Posts Tagged 'fisheries'

Investigating the environmental sustainability of a seabass and seabream aquaculture system in Portugal based on life cycle and nexus approaches

Published 25 May 2023 Science Leave a Comment
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Highlights

  • A Portuguese seabass and seabream aquaculture system was analysed.
  • A climate change impact equal to 2.88 kg CO2-eq/kg MSF was found.
  • The aquaculture system depends 59 % on non-renewable resources.
  • In resource terms, 504.1 MJex are needed per kg of protein.
  • Potential strategies are given to improve environmental sustainability.

Abstract

Aquaculture plays an essential role in supplying animal-source food and protein worldwide, in this way contributing to several sustainable development goals. Notwithstanding this, the aquaculture sector’s long-term environmental sustainability is a major concern due to overall environmental impacts. To date, and to the best of the authors’ knowledge, assessments of aquaculture systems in Portugal from an environmental perspective, and the nexus between resource consumption and nutrition issues, are still lacking. This study bridges this gap by analysing an aquaculture system in Portugal in a comprehensive manner by applying and combining life cycle assessment and resources–protein nexus approaches. The overall results highlight feed as the main factor responsible for the total impact in all impact categories selected, ranging from 74 % to 98 %. Climate change impact results in 2.88 kg CO2-eq per kg of medium-size fish (functional unit). The resources–protein nexus shows that 504.1 MJex is needed to obtain 1 kg of edible protein, with a high dependency on non-renewable resources (59 %), mainly oil by-product fuels used in feed production. After identifying environmental hotspots, potential strategies to be adopted such as resource consumption reduction, eco-certification and ecosystem-based management are suggested, in this way ensuring long-term aquaculture production and environmental sustainability.

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Applications of ecosystem risk assessment in federal fisheries to advance ecosystem-based fisheries management

Published 11 May 2023 Newsletters and reports Closed
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Executive Summary

Managing U.S. federal fisheries often requires considering complex interactions among fisheries, protected species, habitats, and other ecosystem components, including humans and climate. In addition, management that focuses on individual species can experience undesirable and unexpected changes due to unaccounted for impacts of climate or other ecosystem factors. Regional fishery management councils (Councils) need ways to efficiently process these interactions and the potential impacts they may have on meeting Council management objectives. One tool that can help with this is the ecosystem-level risk assessment (ERA), also called ecological risk assessments or vulnerability assessments. ERAs are management decision tools that can assist Councils in integrating large amounts of ecosystem information in a standardized, yet flexible and transparent way to help identify issues to prioritize in science or management. The purpose of this document is to share applied results from five regional case studies of ERA. The case studies cover different geographies illustrate how Councils can systematically approach ERA to help address current challenges and advance ecosystem-based fisheries management. To demonstrate the versatility of this tool, we organized the case studies by three different applications in the adaptive fishery management process: screening, prioritization, and evaluation. We emphasized broader ERAs that analyzed a number of different ecosystem drivers in one assessment. To improve the process of incorporating ecosystem information into fishery management decisions, we summarize key takeaways from the case studies. Finally, we provide additional recommendations for optimizing ERA use at the end of this report.

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Water quality and carbonate chemistry dynamics in an estuarine system impacted by mariculture

Published 9 May 2023 Science Closed
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Cultural eutrophication due to the increasing demand of an expanding population has posed negative impacts on estuarine systems worldwide. In tropical regions, the variability in the inputs of nutrients and organic matter from rivers to coasts is further influenced by the changing monsoon seasons. This study examined the water quality and carbonate chemistry in a semi-enclosed estuary in the northwest Philippines that is used for farming milkfish and other aquaculture species. Data suggests that the mariculture area is a heterotrophic system enriched in dissolved inorganic carbon and pCO2 but depleted of nitrate due to the decomposition of unconsumed and undigested fish feeds from mariculture activities. The different river systems surrounding the estuary act as nitrate sources that could relieve nitrogen limitation during the wet season. Results also show hypoxic conditions not only in mariculture waters but in river systems as well. Accounts of the overflow of hypoxic river waters to the mariculture area could potentially provide a different mechanism of fish kill occurrence and requires further scientific observations. pH data confirm fast rates of coastal acidification in mariculture waters due to organic matter decomposition to levels that are expected to be experienced by the end of this century in open ocean conditions considering the air-sea equilibrium of increasing atmospheric CO2. These results highlight the need for more advanced biogeochemical and transdisciplinary investigations of these transition zones and their implications on climate, biodiversity, and sustainability.  

