Posts Tagged 'mitigation'

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

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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Assessing the future carbon budget through the lens of policy-driven acidification and temperature targets

Basing a future carbon budget on warming targets is subject to uncertainty due to uncertainty in the relationship between carbon emissions and warming, and may not prevent dangerous change throughout the entire climate system. Here, we use a climate emulator to constrain a future carbon budget that is more representative by using a combination of both warming and ocean acidification targets. The warming targets considered are the Paris Agreement targets of 1.5 and 2°C; the acidification targets are -0.17 and -0.21 pH units informed by aragonite saturation states. Considering acidification targets in conjunction with warming targets is found to narrow the uncertainty in the future carbon budget, especially in situations where the acidification target is more stringent than, or of similar stringency to, the warming target. Considering a strict combination of the two more stringent targets (both targets of 1.5°C warming and -0.17 acidification must be met), the carbon budget ranges from -74.0 to 129.8PgC. This reduces uncertainty in the carbon budget from 286.2PgC to 203.8PgC (29%). Assuming an emissions rate held constant since 2021 (which is a conservative assumption), the budget towards both targets was either spent by 2019, or will be spent by 2026.

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Coral reef fishes in a multi-stressor world

Coral reef fishes and the ecosystems they support represent some of the most biodiverse and productive ecosystems on the planet yet are under threat as they face dramatic increases in multiple, interacting stressors that are largely intensified by anthropogenic influences, such as climate change. Coral reef fishes have been the topic of 875 studies between 1979 and 2020 examining physiological responses to various abiotic and biotic stressors. Here, we highlight the current state of knowledge regarding coral reef fishes’ responses to eight key abiotic stressors (i.e., pollutants, temperature, hypoxia and ocean deoxygenation, pH/CO2, noise, salinity, pressure/depth, and turbidity) and four key biotic stressors (i.e., prey abundance, predator threats, parasites, and disease) and discuss stressors that have been examined in combination. We conclude with a horizon scan to discuss acclimation and adaptation, technological advances, knowledge gaps, and the future of physiological research on coral reef fishes. As we proceed through this new epoch, the Anthropocene, it is critical that the scientific and general communities work to recognize the issues that various habitats and ecosystems, such as coral reefs and the fishes that depend on and support them, are facing so that mitigation strategies can be implemented to protect biodiversity and ecosystem health.

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Seaweeds cultivation methods and their role in climate mitigation and environmental cleanup

Seaweed cultivation is an emerging sector of food production that can full fill the future food demand of the growing population. Considering the importance, Asia is home to seven of the top ten seaweed-producing nations, and Asian countries contributed 99.1% of all seaweed cultivated for food. Besides, it can reduce the carbon budget of the ocean through seaweed farms and act as a CO2 sink. In the context of climate change mitigation, the seaweed culture is the energy crop, and during its entire life cycle can serve as a bio-filter and bio-extractor. The climate change effect can be reduced by farming seaweed on a commercial scale and it will protect the coastal area by decreasing the physical damage through damping wave energy. The seaweed can reduce eutrophication by removing excess nutrients from water bodies and releasing oxygen as a byproduct in return. The cultivation of seaweed plays an important role as the source of bioenergy for full fill the future energy requirement and it will act as clean energy through the establishment of algal biorefinery along with the seaweed cultivation site. Thus, the marine energy industrial sector moves further toward large-scale expansion of this sector by adopting energy devices to offer power for seaweed growth for biofuel operation. The current reviews provides the evidence of seaweed farming methodology adopted by different countries, as well as their production and output. To mitigate climate change by direct measures such as carbon sequestration, eutrophication risk reduction, and bioenergy, as well as through indirect measures like supplying food for cattle and reducing the strain on aquaculture. The US, Japan, and Germany lastly suggest the large-scale offshore commercial farming as a feasible climate change mitigation strategy.

