Environmental performance of blue foods.

Fish and other aquatic foods (blue foods) present an opportunity for more sustainable diets1,2. Yet comprehensive comparison has been limited due to sparse inclusion of blue foods in environmental impact studies3,4 relative to the vast diversity of production5. Here we provide standardized estimates of greenhouse gas, nitrogen, phosphorus, freshwater and land stressors for species groups covering nearly three quarters of global production. We find that across all blue foods, farmed bivalves and seaweeds generate the lowest stressors. Capture fisheries predominantly generate greenhouse gas emissions, with small pelagic fishes generating lower emissions than all fed aquaculture, but flatfish and crustaceans generating the highest. Among farmed finfish and crustaceans, silver and bighead carps have the lowest greenhouse gas, nitrogen and phosphorus emissions, but highest water use, while farmed salmon and trout use the least land and water. Finally, we model intervention scenarios and find improving feed conversion ratios reduces stressors across all fed groups, increasing fish yield reduces land and water use by up to half, and optimizing gears reduces capture fishery emissions by more than half for some groups. Collectively, our analysis identifies high-performing blue foods, highlights opportunities to improve environmental performance, advances data-poor environmental assessments, and informs sustainable diets.

Pharmaceutical pollution of the world's rivers.

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world's rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals.

In Vivo Mercury (De)Methylation Metabolism in Cephalopods under Different pCO2 Scenarios.

This work quantified the accumulation efficiencies of Hg in cuttlefish, depending on both organic (MeHg) and inorganic (Hg(II)) forms, under increased pCO2 (1600 µatm). Cuttlefish were fed with live shrimps injected with two Hg stable isotopic tracers (Me202Hg and 199Hg(II)), which allowed for the simultaneous quantification of internal Hg accumulation, Hg(II) methylation, and MeHg demethylation rates in different organs. Results showed that pCO2 had no impact on Hg bioaccumulation and organotropism, and both Hg and pCO2 did not influence the microbiota diversity of gut and digestive gland. However, the results also demonstrated that the digestive gland is a key organ for in vivo MeHg demethylation. Consequently, cuttlefish exposed to environmental levels of MeHg could exhibit in vivo MeHg demethylation. We hypothesize that in vivo MeHg demethylation could be due to biologically induced reactions or to abiotic reactions. This has important implications as to how some marine organisms may respond to future ocean change and global mercury contamination.

Bioaccumulation of inorganic and organic mercury in the cuttlefish Sepia officinalis: Influence of ocean acidification and food type.

The bioaccumulation of mercury (Hg) in marine organisms through various pathways has not yet been fully explored, particularly in cephalopods. This study utilises radiotracer techniques using the isotope 203Hg to investigate the toxicokinetics and the organotropism of waterborne inorganic Hg (iHg) and dietary inorganic and organic Hg (methylHg, MeHg) in juvenile common cuttlefish Sepia officinalis. The effect of two contrasting CO2 partial pressures in seawater (400 and 1600 µatm, equivalent to pH 8.08 and 7.54, respectively) and two types of prey (fish and shrimp) were tested as potential driving factors of Hg bioaccumulation. After 14 days of waterborne exposure, juvenile cuttlefish showed a stable concentration factor of 709 ± 54 and 893 ± 117 at pH 8.08 and 7.54, respectively. The accumulated dissolved i203Hg was depurated relatively rapidly with a radiotracer biological half-life (Tb1/2) of 44 ± 12 and 55 ± 16 days at pH 8.08 and 7.54, respectively. During the whole exposure period, approximately half of the i203Hg was found in the gills, but i203Hg also increased in the digestive gland. When fed with 203Hg-radiolabelled prey, cuttlefish assimilated almost all the Hg provided (>95%) independently of the prey type. Nevertheless, the prey type played a major role on the depuration kinetics with Hg Tb1/2 approaching infinity in fish fed cuttlefish vs. 25 days in shrimp fed cuttlefish. Such a difference is explained by the different proportion of Hg species in the prey, with fish prey containing more than 80% of MeHg vs. only 30% in shrimp. Four days after ingestion of radiolabelled food, iHg was primarily found in the digestive organs while MeHg was transferred towards the muscular tissues. No significant effect of pH/pCO2 variation was observed during both the waterborne and dietary exposures on the bioaccumulation kinetics and tissue distribution of i203Hg and Me203Hg. Dietary exposure is the predominant pathway of Hg bioaccumulation in juvenile cuttlefish.