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Water quality and the CO2-carbonate system during the preconditioning of Pacific oyster (Crassostrea gigas) in a recirculating aquaculture system

Published 5 May 2023 Science Closed
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The continued increase of the demand for seed of the Pacific oyster (Crassostrea gigas) has driven the aquaculture industry to produce land-based hatcheries using broodstock conditioning. This has led to the need to create closed systems to control the main factors involved in reproduction (temperature and food). Additionally, reproductive synchronization of broodstocks may be considered to ensure homogeneous maturation and spawning among the organisms. In this work, we synchronized the broodstock reproductive stage of Pacific oysters in a recirculating aquaculture system (RAS) using a “preconditioning” process and evaluated the effect of the water quality and the CO2-carbonate system on preconditioned broodstock. The oysters were kept at 12 °C for 45 days in a RAS containing a calcium reactor (C2) or without a calcium reactor (C1, control). Water quality parameters were measured daily, and the oyster’s condition and reproductive development were monitored using condition index, biometrics, and histology, on Days 0, 20, and 45. C1 and C2 systems kept the water quality within the ranges reported as favorable for bivalves. The calcium reactor kept the pH (8.03–8.10), alkalinity (200 mg/L as CaCO3), CO32− (≤ 80 µmol/kg), and Ω aragonite (≤ 1) closer to the ranges reported as optimal for bivalves. However, no significant differences were detected in the total weight and the condition index in C1 and C2. The preconditioning allowed to maintain the organisms in early reproductive development, allowing gametogenesis synchronization to start maturation.

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Ocean acidification as a governance challenge in the Mediterranean Sea: impacts from aquaculture and fisheries

Published 25 April 2023 Science Closed
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Despite the progress in the international and regional governance efforts at the level of climate change, ocean acidification (OA) remains a global problem with profoundly negative environmental, social, and economical consequences. This requires extensive mitigation and adaptation effective strategies that are hindered by current shortcomings of governance. This multidisciplinary chapter investigates the risks of ocean acidification (OA) for aquaculture and fisheries in the Mediterranean Sea and its sub-basins and the role of regional adaptive governance to tackle the problem. The identified risks are based on the biological sensitivities of the most important aquaculture species and biogenic habitats and their exposure to the current and future predicted (2100) RCP 8.5 conditions. To link OA exposure and biological sensitivity, we produced spatially resolved and depth-related pH and aragonite saturation state exposure maps and overlaid these with the existing aquaculture industry in the coastal waters of the Mediterranean basin to demonstrate potential risk for the aquaculture in the future. We also identified fisheries’ vulnerability through the indirect effects of OA on highly sensitive biogenic habitats that serve as nursery and spawning areas, showing that some of the biogenic habitats are already affected locally under existing OA conditions and will be more severely impacted across the entire Mediterranean basin under 2100 scenarios. This provided a regional vulnerability assessment of OA hotspots, risks and gaps that created the baseline for discussing the importance of adaptive governance and recommendations for future OA mitigation/adaptation strategies. By understanding the risks under future OA scenarios and reinforcing the adaptability of the governance system at the science-policy interface, best informed, “situated” management response capability can be optimised to sustain ecosystem services.

