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Fluid injection into geological formations for energy resource development frequently induces (micro)seismicity. Moderate- to large-magnitude induced earthquakes may cause injuries and/or economic loss, with the consequence of jeopardizing the operation and future development of these geo-energy projects. To achieve an improved understanding of the mechanisms of induced seismicity, develop forecasting tools and manage the associated risks, it is necessary to carefully examine seismic data from reported cases of induced seismicity and the parameters controlling them. However, these data are challenging to gather together and are time-consuming to collate as they come from different disciplines and sources. Here, we present a publicly available, multi-physical database of injection-induced seismicity (Kivi et al., 2022a; 10.20350/digitalCSIC/14813), sourced from an extensive review of published documents. Currently, it contains 158 datasets of induced seismicity caused by various subsurface energy-related applications worldwide. Each dataset covers a wide range of variables, delineating general site information, host rock properties, in situ geologic and tectonic conditions, fault characteristics, conducted field operations, and recorded seismic activities. We publish the database in flat-file formats (i.e., .xls and .csv tables) to facilitate its dissemination and utilization by geoscientists while keeping it directly readable by computer codes for convenient data manipulation. The multi-disciplinary content of this database adds unique value to databases focusing only on seismicity data. In particular, the collected data aim at facilitating the understanding of the spatiotemporal occurrence of induced earthquakes, the diagnosis of potential triggering mechanisms, and the development of scaling relations of maximum possible earthquake magnitudes and operational parameters. The database will boost research in seismic hazard forecasting and mitigation, paving the way f

Automatic underwater vehicle hull Design optimization is a complex engineering process for generating a UUV hull with optimized properties on a given requirement. First, it involves the integration of involved computationally complex engineering simulation tools. Second, it needs integration of a sample efficient optimization framework with the integrated toolchain. To this end, we integrated the CAD tool called FreeCAD with CFD tool openFoam for automatic design evaluation. For optimization, we chose Bayesian optimization (BO), which is a well-known technique developed for optimizing time-consuming expensive engineering simulations and has proven to be very sample efficient in a variety of problems, including hyper-parameter tuning and experimental design. During the optimization process, we can handle infeasible design as constraints integrated into the optimization process. By integrating domain-specific toolchain with AI-based optimization, we executed the automatic design optimization of underwater vehicle hull design. For empirical evaluation, we took two different use cases of real-world underwater vehicle design to validate the execution of our tool.

Geothermal energy is a growing renewable resource that generates electricity and heat by circulating fluids in the subsurface. Assessing reservoir quality and quantifying the amount of heat, fluid volume and circulation is key to determining a project’s economic viability. Where natural permeability is too low, high-pressure injection of fluids into the subsurface can be used to improve reservoir quality and increase the storage and production capacity of the system. These are called Enhanced Geothermal Systems (EGS). Unfortunately, the injection of fluids at EGS sites has resulted in some perceived induced seismic events (>Mw 2.5), such as in Soultz, France and Basel, Switzerland. Shaking from the events caused alarm in surrounding regions and shut down development of the projects (Majer et al., 2007). Evaluating induced seismic hazard during EGS project planning is key to mitigating property damage and negative public perception that can shut down a site. EGS site reservoir models are developed to fully characterize the geologic and geomechanical properties to aid treatment planning and to assess seismic hazards. These use a wide variety of data about previous seismic activity, geology, stress state, and poroelastic properties. Integrating the large variety of data is difficult due to the uncertainty and assumptions made in the data, processing, and modelling., We develop a probabilistic assessment system using a combination of unsupervised hybrid k-means clustering (Rogova, et al. 2009) and supervised learning to aid processing of multi-disciplinary data sets. Temperature, pressure, stress, porosity and permeability data from the FORGE EGS test site in Utah (Moore et al., 2019) is used to build and test the system. This data is mapped in 3D and unsupervised clustering identifies initial clusters of patterns using the suite of input data. The initial data clusters are combined and assigned a final grouping using a pairwise combination method within the framework of the Transferable Belief Model, which is used to quantitatively represent the level of support and ignorance for combined cluster assignments. Initial results classify the site into 3 to 5 clusters that correspond to variations in the input properties. The 3 clusters map classify into (1) high (2) medium, and (3) low values of pressure, temperature, and stress magnitude. The run with 5 clusters divides the high medium and low clusters into 2 additional clusters. Cluster 2 and 5 have overlapping values, though the latter has a greater range of values. The system developed in this work represents the first part of a planned system to aid the prediction of induced seismic events in EGS. The second part of the planned system will use the identified property clusters in combination with fracture logs, treatment data, and microseismic events to identify likely regions of fracture growth.