Global Plastic Pollution Observation System to Aid Policy.

Plastic pollution has become one of the most pressing environmental challenges and has received commensurate widespread attention. Although it is a top priority for policymakers and scientists alike, the knowledge required to guide decisions, implement mitigation actions, and assess their outcomes remains inadequate. We argue that an integrated, global monitoring system for plastic pollution is needed to provide comprehensive, harmonized data for environmental, societal, and economic assessments. The initial focus on marine ecosystems has been expanded here to include atmospheric transport and terrestrial and freshwater ecosystems. An earth-system-level plastic observation system is proposed as a hub for collecting and assessing the scale and impacts of plastic pollution across a wide array of particle sizes and ecosystems including air, land, water, and biota and to monitor progress toward ameliorating this problem. The proposed observation system strives to integrate new information and to identify pollution hotspots (i.e., production facilities, cities, roads, ports, etc.) and expands monitoring from marine environments to encompass all ecosystem types. Eventually, such a system will deliver knowledge to support public policy and corporate contributions to the relevant United Nations (UN) Sustainable Development Goals (SDGs).

Effects of Virgin Micro- and Nanoplastics on Fish: Trends, Meta-Analysis, and Perspectives.

Environmental plastic pollution is a major ecological and societal concern today. Over the past decade, a broad range of laboratory and experimental studies have complemented field observations in the hope of achieving a better understanding of the fate and impact of micro- and/or nanoplastics (MP/NP) on diverse organisms (e.g., birds, fish, and mammals). However, plastic pollution remains challenging to monitor in the environment and to control under laboratory conditions, and plastic particles are often naturally or experimentally co-contaminated with diverse chemical pollutants. Therefore, our understanding of the effects of virgin MP/NP in freshwater and marine fish is still limited. Here, we performed a systematic review of the most up-to-date literature on the effects of virgin MP/NP on fish under laboratory conditions. A total of 782 biological endpoints investigated in 46 studies were extracted. Among these endpoints, 32% were significantly affected by exposure to virgin MP/NP. More effects were observed for smaller plastic particles (i.e., size ≤20 µm), affecting fish behavioral and neurological functions, intestinal permeability, metabolism, and intestinal microbiome diversity. In addition, we propose suggestions for new research directions to lead toward innovative, robust, and scientifically sound experiments in this field. This review of experimental studies reveals that the toxicity of virgin MP/NP on fish should be more systematically evaluated using rigorous laboratory-based methods and aims toward a better understanding of the underlying mechanisms of this toxicity to fish.

No Effect of Polystyrene Microplastics on Foraging Activity and Survival in a Post-larvae Coral-Reef Fish, Acanthurus triostegus.

Microplastics (MP) are ubiquitous in the marine environment and have been shown to alter the behaviour of some species due to potential neurotoxic effect. However, very little is known on the effect of this stressor on behavioural responses of early and more vulnerable life stages. This study explores the effects of polystyrene MP (90 µm diameter) on the foraging activity of newly settled surgeonfish Acanthurus triostegus and on their survival facing predators. Exposure to a high concentration of 5 MP particles per mL (5 MP mL-1) for 3, 5 and 8 days did not alter their foraging activity nor their susceptibility to predation. This suggests that short-term exposures to reportedly high MP concentrations have negligible effects on the behaviour of newly settled A. triostegus. Nevertheless, responses to MP can be highly variable, and further research is needed to determine potential ecological effects of MP on reef fish populations during early-life stages.

Does aquaculture add resilience to the global food system?

Aquaculture is the fastest growing food sector and continues to expand alongside terrestrial crop and livestock production. Using portfolio theory as a conceptual framework, we explore how current interconnections between the aquaculture, crop, livestock, and fisheries sectors act as an impediment to, or an opportunity for, enhanced resilience in the global food system given increased resource scarcity and climate change. Aquaculture can potentially enhance resilience through improved resource use efficiencies and increased diversification of farmed species, locales of production, and feeding strategies. However, aquaculture's reliance on terrestrial crops and wild fish for feeds, its dependence on freshwater and land for culture sites, and its broad array of environmental impacts diminishes its ability to add resilience. Feeds for livestock and farmed fish that are fed rely largely on the same crops, although the fraction destined for aquaculture is presently small (∼4%). As demand for high-value fed aquaculture products grows, competition for these crops will also rise, as will the demand for wild fish as feed inputs. Many of these crops and forage fish are also consumed directly by humans and provide essential nutrition for low-income households. Their rising use in aquafeeds has the potential to increase price levels and volatility, worsening food insecurity among the most vulnerable populations. Although the diversification of global food production systems that includes aquaculture offers promise for enhanced resilience, such promise will not be realized if government policies fail to provide adequate incentives for resource efficiency, equity, and environmental protection.