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Aquaculture mapping in the context of climate change

Published 24 April 2023 Science Closed
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The development of aquaculture is facing unprecedented pressures from climate change, resource constraints, environmental pollution, energy consumption, and other factors. For coping with these challenges and for ensuring sustainable development of aquaculture, spatial planning in aquaculture activities become more and more important. An ecosystem-based approach for aquaculture mapping is needed to strategically and comprehensively balance the location, aquaculture type, and stakeholders’ interests. In this chapter, we aim to describe the definition, key steps, and methods of aquaculture zoning, especially in the context of climate change (e.g., global warming, ocean acidification, hypoxia/anoxia, sea level rising, and extreme events). We also provide two case studies of aquaculture mapping in China.

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Resilience of a giant clam subsistence fishery in Kiribati to climate change

Published 20 April 2023 Science Closed
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Changes in sea surface temperature have historically impacted the habitat of giant clams in Kiribati. In many islands of Kiribati, the four species of giant clam have largely withstood these environmental changes, through adaptive responses to anthropogenic pressures. The Kiribati giant clam fishery is a data-limited multi-species fishery, so in adopting and applying a comprehensive resilience framework to highlight attributes conferring and limiting resilience across the ecological, governance, and socio-economic aspects of the fishery we used knowledge co-production and the precautionary principle approach to better inform place-based attempts to operationalise resilience measures. We found that the resilience of the fishery to marine heatwaves and ocean acidification, as highlighted by local stakeholders, will depend on the ability of fisheries stakeholders to act collectively, with flexibility, to implement adaptive governance. Climate change, coupled with human impacts, have reduced ecological resilience in the urbanised island of South Tarawa, in contrast to the more remote or sparsely populated islands. In South Tarawa, governance and social processes are less flexible, leading to declines in the local subsistence clam fishery. Conversely, on several remote outer islands, where the social-ecological system has shown promise in combating these anthropogenic influences (e.g., through adaptive community-based fisheries management), the ecological resilience has improved, and the subsistence clam fishery has persisted. Our case study demonstrates the importance of a participatory approach and local knowledge when assessing climate resilience and identifies pathways of resilience in other small-scale fisheries, especially when data are limited.

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The influence of ocean acidification and warming on responses of Scylla serrata to oil pollution: an integrated biomarker approach

Published 28 March 2023 Science Closed
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Graphical abstract

Highlights

  • The OAW conditions reduce tolerance capacity of crabs to acute pollution stress.
  • A greater degree of stress was experienced in oil exposure under OAW conditions.
  • Augmented antioxidant and detoxification enzyme activity was noted.

Abstract

Anthropogenic activities primarily combustion of fossil fuel is the prime cause behind the increased concentration of CO2 into the atmosphere. As a consequence, marine environments are anticipated to experience shift towards lower pH and elevated temperatures. Moreover, since the industrial revolution the growing demand for petroleum-based products has been mounting up worldwide leading to severe oil pollution. Sundarbans estuarine system (SES) is experiencing ocean warming, acidification as well as oil pollution from the last couple of decades. Scylla serrata is one of the most commercially significant species for aquaculture in coastal areas of Sundarbans. Thus, the prime objective of this study is to delineate whether exposure under ocean warming and acidification exacerbates effect of oil spill on oxidative stress of an estuarine crab S. serrata. Animals were separately exposed under current and projected climate change scenario for 30 days. After this half animals of each treatment were exposed to oil spill conditions for 24 h. Oxidative stress status superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), lipid peroxidation (LPO level) and DNA damage (Comet assay) were measured. Augmented antioxidant and detoxification enzyme activity was noted except for SOD but failed to counteract LPO and DNA damage. The present results clearly highlighted the detrimental combined effect of OWA and pollution on oxidative stress status of crabs that might potentially reduce its population and affect the coastal aquaculture in impending years.