Geothermal systems require reliable reservoir characterization to increase the production of this renewable source of heat and electricity. We apply state-of-the-art Physics Informed Neural Networks (PINN) to model the fluid pressure evolution p(x,y,t) for the 2D reservoir domain. We set up a PINN for inferring p(x,y,t) by constraining an Artificial Neural Network’s (ANN) loss function with data and physics. In addition to time series measurements at the well location, we enforce the initial condition and boundary conditions. Since we lack observation points within deep geothermal reservoirs, we minimize the residual of a mass balance partial differential equation (PDE) on random collocation points inside the domain. Inside the PDE two data-driven ANNs are used to estimate the heterogeneous permeability field of the fractured reservoir k(x,y) and the flow rate at the injection borehole Q(t). We then train a separate ANN to estimate p(x,y,t), which leads to more stable modeling results than training these ANNs in parallel. We fine-tune these models by adapting the concept of dimensionless PDEs to the specific scaling requirements of ANNs. In addition, the weighting of loss terms is tested for several adaptive weighting schemes to find the optimum results. Our preliminary results indicate that with PINN and our current setup, we can infer the fluid pressure evolution for a high permeability contrast inside the reservoir while having only a small amount of observation points inside the domain.

Aim: Describe the reported lived experiences of nurses who have participated at any stage of voluntary assisted dying (VAD), from the initial request to the end of life. Design: A qualitative meta-synthesis. Data sources: Databases searched were CINAHL, MEDLINE, Emcare, Scopus and PsycInfo. The search was undertaken in September 2021 with no date limitations. Qualitative studies were considered if published in English, reported primary data analysis of nurses' experiences who had been involved in VAD and reported direct quotes from nurses. Review methods: Qualitative studies meeting the selection criteria were critically appraised, then an open card-sort method was applied. Quotes from nurses were organized to group similar experiences, constructing themes and metaphors across studies as a new understanding of nurses' experiences of VAD. Results: Eight studies were included. Three major themes were constructed: An orderly procedure, reflecting the need for structure to feel adequately prepared; A beautiful death, reflecting the autonomy the patient exercised when choosing VAD facilitated an exceptionally positive death; and Psychological and emotional impact, where nurses recognized the emotional and ethical weight that they carried for them-selves and the team when undertaking VAD. Conclusion: Nurses may benefit from clear policy, supervision and communication training to support them as countries transition to providing VAD services. Policy provides nurses with confidence that they are undertaking the steps of VAD correctly and provides a layer of emotional protection. Communication training specific to VAD is necessary to prepare nurses to recognize their own emotional experiences when responding to the needs of the patient and their family. Impact: VAD is increasingly becoming a legal option that nurses are encountering in their professional practice. Understanding nurses' experiences of being involved in VAD is required to support nurses in countries where VAD

The interactions most supportive of positive child development take place in moments of close contact with others. In the earliest years of life, a child's caregivers are the primary partners in these important interactions. Little is known about the patterns of real-life physical interactions between children and their caregivers, in part due to an inability to measure these interactions as they occur in real time. We have developed a wearable, infrastructure-free device (TotTag) used to dynamically and unobtrusively measure physical proximity between children and caregivers in real time. We present a case-study illustration of the TotTag with data collected over two (12-hour) days each from two families: a family of four (30-month-old son, 61-month-old daughter, 37-year-old father, 37-year-old mother), and a family of three (12-month-old daughter, 35-year-old-father, 33-year-old mother). We explored patterns of proximity within each parent-child dyad and whether close proximity would indicate periods in which increased opportunity for developmentally critical interactions occur. Each child also wore a widely used wearable audio recording device (LENA) to collect time-synced linguistic input. Descriptive analyses reveal wide variability in caregiver-child proximity both within and across dyads, and that the amount of time spent in close proximity with a caregiver is associated with the number of adult words and conversational turns to which a child was exposed. This suggests that variations in proximity are linked to-though, critically, not synonymous with-the quantity of a child's exposure to adult language. Potential implications for deepening the understanding of early caregiver-child interactions are discussed.

