a threatened keystone species which historically created extensive, physically complex, biogenic habitats throughout European seas. Overfishing and direct habitat destruction, subsequently compounded by pollution, invasive species, disease, predation and climate change have resulted in the functional extinction of native oyster habitat across much of its former range. Although oyster reef habitat remains imperilled, active restoration efforts are rapidly gaining momentum. Identifying appropriate sites for habitat restoration is an essential first step in long‐term project success. In this study, a three‐round Delphi process was conducted to determine the most important factors to consider in site selection for European native oyster habitat restoration projects. Consensus was reached on a total of 65 factors as being important to consider in site selection for European native oyster habitat restoration projects. In addition to the abiotic factors typically included in habitat suitability models, socio‐economic and logistical factors were found to be important. Determining the temporal and spatial variability of threats to native oyster habitat restoration and understanding the biotic factors present at a proposed restoration site also influence the potential for project scale‐up and longevity. This list guides site selection by identifying: a shortlist of measurable factors which should be considered; the relevant data to collect; topics for discussion in participatory mapping processes; information of interest from the existing body of local ecological knowledge; and factors underpinning supportive and facilitating regulatory frameworks.