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Sensitivity of fishery resources to climate change in the warm-temperate Southwest Atlantic Ocean

Published 24 March 2023 Science Closed
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Climate change impacts on fishery resources have been widely reported worldwide. Nevertheless, a knowledge gap remains for the warm-temperate Southwest Atlantic Ocean—a global warming hotspot that sustains important industrial and small-scale fisheries. By combining a trait-based framework and long-term landing records, we assessed species’ sensitivity to climate change and potential changes in the distribution of important fishery resources (n = 28; i.e., bony fishes, chondrichthyans, crustaceans, and mollusks) in Southern Brazil, Uruguay, and the northern shelf of Argentina. Most species showed moderate or high sensitivity, with mollusks (e.g., sedentary bivalves and snails) being the group with the highest sensitivity, followed by chondrichthyans. Bony fishes showed low and moderate sensitivities, while crustacean sensitivities were species-specific. The stock and/or conservation status overall contributed the most to higher sensitivity. Between 1989 and 2019, species with low and moderate sensitivity dominated regional landings, regardless of the jurisdiction analyzed. A considerable fraction of these landings consisted of species scoring high or very high on an indicator for potential to change their current distribution. These results suggest that although the bulk of past landings were from relatively climate-resilient species, future catches and even entire benthic fisheries may be jeopardized because (1) some exploited species showed high or very high sensitivities and (2) the increase in the relative representation of landings in species whose distribution may change. This paper provides novel results and insights relevant for fisheries management from a region where the effects of climate change have been overlooked, and which lacks a coordinated governance system for climate-resilient fisheries.

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Ocean acidification as a governance challenge in the Mediterranean Sea: impacts from aquaculture and fisheries

Published 21 March 2023 Science Closed
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Despite the progress in the international and regional governance efforts at the level of climate change, ocean acidification (OA) remains a global problem with profoundly negative environmental, social, and economical consequences. This requires extensive mitigation and adaptation effective strategies that are hindered by current shortcomings of governance. This multidisciplinary chapter investigates the risks of ocean acidification (OA) for aquaculture and fisheries in the Mediterranean Sea and its sub-basins and the role of regional adaptive governance to tackle the problem. The identified risks are based on the biological sensitivities of the most important aquaculture species and biogenic habitats and their exposure to the current and future predicted (2100) RCP 8.5 conditions. To link OA exposure and biological sensitivity, we produced spatially resolved and depth-related pH and aragonite saturation state exposure maps and overlaid these with the existing aquaculture industry in the coastal waters of the Mediterranean basin to demonstrate potential risk for the aquaculture in the future. We also identified fisheries’ vulnerability through the indirect effects of OA on highly sensitive biogenic habitats that serve as nursery and spawning areas, showing that some of the biogenic habitats are already affected locally under existing OA conditions and will be more severely impacted across the entire Mediterranean basin under 2100 scenarios. This provided a regional vulnerability assessment of OA hotspots, risks and gaps that created the baseline for discussing the importance of adaptive governance and recommendations for future OA mitigation/adaptation strategies. By understanding the risks under future OA scenarios and reinforcing the adaptability of the governance system at the science-policy interface, best informed, “situated” management response capability can be optimised to sustain ecosystem services.

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Oceans and the changing climate

Published 8 March 2023 Science Closed
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Increasing levels of atmospheric greenhouse gases are producing changes in the world’s oceans and coastal environments, such as increasing sea surface temperatures, ocean acidification, and rising sea levels. This chapter explores the human dimensions of three climate change impacts: (1) rising sea levels, measures to adapt, and the potential displacement of persons from eroding, low-lying coastal areas; (2) the migration of fish stocks to new habitats resulting from increasing seawater temperatures; and (3) the degradation of coral reefs and impacts to shellfish resulting from ocean acidification. With sea level rise, millions of people in low-lying coastal cities and small island developing states must adapt or be displaced, and some will become climate refugees. In the case of fisheries, distributions of some fish stocks are already changing because of increasing ocean temperatures. These shifts have great implications for both fishers and managers of marine resources. Finally, rising atmospheric concentrations of CO2 that lower the ocean’s pH make it more difficult for corals and shellfish to precipitate the calcium carbonate that forms their exoskeletons and shells, affecting users of tropical coral reef ecosystems as well as the shellfish aquaculture industry.