AIM: Describe the reported lived experiences of nurses who have participated at any stage of voluntary assisted dying (VAD), from the initial request to the end of life. DESIGN: A qualitative meta-synthesis. DATA SOURCES: Databases searched were CINAHL, MEDLINE, Emcare, Scopus and PsycInfo. The search was undertaken in September 2021 with no date limitations. Qualitative studies were considered if published in English, reported primary data analysis of nurses' experiences who had been involved in VAD and reported direct quotes from nurses. REVIEW METHODS: Qualitative studies meeting the selection criteria were critically appraised, then an open card-sort method was applied. Quotes from nurses were organized to group similar experiences, constructing themes and metaphors across studies as a new understanding of nurses' experiences of VAD. RESULTS: Eight studies were included. Three major themes were constructed: An orderly procedure, reflecting the need for structure to feel adequately prepared; A beautiful death, reflecting the autonomy the patient exercised when choosing VAD facilitated an exceptionally positive death; and Psychological and emotional impact, where nurses recognized the emotional and ethical weight that they carried for themselves and the team when undertaking VAD. CONCLUSION: Nurses may benefit from clear policy, supervision and communication training to support them as countries transition to providing VAD services. Policy provides nurses with confidence that they are undertaking the steps of VAD correctly and provides a layer of emotional protection. Communication training specific to VAD is necessary to prepare nurses to recognize their own emotional experiences when responding to the needs of the patient and their family. IMPACT: VAD is increasingly becoming a legal option that nurses are encountering in their professional practice. Understanding nurses' experiences of being involved in VAD is required to support nurses in countries where VAD i

Mercury (Hg) and especially its methylated species (MeHg) are toxic chemicals that contaminate humans via the consumption of seafood. The most recent UNEP Global Mercury Assessment stressed that Mediterranean populations have higher Hg levels than people elsewhere in Europe. The present Critical Review updates current knowledge on the sources, biogeochemical cycling, and mass balance of Hg in the Mediterranean and identifies perspectives for future research especially in the context of global change. Concentrations of Hg in the Western Mediterranean average 0.86 ± 0.27 pmol L–1 in the upper water layer and 1.02 ± 0.12 pmol L–1 in intermediate and deep waters. In the Eastern Mediterranean, Hg measurements are in the same range but are too few to determine any consistent oceanographical pattern. The Mediterranean waters have a high methylation capacity, with MeHg representing up to 86% of the total Hg, and constitute a source of MeHg for the adjacent North Atlantic Ocean. The highest MeHg concentrations are associated with low oxygen water masses, suggesting a microbiological control on Hg methylation, consistent with the identification of hgcA-like genes in Mediterranean waters. MeHg concentrations are twice as high in the waters of the Western Basin compared to the ultra-oligotrophic Eastern Basin waters. This difference appears to be transferred through the food webs and the Hg content in predators to be ultimately controlled by MeHg concentrations of the waters of their foraging zones. Many Mediterranean top-predatory fish still exceed European Union regulatory Hg thresholds. This emphasizes the necessity of monitoring the exposure of Mediterranean populations, to formulate adequate mitigation strategies and recommendations, without advising against seafood consumption. This review also points out other insufficiencies of knowledge of Hg cycling in the Mediterranean Sea, including temporal variations in air–sea exchange, hydrothermal and cold seep inputs, point so