Bioconcentration of Ag, Cd, Co, Mn and Zn in the Mangrove Oyster (Crassostrea gasar) and Preliminary Human Health Risk Assessment: A Radiotracer Study.

Bioaccumulation kinetics of five dissolved metals were determined in the mangrove oyster Crassostrea gasar, using corresponding radiotracers ((54)Mn, (57)Co, (65)Zn, (109)Cd and (110m)Ag). Additionally, their bioaccessibility to human consumers was estimated. Results indicated that over a 14-day exposure (54)Mn and (57)Co were linearly concentrated in oysters whereas (109)Cd, (65)Zn and (110m)Ag were starting to saturate (steady-state not reached). Whole-body concentration factors at 14 days (CF14d in toto) ranged from 187 ± 65 to 629 ± 179 with the lowest bioconcentration capacity for Co and the highest for Ag. Depuration kinetics were best described by a double-exponential model with associated biological half-lives ranging from 26 days (Ag) to almost 8 months (Zn and Cd). Bioaccessible fraction of the studied elements was estimated using in vitro digestions, which suggested that oysters consumed seasoned with lemon enhanced the accessibility of Cd, Mn and Zn to human consumers, but not Ag and Co.

Metal bioconcentration in the scleractinian coral Stylophora pistillata: investigating the role of different components of the holobiont using radiotracers.

Bioconcentration kinetics of five metals (Ag, Cd, Co, Mn, and Zn) were determined in the scleractinian coral Stylophora pistillata (entire symbiotic association vs. cultured symbionts), using radiotracer techniques. Among contrasting element behaviors observed in S. pistillata, the highest efficiency of concentration and retention was observed for Ag in the symbiotic association (CFss reaching 5000 and T b½>1 year). Predominant proportion of this metal was found associated with the skeleton whereas the other metals were mainly present in the coral tissues (including host tissues and symbionts). A 96-h exposure of cultured symbionts (isolated zooxantellae from S. pistillata) indicated that they displayed a very high potential for metal bioconcentration (higher by 1 to 3 orders of magnitude compared to the skeleton). In addition, among the five elements investigated, Ag had the highest concentration factor in the cultured symbionts. Contrasting kinetic characteristics of skeleton vs. tissues offer interesting implications for biomonitoring purposes. Indeed, the skeleton was shown to display stable metal concentrations after an exposure (long retention time) and thereby allows recording contamination event on the long term, whereas the concentrations within coral tissues rapidly increased during the exposure and dropped when non-contaminating conditions were restored, allowing information on the current (short term) contamination status. The present study confirms that the coral can be seen as a two-compartment box model for metal bioconcentration: the tissues sensus latto as a first box governing metal entrance (with a crucial role played by the symbionts) and the skeleton as a second box where metal detoxification (storage) is taking place; the first box also depurates toward the environment when non-contaminating conditions are restored.

Interspecific and geographical variations of trace metal concentrations in cephalopods from Tunisian waters.

The concentrations of six metals (Ag, Cd, Cu, Hg, Pb, and Zn) were investigated and compared in three tissues (arms, digestive gland, and mantle) of three cephalopod species from the Tunisian waters: the common octopus (Octopus vulgaris), the common cuttlefish (Sepia officinalis), and the European squid (Loligo vulgaris). Whatever the species or the sites, the digestive gland displayed the highest concentrations of Ag, Cd, Cu, Pb, and Zn, highlighting its major role in their bioaccumulation and detoxification. This is also true for Hg but only for the digestive gland of O. vulgaris. Muscle from the arms and the mantle contained thus relatively low trace metal concentrations except for Hg in L. vulgaris and S. officinalis. Geographic comparison of metal concentrations in Tunisian cephalopods from three locations indicates that higher concentrations of Ag, Pb, and Hg were observed in cephalopods from northern and eastern coasts, whereas the highest Cd levels were detected in the southeastern, reflecting different conditions of exposure. Comparing the trace element concentrations between species, Ag, Cd, Cu, Hg, and Zn concentrations were the highest in the digestive gland of octopuses. This may be related to the differences in ecological features and swimming behavior among different cephalopod species. Effects of length and sex on metal levels were also considered, indicating a limited influence of sex on metal concentration.