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Oregon shellfish farmers: perceptions of stressors, adaptive strategies, and policy linkages

Published 3 February 2023 Science Closed
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Highlights

  • Interviews were conducted with fifteen (79%) of oyster farmers in Oregon.
  • Farmers are most impacted by environmental, economic, and regulatory stressors.
  • Shellfish farmers had matching adaptive strategies to address these stressors.
  • Flexible aquaculture policies can help support these strategies.

Abstract

In the United States, domestic oyster aquaculture production is insufficient to meet national demand, thus creating a reliance on international oyster imports for consumption. West coast shellfish farmers are threatened by climate change, including ocean acidification as well as socioeconomic challenges such as labor availability. To expand and enhance United States oyster production, and support domestic food security and livelihoods, a better understanding of the limitations that oyster farmers’ experience, and corresponding pathways forward for adaptation is needed. Through semi-structured interviews conducted with commercial Oregon shellfish farmers, we assess the environmental, economic, social and regulatory stressors impacting oyster growing operations, and the corresponding adaptive strategies employed or envisioned by aquaculture farmers. We find farmers are most impacted by environmental stressors (nuisance species that interact with oysters or oyster habitat negatively), followed by regulatory and economic stressors (permitting and regulations and labor availability). Farmers perceived ocean acidification as a risk, but primarily at the oyster larva stage rather than the juvenile or adult grow-out stage. Examples of farmer-identified adaptive strategies included streamlining permitting and regulations, incentivizing employee retention, and having flexibility in culture type to avoid nuisance species and other environmental stressors. An increase in targeted outreach related to aquaculture policies and engagement with industry, scientists, managers, and policy-makers could facilitate policies that support these and other adaptive strategies.

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Observed and projected impacts of coastal warming, acidification, and deoxygenation on Pacific oyster (Crassostrea gigas) farming: a case study in the Hinase Area, Okayama Prefecture and Shizugawa Bay, Miyagi Prefecture, Japan

Published 20 December 2022 Science Closed
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Coastal warming, acidification, and deoxygenation are progressing, primarily due to the increase in anthropogenic CO2. Coastal acidification has been reported to have effects that are expected to become more severe as acidification progresses, including inhibiting formation of the shells of calcifying organisms such as shellfish. However, compared to water temperature, an indicator of coastal warming, spatiotemporal variations in acidification and deoxygenation indicators such as pH, aragonite saturation state (Ωarag), and dissolved oxygen in coastal areas of Japan have not been observed and projected. Moreover, many species of shellfish are important fisheries resources, including Pacific oyster (Crassostrea gigas). Therefore, there is concern regarding the future combined impacts of coastal warming, acidification, and deoxygenation on Pacific oyster farming, necessitating evaluation of current and future impacts to facilitate mitigation measures. We deployed continuous monitoring systems for coastal warming, acidification, and deoxygenation in the Hinase area of Okayama Prefecture and Shizugawa Bay in Miyagi Prefecture, Japan. In Hinase, the Ωarag value was often lower than the critical level of acidification for Pacific oyster larvae, although no impact of acidification on larvae was identified by microscopy examination. Oyster larvae are anticipated to be affected more seriously by the combined impacts of coastal warming and acidification, with lower pH and Ωarag values and a prolonged spawning period, which may shorten the oyster shipping period and lower the quality of oysters. No significant future impact of surface-water deoxygenation on Pacific oysters was identified. To minimize the impacts of coastal warming and acidification on Pacific oyster and related local industries, cutting CO2 emissions is mandatory, but adaptation measures such as regulation of freshwater and organic matter inflow from rivers and changes in the form of oyster farming practiced locally might also be required.