Mercury (Hg) and especially its methylated species (MeHg) are toxic chemicals that contaminate humans via the consumption of seafood. The most recent UNEP Global Mercury Assessment stressed that Mediterranean populations have higher Hg levels than people elsewhere in Europe. The present Critical Review updates current knowledge on the sources, biogeochemical cycling, and mass balance of Hg in the Mediterranean and identifies perspectives for future research especially in the context of global change. Concentrations of Hg in the Western Mediterranean average 0.86 ± 0.27 pmol L–1 in the upper water layer and 1.02 ± 0.12 pmol L–1 in intermediate and deep waters. In the Eastern Mediterranean, Hg measurements are in the same range but are too few to determine any consistent oceanographical pattern. The Mediterranean waters have a high methylation capacity, with MeHg representing up to 86% of the total Hg, and constitute a source of MeHg for the adjacent North Atlantic Ocean. The highest MeHg concentrations are associated with low oxygen water masses, suggesting a microbiological control on Hg methylation, consistent with the identification of hgcA-like genes in Mediterranean waters. MeHg concentrations are twice as high in the waters of the Western Basin compared to the ultra-oligotrophic Eastern Basin waters. This difference appears to be transferred through the food webs and the Hg content in predators to be ultimately controlled by MeHg concentrations of the waters of their foraging zones. Many Mediterranean top-predatory fish still exceed European Union regulatory Hg thresholds. This emphasizes the necessity of monitoring the exposure of Mediterranean populations, to formulate adequate mitigation strategies and recommendations, without advising against seafood consumption. This review also points out other insufficiencies of knowledge of Hg cycling in the Mediterranean Sea, including temporal variations in air–sea exchange, hydrothermal and cold seep inputs, point so

Reliable reservoir characterization of the strata, fractures, and hydraulic properties is needed to determine the energy storage capacity of geothermal systems. We apply the state-of-the-art Physics-Informed Neural Networks (PINN) to model subsurface flow in a geothermal reservoir. A PINN can incorporate any physical laws that can be described by partial differential equations. We obtain a ground truth dataset by running a virtual pumping-well test in the numerical code “Code_Bright”. This model consists of a low-permeability rock matrix, intersected by high- permeability fractures. We approximate the reservoir permeability with an Artificial Neural Network (ANN) denoted by . Secondly, we model the fluid pressure evolution with the PINN by informing it about the experimental well-testing data. Since observation wells are sparse in space (only the injection well in our case), we feed into a hydraulic mass balance equation. The residual of this equation enforces the loss function of for random collocation points inside the domain. Our results indicate that the ANN is able to approximate even for a high permeability contrast. In addition, the successful interpolation of proves the PINN is a promising method for matching field data with physical laws. In contrast to numerical models PINNs shift the computational efforts toward the training, while reducing the resources needed for the forward evaluation. Nevertheless, training a 3D reservoir model can hardly be achieved on an ordinary workstation since the training data may include several millions of entries. In addition, computational costs increase due to the inclusion of multiphysics processes in the PINN. We plan to prepare the PINN model for training using parallelized GPUs to significantly increase the training speed of the ANNs.

The Castor underground gas storage (UGS) project in the offshore depleted Amposta oilfield, SE of the Ebro delta, was halted by the Spanish government following the detection of over 500 seismic events after the start of injection on 3 September 2013. The number of detected seismic events rapidly increased following the start of injection and continued for two months afterwards. Events range in magnitudes from 0.7 to 4.2 mbLg and were felt in populated areas on the east coast of Spain. Previous coupled two-phase flow and geomechanical modeling of triggering mechanisms in the Castor sequence are dependent on accurate event locations (e.g., Vilarrasa et al., 2022). A range of event depths from 2 km to 10 km and source mechanisms are reported for the seismic sequence at Castor (e.g., Gaite et al., 2016), which have multiple interpretations. The lack of constraint on event depth is due to monitor array asymmetry and a poorly constrained velocity model (Vilarrasa et al., 2022). Seismometers are primarily located on the east coast of Spain with only 2 more than 100 km SE of the field. The velocity models used for locating events are typically derived from CRUST2.0 models and are on the scale of 10s of km. More accurate depths will aid in selecting the appropriate interpretation. Constraints on depth resolution uncertainty are calculated for events recorded near the Castor UGS project. We simulate seismic wave propagation at locations calculated for the largest recorded events in the vicinity of the Castor platform using the velocity model from Palomeras et al. (2017) to build a simplified 2D SpecFem model. To test the sensitivity of the event location to the velocity model we introduce a perturbation layer, 1km thick, with a 10% perturbation in the P- and S- velocities and compare the modeled waveforms to the recorded waveforms. By changing the depth of the perturbation layer, we can determine the range of depths where the velocity model and located event are best constra