Regional assessment of the historical trends of mercury in sediment cores from Wider Caribbean coastal environments.

Spatial and temporal variations of mercury (Hg) concentrations, enrichment, and potential ecological risks were studied in a suite of lead-210 (210Pb) dated sediment cores from 13 Wider Caribbean Region coastal environments. Broad variability of Hg concentrations (19-18761 ng g-1) was observed, encompassing even background levels (38-100 ng g-1). Most Hg concentration profiles exhibited a characteristic upward trend, reaching their peak values in the past two decades. Most of the sediment sections, showing from moderately to very severe Hg enrichment, were found in cores from Havana Bay and Sagua River Estuary (Cuba), Port-au-Prince Bay (Haiti), and Cartagena Bay (Colombia). These were also the most seriously contaminated sites, which can be considered regional Hg 'hotspots'. Both Havana Bay and Port-au-Prince Bay reportedly receive waste from large cities with populations exceeding 2 million inhabitants, and watersheds affected by high erosion rates. The records from the Sagua River Estuary and Cartagena Bay reflected historical Hg contamination associated with chloralkali plants, and these sites are of very high ecological risk. These results constitute a major contribution to the scarce regional data on contaminants in the Wider Caribbean Region and provide reference information to support the evaluation of the effectiveness of the Minamata Convention.

To what extent do food preferences explain the trophic position of heterotrophic and mixotrophic microbial consumers in a Sphagnum peatland?

Although microorganisms are the primary drivers of biogeochemical cycles, the structure and functioning of microbial food webs are poorly studied. This is the case in Sphagnum peatlands, where microbial communities play a key role in the global carbon cycle. Here, we explored the structure of the microbial food web from a Sphagnum peatland by analyzing (1) the density and biomass of different microbial functional groups, (2) the natural stable isotope (δ(13)C and δ(15)N) signatures of key microbial consumers (testate amoebae), and (3) the digestive vacuole contents of Hyalosphenia papilio, the dominant testate amoeba species in our system. Our results showed that the feeding type of testate amoeba species (bacterivory, algivory, or both) translates into their trophic position as assessed by isotopic signatures. Our study further demonstrates, for H. papilio, the energetic benefits of mixotrophy when the density of its preferential prey is low. Overall, our results show that testate amoebae occupy different trophic levels within the microbial food web, depending on their feeding behavior, the density of their food resources, and their metabolism (i.e., mixotrophy vs. heterotrophy). Combined analyses of predation, community structure, and stable isotopes now allow the structure of microbial food webs to be more completely described, which should lead to improved models of microbial community function.

Extruded polystyrene microplastics as a source of brominated flame retardant additives in the marine environment: long-term field and laboratory experiments.

Microplastics (MPs) in the environment have become a global concern, not only for the physical effects of the plastic particles themselves but also for being vectors of chemical additives. In this context, little is known about the ability of MPs, particularly extruded polystyrene microplastics (XPS-MPs), to release organic chemical additives in the marine environment. In this study, a series of field and laboratory experiments were carried out to determine the leaching behaviour of organic additives including brominated flame retardants from XPS-MPs into seawater. The conducted experiments confirmed a rapid release of bisphenol A (BPA), 2,4,6-tribromophenol (TBP), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane diastereoisomers (α-, ß-, and γ-HBCDD) from the studied MPs followed by a slower rate of release over time. The effects of environmental factors on the leaching rates of these additives were also examined. Increasing Dissolved Organic Matter (DOM) concentrations and the temperature of the seawater enhanced the release of additives by increasing their solubility and polymer flexibility. In contrast, pH tested at 7, 7.5 and 8 was found to have a minor effect on additives leaching; and salinity negatively affected the leaching rate likely due to their reduced solubility and reduced diffusion from the MPs. The present study provides empirical evidence of the behaviour of XPS-MPs as a source of organic additives in the marine environment that merit further investigation.