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Size matters: physiological sensitivity of the scallop Argopecten purpuratus to seasonal cooling and deoxygenation upwelling-driven events

Published 20 December 2022 Science Closed
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Environment imposes physiological constraints which are life-stage specific as growth-maintenance and/or growth-reproduction energetic requirements are size and volume-dependent. The scallop Argopecten purpuratus, one of the most important bivalve species subjected to fishery and aquaculture along the Humboldt Current System, inhabits spaces affected by continuous changes in temperature, pH, oxygen, and food availability driven by remote and local oceanographic processes. Specifically, in Chile, this species is mainly cultured in central-north Chile where is permanently affected by upwelling events of dissimilar intensity and duration which generate local conditions of acidification, deoxygenation, and cooling with different magnitudes. However, to date, it remains unknown how this economic valuable resource is physiologically affected throughout its life cycle by the continuous environmental changes driven by upwelling events of different intensities and duration along the year. Here, for the first time, A. purpuratus life-stage physiological sensitivity was assessed at a seasonal scale through a year-field experiment where growth, calcification, and survivorship were evaluated. Our study shows how seasonal differences in the upwelling phenology (here measured as changes in temperature, dissolved oxygen, pH, and primary productivity, but also as the number, duration, and intensity of cooling and de-oxygenation events) notably impacted the A. purpuratus physiological performance from juvenile to adult life-stages. This was especially noticeable during the spring season which showed the most intense cooling and deoxygenation events driven by stronger favorable-upwelling winds and the lowest growth and gross calcification rates (the highest decalcification rates) where adult stages showed the lowest performance. On the other hand, A. purpuratus survivorship was not significantly affected by upwelling intensity which would be providing evidence of the high physiological flexibility and well-locally adapted is this species to fluctuating and occasional stressful environmental conditions. Our results are significantly relevant in the climate change context as some upwelling systems are at risk to change shortly (i.e., an upwelling intensification in frequency and intensity) as a consequence of changes in the atmospheric pressures that modulate favourable-upwelling winds. These changes may certainly increase the climate related-risks of the entire socio-ecological systems related to the fishery and aquaculture of A. purpuratus along the Humboldt Current System.

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Differential gene expression analysis in the scallop Argopecten purpuratus exposed to altered pH and temperature conditions in an upwelling-influenced farming area

Published 13 December 2022 Science Closed
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Graphical abstract

Increased carbon dioxide in the atmosphere and its absorption across the ocean surface will alter natural variations in pH and temperature levels, occurring in coastal upwelling ecosystems. The scallop Argopecten purpuratus, one of the most economically important species farmed in northern Chile, has been shown to be vulnerable to these environmental drivers. However, the regulatory responses at the gene-level of scallops to these climate stressors remain almost unknown. Consequently, we used an orthogonal experimental design and RNAseq approach to analyze the acute effects of variability in pH and temperature on gene expression in the muscle tissue of A. purpuratus. In respect to control conditions (pH ~ 8.0/ 14 °C), the influence of low pH (~ 7.7) and temperature (14 °C) induced the activation of several genes associated with apoptotic signaling pathways and protein localization to plasma membrane. Elevated temperature (18 °C) and pH (~8.0) conditions increased the expression of transcripts associated with the activation of muscle contraction, regulation, and sarcomere organization effects on muscle tissue. In scallops exposed to low pH and elevated temperature, the genes expressed were differentially associated with the oxidation-reduction process, signal translation, and positive regulation of GTPase activity. These results indicated that the differentially expressed genes under the experimental conditions tested are mainly related to the mitigation of cellular damage and homeostasis control. Our results add knowledge about the function of the adductor muscle in response to stressors in scallops. Furthermore, these results could help in the identification of molecular biomarkers of stress necessary to be integrated into the aquaculture programs for the mitigation of climate change.

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Promoting pinto abalone (Haliotis kamtschatkana) recovery in the Salish Sea: the effects of fluctuating temperature and elevated CO2 on survival, growth, and radula morphology