Geothermal energy is a renewable source of heat and electricity which can contribute to Europe's future energy independence. To scale this technology, reservoir characterization in geothermal projects needs to become more reliable. A major challenge here is to identify the spatial distribution of distinct rock strata and their hydraulic properties from well-pumping tests. These experiments are carried out to infer permeability, but offer only a few observation points in space and require large extrapolation through inversion. Physics Informed Neural Networks (PINN) are a recently emerging approach that can seamlessly incorporate pumping test data while enforcing accordance with physical laws in the domain between observation points. We implement this concept via the loss function of an Artificial Neural Network (ANN) that consists of several distinct loss terms for observational data and a mass balance equation. In this study, we represent the heterogeneous permeability k(x) and the spatiotemporal fluid pressure distribution p(x,t) each by an ANN, respectively. We compare our regression output to a virtual experimental dataset from the numerical code "OpenGeoSys". The results indicate that our PINN model can approximate k(x) and interpolate p(x,t) in a 1D domain for a setup of real-world material parameters. In this way, PINN proves as a promising method that deserves further investigation to also provide reliable performance at the reservoir scale.

Geothermal energy, an important source of renewable energy, generates electricity from circulating fluids in the Earth’s crust. Enhanced Geothermal Systems (EGS) use high pressure injection of fluids into the subsurface to improve geothermal reservoir quality in regions with poor natural permeability and increase the storage and production capacity of the system. Documented cases of induced seismicity at EGS sites raise concerns about the risk of felt seismic events (>Mw=2) such as in Soultz, France and Basel, Switzerland that caused alarm in the surrounding regions and shut down development in the latter case (Majer et al. 2007). Evaluating induced seismic hazard and risk during EGS project planning is key to mitigating potential property damage and negative public perception of EGS projects. Seismic hazard assessment uses a variety of data about previous seismic activity, geology, structure, stress state, and poroelastic rock properties of the surrounding formations. This data is used to develop models to predict treatment response and if seismicity will be generated. Integrating a variety of data is difficult due to the uncertainty and assumptions made in the data, processing, and modelling. We develop an assessment system using a combination of unsupervised hybrid k-means clustering (Rogova et al. 2009) and supervised learning to aid processing of a multi-disciplinary data set. Unsupervised clustering finds patterns in each data type, then data clusters are combined and assigned a final grouping using a pairwise combination method within the framework of the Transferable Belief Model, which is used to quantitatively represent the level of support and ignorance for combined cluster assignments. Public data from the FORGE EGS site in Utah, USA is used in testing and development, including regional seismic catalogs, maps of faults, geologic structure, and borehole logs.

Mercury (Hg) and especially its methylated species (MeHg) are toxic chemicals that contaminate humans via the consumption of seafood. The most recent UNEP Global Mercury Assessment stressed that Mediterranean populations have higher Hg levels than people elsewhere in Europe. The present Critical Review updates current knowledge on the sources, biogeochemical cycling, and mass balance of Hg in the Mediterranean and identifies perspectives for future research especially in the context of global change. Concentrations of Hg in the Western Mediterranean average 0.86 ± 0.27 pmol L–1 in the upper water layer and 1.02 ± 0.12 pmol L–1 in intermediate and deep waters. In the Eastern Mediterranean, Hg measurements are in the same range but are too few to determine any consistent oceanographical pattern. The Mediterranean waters have a high methylation capacity, with MeHg representing up to 86% of the total Hg, and constitute a source of MeHg for the adjacent North Atlantic Ocean. The highest MeHg concentrations are associated with low oxygen water masses, suggesting a microbiological control on Hg methylation, consistent with the identification of hgcA-like genes in Mediterranean waters. MeHg concentrations are twice as high in the waters of the Western Basin compared to the ultra-oligotrophic Eastern Basin waters. This difference appears to be transferred through the food webs and the Hg content in predators to be ultimately controlled by MeHg concentrations of the waters of their foraging zones. Many Mediterranean top-predatory fish still exceed European Union regulatory Hg thresholds. This emphasizes the necessity of monitoring the exposure of Mediterranean populations, to formulate adequate mitigation strategies and recommendations, without advising against seafood consumption. This review also points out other insufficiencies of knowledge of Hg cycling in the Mediterranean Sea, including temporal variations in air–sea exchange, hydrothermal and cold seep inputs, point so

We present a comprehensive, publicly accessible database of injection-induced seismicity. The database is sourced from a comprehensive review of more than 500 published documents and contains information for 158 cases of induced earthquakes from around the world. The collected earthquakes are associated with a variety of geoenergy applications, which can be broadly categorized into geologic gas storage, geothermal energy development, shale gas fracturing, research projects and wastewater disposal. The compilation comprises more than 70 variables, including general project information, host rock properties, ‎in situ site characteristics, fault attributes, operational parameters, and recorded seismicity data (both overall seismic activities and the largest event sequence). The developed database opens up opportunities for improved understanding of the causative mechanisms of injection-induced seismicity and advancing on seismic hazard forecasting and mitigation.