Environmental footprints of farmed chicken and salmon bridge the land and sea.

Food production, particularly of fed animals, is a leading cause of environmental degradation globally.1,2 Understanding where and how much environmental pressure different fed animal products exert is critical to designing effective food policies that promote sustainability.3 Here, we assess and compare the environmental footprint of farming industrial broiler chickens and farmed salmonids (salmon, marine trout, and Arctic char) to identify opportunities to reduce environmental pressures. We map cumulative environmental pressures (greenhouse gas emissions, nutrient pollution, freshwater use, and spatial disturbance), with particular focus on dynamics across the land and sea. We found that farming broiler chickens disturbs 9 times more area than farming salmon (∼924,000 vs. ∼103,500 km2) but yields 55 times greater production. The footprints of both sectors are extensive, but 95% of cumulative pressures are concentrated into <5% of total area. Surprisingly, the location of these pressures is similar (85.5% spatial overlap between chicken and salmon pressures), primarily due to shared feed ingredients. Environmental pressures from feed ingredients account for >78% and >69% of cumulative pressures of broiler chicken and farmed salmon production, respectively, and could represent a key leverage point to reduce environmental footprints. The environmental efficiency (cumulative pressures per tonne of production) also differs geographically, with areas of high efficiency revealing further potential to promote sustainability. The propagation of environmental pressures across the land and sea underscores the importance of integrating food policies across realms and sectors to advance food system sustainability.

Microplastic-sorbed persistent organic pollutants in coastal Mediterranean Sea areas of Tunisia.

Microplastics (MPs) are emerging pollutants of global concern due to their pervasiveness, high sorption ability for persistent organic pollutants (POPs) and direct and indirect toxicity to marine organisms, ecosystems, as well as humans. As one of the major coastal interfaces, beaches are considered among the most affected ecosystems by MPs pollution. The morphological characteristics of MPs (pellets and fragments) collected from four beaches along the Tunisian coast and sorbed POPs, including polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), were investigated in this study. The results showed that the MPs varied greatly in color, polymer composition and degradation degree. The color varied from colored to transparent and the most prevalent polymer identified using Raman spectroscopy was polyethylene. Scanning electron microscope (SEM) images exhibited various surface degradation features including cavities, cracks, attached diatom remains, etc. The concentrations of Σ12PCBs over all beaches ranged from 14 to 632 ng g-1 and 26 to 112 ng g-1 in the pellets and fragments, respectively, with a notable presence and dominance of highly-chlorinated PCBs such as CB-153 and -138. Among the OCPs, γ-HCH is the only compound detected with concentrations ranging from 0.4 to 9.7 ng g-1 and 0.7 to 4.2 ng g-1 in the pellets and fragments, respectively. Our findings indicate that MPs found on the Tunisian coast may pose a chemical risk to marine organisms as the concentrations of PCBs and γ-HCH in most of the analysed samples exceeded the sediment-quality guidelines (SQG), especially the effects range medium (ERM) and the probable effects level (PEL). As the first report of its kind, the information gathered in this study can serve as the baseline and starting point for future monitoring work for Tunisia and neighbouring countries, as well as for stakeholders and coastal managers in decision-making processes.

Two decades of seawater acidification experiments on tropical scleractinian corals: Overview, meta-analysis and perspectives.

Ocean acidification has emerged as a major concern in the last fifteen years and studies on the impacts of seawater acidification on marine organisms have multiplied accordingly. This review aimed at synthesizing the literature on the effects of seawater acidification on tropical scleractinians under laboratory-controlled conditions. We identified 141 articles (published between 1999 and 2021) and separated endpoints into 22 biological categories to identify global trends for mitigation and gaps in knowledge and research priorities for future investigators. The relative number of affected endpoints increased with pH intensity (particularly for endpoints associated to calcification and reproduction). When exposed to pH 7.6-7.8 (compared to higher pH), 49% of endpoints were affected. The diversity in experimental designs prevented deciphering the modulating role of coral life stages, genera or duration of exposure. Finally, important bias in research efforts included most experiments on adult corals (68.5%), in 27 out of 150 (18%) coral ecoregions and exclusively from shallow-waters.