Published 12 December 2022 Science Closed
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Overharvesting of pinto abalone (Haliotis kamtschatkana) in the Salish Sea between 1959 and 1994 caused severe population declines. This led to the Washington Department of Fish and Wildlife classifying pinto abalone as a “species of concern.” The Puget Sound Restoration Fund (PSRF) is committed to help pinto abalone recover by outplanting juveniles at specific sites around the Salish Sea. Survival of outplanted individuals is different at each site, but it is not clear why. Differences in water chemistry parameters, such as temperature and pH, could explain the differences in survival, either through differences in the mean conditions or through short term exposure to more extreme conditions. Future ocean warming and acidification could make fluctuations in water chemistry parameters more severe. The goal of my thesis was to simulate in lab the outplanting of abalone post-sets in fluctuating temperature and elevated CO2 conditions. I utilized an ocean acidification system to create atmospheres that affect seawater pH. I hypothesized that temperature fluctuations and high dissolved CO2 (low pH) will negatively affect survival, growth, and shell and radula morphology. Fluctuating temperatures yielded lower survival and greater growth, determined by mean shell length, compared to constant temperature. High CO2 yielded comparable survival and smaller growth than low CO2. Traditional morphological analysis of the radula found that fluctuating temperatures caused the radula to grow in a more compact manner, with smaller teeth formed closer together. Geometric morphological analysis found that radula tooth orientation was not affected by any of the treatments. This is the first study to find any effects of water chemistry on abalone radula morphology. Overall, the presence of a single stressor was detrimental to pinto abalone post-sets. However, the combination of stressors performed similarly to the absence of stressors. This indicates that fluctuating temperature can mitigate the negative effects of high CO2, possibly by increasing metabolic rate. In support of pinto abalone recovery efforts, PSRF can utilize my findings to evaluate water chemistry parameters at their outplant sites. I recommend that pinto abalone be outplanted in areas around the Salish Sea that are characterized by near constant temperatures, around 10°C, and low dissolved CO2 (high pH around 8.2). Due to yearly, seasonal, and weekly changes in water chemistry conditions, constant conditions do not exist. Outplant sites with the smallest fluctuations in water chemistry parameters should be used. In addition, ocean warming and acidification are expected to occur in concert. My findings indicate pinto abalone post-sets should be able to survive and grow under future climate scenarios, when outplanted into both temperatures that fluctuate on weekly scales, from 10°C up to 14°C, and acidification within 0.2 pH units when these conditions occur together, not separately.

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Global climate change risk to fisheries – a multi-risk assessment

Published 8 December 2022 Science Closed
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Our study explores variations in the risk of fishery-dependent coastal nations to ocean acidification, sea surface temperature change, sea level rise, and storms. Our findings reveal differences in risk based on geographical location and the development status of a country. Our findings indicate significant geographical differences for three of the four risk indicators including sea level rise, sea surface temperature changes, and storms. Strategies for reducing risk globally thus need to be adapted to regional differences in risks. We further detected multiple inter-regional differences, indicating that risk was not uniformly distributed within geographic regions suggesting that some regions could see an increase in conflicts over fish resources due to uneven impacts of climate change on fisheries. In addition, we found that a number of countries are at medium to very high risk to multiple climate-related impacts, indicating the need for strategies that increase adaptive capacity in general in these countries to cope with any kind of impact in addition to specific risk reduction strategies. We also found that overall small island developing states were most at risk. Yet, further analysis showed that grouping of countries in pre-defined groups fails to detect variations in risk among countries within these groups. More specific national indicators provide more nuanced insights into risk patterns.

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Transcriptome analysis of hepatopancreas in penaeus monodon under acute low pH stress

Published 1 December 2022 Science Closed
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The decrease of seawater pH can affect the metabolism, acid-base balance, immune response and immunoprotease activity of aquatic animals, leading to aquatic animal stress, impairing the immune system of aquatic animals and weakening disease resistance, etc. In this study, we performed high-throughput sequencing analysis of the hepatopancreas transcriptome library of low pH stress penaeus monodon, and after sequencing quality control, a total of 43488612–56271828 Clean Reads were obtained, and GO annotation and KEGG pathway enrichment analysis were performed on the obtained Clean Reads, and a total of 395 DEGs were identified. we mined 10 differentially expressed and found that they were significantly enriched in the Metabolic pathways (ko01100), Biosynthesis of secondary metabolites (ko01110), Nitrogen metabolism (ko00910) pathways, such as PIGA, DGAT1, DGAT2, UBE2E on Metabolic pathways; UGT, GLT1, TIM genes on Biosynthesis of secondary metabolites; CA, CA2, CA4 genes on Nitrogen metabolism, are involved in lipid metabolism, induction of oxidative stress and inflammation in the muscular body of spot prawns. These genes play an important role in lipid metabolism, induction of oxidative stress and inflammatory response in the muscle of the shrimp. In summary, these genes provide valuable reference information for future breeding of low pH-tolerant shrimp.