The interactions most supportive of positive child development take place in moments of close contact with others. In the earliest years of life, a child's caregivers are the primary partners in these important interactions. Little is known about the patterns of real-life physical interactions between children and their caregivers, in part due to an inability to measure these interactions as they occur in real time. We have developed a wearable, infrastructure-free device (TotTag) used to dynamically and unobtrusively measure physical proximity between children and caregivers in real time. We present a case-study illustration of the TotTag with data collected over two (12-hour) days each from two families: a family of four (30-month-old son, 61-month-old daughter, 37-year-old father, 37-year-old mother), and a family of three (12-month-old daughter, 35-year-old-father, 33-year-old mother). We explored patterns of proximity within each parent-child dyad and whether close proximity would indicate periods in which increased opportunity for developmentally critical interactions occur. Each child also wore a widely used wearable audio recording device (LENA) to collect time-synced linguistic input. Descriptive analyses reveal wide variability in caregiver-child proximity both within and across dyads, and that the amount of time spent in close proximity with a caregiver is associated with the number of adult words and conversational turns to which a child was exposed. This suggests that variations in proximity are linked to-though, critically, not synonymous with-the quantity of a child's exposure to adult language. Potential implications for deepening the understanding of early caregiver-child interactions are discussed.

The interactions most supportive of positive child development take place in moments of close contact with others. In the earliest years of life, a child's caregivers are the primary partners in these important interactions. Little is known about the patterns of real-life physical interactions between children and their caregivers, in part due to an inability to measure these interactions as they occur in real time. We have developed a wearable, infrastructure-free device (TotTag) used to dynamically and unobtrusively measure physical proximity between children and caregivers in real time. We present a case-study illustration of the TotTag with data collected over two (12-hour) days each from two families: a family of four (30-month-old son, 61-month-old daughter, 37-year-old father, 37-year-old mother), and a family of three (12-month-old daughter, 35-year-old-father, 33-year-old mother). We explored patterns of proximity within each parent-child dyad and whether close proximity would indicate periods in which increased opportunity for developmentally critical interactions occur. Each child also wore a widely used wearable audio recording device (LENA) to collect time-synced linguistic input. Descriptive analyses reveal wide variability in caregiver-child proximity both within and across dyads, and that the amount of time spent in close proximity with a caregiver is associated with the number of adult words and conversational turns to which a child was exposed. This suggests that variations in proximity are linked to-though, critically, not synonymous with-the quantity of a child's exposure to adult language. Potential implications for deepening the understanding of early caregiver-child interactions are discussed.

Type I signal peptidase, with its vital role in bacterial viability, is a promising but underexploited antibacterial drug target. In the light of steadily increasing rates of antimicrobial resistance, we have developed novel macrocyclic lipopeptides, linking P2 and P1' by a boronic ester warhead, capable of inhibiting Escherichia coli type I signal peptidase (EcLepB) and exhibiting good antibacterial activity. Structural modifications of the macrocyclic ring, the peptide sequence and the lipophilic tail led us to 14 novel macrocyclic boronic esters. It could be shown that macrocyclization is well tolerated in terms of EcLepB inhibition and antibacterial activity. Among the synthesized macrocycles, potent enzyme inhibitors in the low nanomolar range (e.g. compound 42f, EcLepB IC50 = 29 nM) were identified also showing good antimicrobial activity (e.g. compound 42b, E. coli WT MIC = 16 μg/mL). The unique macrocyclic boronic esters described here were based on previously published linear lipopeptidic EcLepB inhibitors in an attempt to address cytotoxicity and hemolysis. We show herein that structural changes to the macrocyclic ring influence both the cytotoxicity and hemolytic activity suggesting that the P2 to P1' linker provide means for optimizing off-target effects. However, for the present set of compounds we were not able to separate the antibacterial activity and cytotoxic effect., N.S. and L.L. share first authorship.

Redox conditions and organic matter control marine methylmercury (MeHg) production. The Black Sea is the world's largest and deepest anoxic basin and is thus ideal to study Hg species along the extended redox gradient. Here we present new dissolved Hg and MeHg data from the 2013 GEOTRACES MEDBlack cruise (GN04_leg2) that we integrated into a numerical 1‐D model, to track the fate and dynamics of Hg and MeHg. Contrary to a previous study, our new data show highest MeHg concentrations in the permanently anoxic waters. Observed MeHg/Hg percentage (range 9–57%) in the anoxic waters is comparable to other subsurface maxima in oxic open‐ocean waters. With the modeling we tested for various Hg methylation and demethylation scenarios along the redox gradient. The results show that Hg methylation must occur in the anoxic waters. The model was then used to simulate the time evolution (1850–2050) of Hg species in the Black Sea. Our findings quantify (1) inputs and outputs of HgT (~31 and ~28 kmol yr−1) and MeHgT (~5 and ~4 kmol yr−1) to the basin, (2) the extent of net demethylation occurring in oxic (~1 kmol yr−1) and suboxic water (~6 kmol yr−1), (3) and the net Hg methylation in the anoxic waters of the Black Sea (~11 kmol yr−1). The model was also used to estimate the amount of anthropogenic Hg (85–93%) in the Black Sea.

Redox conditions and organic matter control marine methylmercury (MeHg) production. The Black Sea is the world's largest and deepest anoxic basin and is thus ideal to study Hg species along the extended redox gradient. Here we present new dissolved Hg and MeHg data from the 2013 GEOTRACES MEDBlack cruise (GN04_leg2) that we integrated into a numerical 1‐D model, to track the fate and dynamics of Hg and MeHg. Contrary to a previous study, our new data show highest MeHg concentrations in the permanently anoxic waters. Observed MeHg/Hg percentage (range 9–57%) in the anoxic waters is comparable to other subsurface maxima in oxic open‐ocean waters. With the modeling we tested for various Hg methylation and demethylation scenarios along the redox gradient. The results show that Hg methylation must occur in the anoxic waters. The model was then used to simulate the time evolution (1850–2050) of Hg species in the Black Sea. Our findings quantify (1) inputs and outputs of HgT (~31 and ~28 kmol yr−1) and MeHgT (~5 and ~4 kmol yr−1) to the basin, (2) the extent of net demethylation occurring in oxic (~1 kmol yr−1) and suboxic water (~6 kmol yr−1), (3) and the net Hg methylation in the anoxic waters of the Black Sea (~11 kmol yr−1). The model was also used to estimate the amount of anthropogenic Hg (85–93%) in the Black Sea.

Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. < br > < br > The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results., National Science Foundation (U.S.) (Grant 1053648)

Mercury (Hg) is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission). Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011-2015) in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes., National Science Foundation (U.S.) (Grant 1053648)

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere are not yet well understood. We extended the regional atmospheric chemistry model WRF-Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low-concentration, slowly degrading semivolatile compounds. The WRF-Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity, i.e. phenanthrene, chrysene and benzo[a]pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF-Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new species and to correct the transport problems can be applied to other newly implemented species in WRF-Chem.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere are not yet well understood. We extended the regional atmospheric chemistry model WRF-Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low-concentration, slowly degrading semivolatile compounds. The WRF-Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity, i.e. phenanthrene, chrysene and benzo[a]pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF-Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new species and to correct the transport problems can be applied to other newly implemented species in WRF-Chem.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere are not yet well understood. We extended the regional atmospheric chemistry model WRF-Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low-concentration, slowly degrading semivolatile compounds. The WRF-Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity, i.e. phenanthrene, chrysene and benzo[a]pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF-Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new species and to correct the transport problems can be applied to other newly implemented species in WRF-Chem.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere are not yet well understood. We extended the regional atmospheric chemistry model WRF-Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low-concentration, slowly degrading semivolatile compounds. The WRF-Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity, i.e. phenanthrene, chrysene and benzo[a]pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF-Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new species and to correct the transport problems can be applied to other newly implemented species in WRF-Chem.