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Sea surface carbonate dynamics at reefs of Bolinao, Philippines: seasonal variation and fish mariculture-induced forcing

Published 18 November 2022 Science Closed
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Coral reefs are vulnerable to global ocean acidification (OA) and local human activities will continue to exacerbate coastal OA. In Bolinao, Philippines, intense unregulated fish mariculture has resulted in regional eutrophication. In order to examine the coastal acidification associated with this activity and the impact on nearby coral reefs, water quality and carbonate chemistry parameters were measured at three reef sites, a mariculture site and an offshore, minimally impacted control site during both the wet and dry season. Additionally, benthic community composition was characterized at reef sites, and both autonomous carbonate chemistry sampling and high-frequency pH measurements were used to characterize fine-scale (diel) temporal variability. Water quality was found to be poorer at all reefs during the wet season, when there was stronger outflow of waters from the mariculture area. Carbonate chemistry parameters differed significantly across the reef flat and between seasons, with more acidic conditions occurring during the dry season and increased primary production suppressing further acidification during the wet season. Significant relationships of both total alkalinity (TA) and dissolved inorganic carbon (DIC) with salinity across all stations may imply outflow of acidified water originating from the mariculture area where pH values as low as 7.78 were measured. This apparent mariculture-induced coastal acidification was likely due to organic matter respiration as sustained mariculture will continue to deliver organic matter. While TA-DIC vector diagrams indicate greater contribution of net primary production, net calcification potential in the nearest reef to mariculture area may already be diminished. The two farther reefs, characterized by higher coral cover, indicates healthier ecosystem functioning. Here we show that unregulated fish mariculture activities can lead to localized acidification and impact reef health. As these conditions at times approximate those projected to occur globally due to OA, our results may provide insight into reef persistence potential worldwide. These results also underscore the importance of coastal acidification and indicate that actions taken to mitigate OA on coral reefs should address not only global CO2 emissions but also local perturbations, in this case fish mariculture-induced eutrophication.

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Impacts of seawater pH buffering on the larval microbiome and carry-over effects on later-life disease susceptibility in Pacific oysters

Published 11 November 2022 Science Closed
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Ocean acidification upwelling events and the resulting lowered aragonite saturation state of seawater have been linked to high mortality of marine bivalve larvae in hatcheries. Major oyster seed producers along North America’s west coast have mitigated impacts via seawater pH buffering (e.g., addition of soda ash). However, little consideration has been given to whether such practice may impact the larval microbiome, with potential carry-over effects on immune competency and disease susceptibility in later-life stages. To investigate possible impacts, Pacific oysters (Crassostrea gigas) were reared under soda ash pH buffered or ambient pH seawater conditions for the first 24 h of development. Both treatment groups were then reared under ambient pH conditions for the remainder of the developmental period. Larval microbiome, immune status (via gene expression), growth, and survival were assessed throughout the developmental period. Juveniles and adults arising from the larval run were then subjected to laboratory-based disease challenges to investigate carry-over effects. Larvae reared under buffered conditions showed an altered microbiome, which was still evident in juvenile animals. Moreover, reduced survival was observed in both juveniles and adults of the buffered group under a simulated marine heatwave and Vibrio exposure compared with those reared under ambient conditions. Results suggest that soda ash pH buffering during early development may compromise later-life stages under stressor conditions, and illustrate the importance of a long-view approach with regard to hatchery husbandry practices and climate change mitigation.

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