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air–surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM ∕ GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM ∕ GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation

Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3 ∕ OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat b

Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere are not yet well understood. We extended the regional atmospheric chemistry model WRF-Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low-concentration, slowly degrading semivolatile compounds. The WRF-Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity, i.e. phenanthrene, chrysene and benzo[a]pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF-Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new species and to correct the transport problems can be applied to other newly implemented species in WRF-Chem.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere have not yet been well understood. We extended the regional atmospheric chemistry model WRF/Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low concentrated, slowly degrading semivolatile compounds. The WRF/Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity i.e., phenanthrene, chrysene and benzo(a)pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF/Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new tracers and to correct the transport problems can be applied to other newly implemented tracers in WRF/Chem.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants, with increasing emissions in pace with economic development in East Asia, but their distribution and fate in the atmosphere have not yet been well understood. We extended the regional atmospheric chemistry model WRF/Chem (Weather Research Forecast model with Chemistry module) to comprehensively study the atmospheric distribution and the fate of low concentrated, slowly degrading semivolatile compounds. The WRF/Chem-PAH model reflects the state-of-the-art understanding of current PAHs studies with several new or updated features. It was applied for PAHs covering a wide range of volatility and hydrophobicity i.e., phenanthrene, chrysene and benzo(a)pyrene, in East Asia. Temporally highly resolved PAH concentrations and particulate mass fractions were evaluated against observations. The WRF/Chem-PAH model is able to reasonably well simulate the concentration levels and particulate mass fractions of PAHs near the sources and at a remote outflow region of East Asia, in high spatial and temporal resolutions. Sensitivity study shows that the heterogeneous reaction with ozone and the homogeneous reaction with the nitrate radical significantly influence the fate and distributions of PAHs. The methods to implement new tracers and to correct the transport problems can be applied to other newly implemented tracers in WRF/Chem.

Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air–surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM ∕ GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM ∕ GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation

Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3 ∕ OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat b

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM=GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM=GEM ratios from spring to summer. O₃ chemistry does not predict significant seasonal variation of Hg oxidation. He

White seabass (Atractoscion nobilis) are a popular sportfish (also fished commercially) whose numbers have declined dramatically since the early 1950s. Prompted by the stock’s troubles, the California Department of Fish and Game established the Ocean Resources Enhancement and Hatchery Program in the 1980s. Since 1986, Hubbs-SeaWorld Research Institute’s seabass hatchery in Carlsbad, California has released about 744,000 fish.

Demand for seafood on a global scale is projected to increase by 70 percent in the next 30 years, though most fisheries are at or beyond their sustainable yields and many are in decline (Botsford et al. 1997). Fisheries management must be augmented by new strategies for protecting and enhancing marine resources, such as “no-take” marine reserves (Allison et al. 1998; Hastings and Botsford 1999) or enhancing natural stocks through artificial hatchery propagation. Despite criticisms from conservationists and fisheries biologists alike (e.g. Meffe 1992; MacCall 1989), large-scale hatchery supplementation programs are already in place for many anadromous and marine fisheries (Travis et al. 1998), and in Japan, a substantial fraction of marine production is attributable to enhancement programs (Masuda and Tsukamoto 1998). The global extent of enhancement of wild fisheries is poorly documented, however, especially for marine species (A.F. Born, A.J. Immink, and D.M. Bartley, FAO Fisheries, pers. com.). In Japan, to take just one example, nearly 70 marine species are supplemented, some at very high levels. To date there have been very few analyses of the potential genetic impact of these marine supplementation programs.

The Pacific oyster occurs on all continents but Antarctica (Mann 1979) and for the past several years has had the highest annual production of any freshwater or marine organism (4.2 million metric tons in 2002, worth $3.5 billion; FAO 2004). About 92 million pounds of Pacific oyster meat were produced on the West Coast in 2000, with a farm-gate value of nearly $70 million (Toba and Chew 1999). West Coast production exceeds the harvest of Eastern oysters on either the Gulf or Atlantic Coasts, primarily because diseases have wiped out those natural stocks. As the Pacific oyster does not naturally reproduce along much of the West Coast, seed was imported from Japan for decades (Chew 1984). In the early 1980s, however, the industry adopted hatchery techniques and now relies mainly on hatchery seed. This sets the stage not only for commercial breeding programs, which industry identifies as a top priority (Pacific Shellfish Institute 1999), but also for development in the future of a mature seed industry servicing global markets.