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Seaweed farming for food and nutritional security, climate change mitigation and adaptation, and women empowerment: a review

Seaweed is a promising marine macroalgae of the millennium, providing various ecological, social, and economic benefits. At present, seaweed production reached 35.8 million t from farming, accounting for 97% of global seaweed output, with a world market of US$ 11.8 billion. Seaweeds are an excellent source of nutritious human food because of their low lipid content, high minerals, fibers, polyunsaturated fatty acids, polysaccharides, vitamins, and bioactive compounds. Many seaweed sub-products offer unique properties to develop various functional foods for the food processing industries. In the perspective of climate change mitigation, seaweed farms absorb carbon, serve as a CO2 sink and reduce agricultural emissions by providing raw materials for biofuel production and livestock feed. Seaweed farming system also helps in climate change adaptation by absorbing wave energy, safeguarding shorelines, raising the pH of the surrounding water, and oxygenating the waters to minimize the impacts of ocean acidification and hypoxia on a localized scale. Moreover, it contributes substantially to the sustainable development of the economic condition of coastal women by providing livelihood opportunities and ensuring financial solvency. This review paper highlights the significance of seaweed farming in global food and nutritional security, mitigation and adaptation to global climate change, and women empowerment within a single frame. This review paper also outlined the major issues and challenges of seaweed farming for obtaining maximum benefits in these aspects. The main challenges of making seaweed as a staple diet to millions of people include producing suitable species of seaweeds, making seaweed products accessible, affordable, nutritionally balanced, and attractive to the consumers. Various food products must be developed from seaweeds that may be considered equivalent to the foods consumed by humans today. Lack of effective marine spatial planning to avoid user conflicts is vital for expanding the seaweed farming systems to provide aquatic foods and contribute globally for mitigation and adaptation of climate change impacts. Hence, women’s empowerment through seaweed farming is primarily constrained by the lack of technical knowledge and financial resources to establish the coastal farming system. All the information discussed in this paper will help to understand the critical needs for large-scale seaweed farming for climate resilience mariculture, potentials for global food security, and future research on various aspects of seaweed farming and their diverse utilization.

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Harvesting, storing, and converting carbon from the ocean to create a new carbon economy: challenges and opportunities

Ever-increasing anthropogenic CO2 emissions have required us to develop carbon capture, utilization, and storage (CCUS) technologies, and in order to address climate change, these options should be at scale. In addition to engineered systems of CO2 capture from power plants and chemical processes, there are emerging approaches that include the Earth (i.e., air, Earth, and ocean) within its system boundary. Since oceans constitute the largest natural sink of CO2, technologies that can enhance carbon storage in the ocean are highly desired. Here, we discuss alkalinity enhancement and biologically inspired CO2 hydration reactions that can shift the equilibrium of ocean water to pump more carbon into this natural sink. Further, we highlight recent work that can harvest and convert CO2 captured by the ocean into chemicals, fuels, and materials using renewable energy such as off-shore wind. Through these emerging and innovative technologies, organic and inorganic carbon from ocean-based solutions can replace fossil-derived carbon and create a new carbon economy. It is critical to develop these ocean-based CCUS technologies without unintended environmental or ecological consequences, which will create a new engineered carbon cycle that is in harmony with the Earth’s system.

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Vulnerability of exploited deep-sea demersal species to ocean warming, deoxygenation, and acidification

Vulnerability of marine species to climate change (including ocean acidification, deoxygenation, and associated changes in food supply) depends on species’ ecological and biological characteristics. Most existing assessments focus on coastal species but systematic analysis of climate vulnerability for the deep sea is lacking. Here, we combine a fuzzy logic expert system with species biogeographical data to assess the risks of climate impacts to the population viability of 32 species of exploited demersal deep-sea species across the global ocean. Climatic hazards are projected to emerge from historical variabilities in all the recorded habitats of the studied species by the mid-twenty-first century. Species that are both at very high risk of climate impacts and highly vulnerable to fishing include Antarctic toothfish (Dissostichus mawsoni), rose fish (Sebastes norvegicus), roughhead grenadier (Macrourus berglax), Baird’s slickhead (Alepocephalus bairdii), cusk (Brosme brosme), and Portuguese dogfish (Centroscymnus coelepis). Most exploited deep-sea fishes are likely to be at higher risk of local, or even global, extinction than previously assessed because of their high vulnerability to both climate change and fishing. Spatially, a high concentration of deep-sea species that are climate vulnerable is predicted in the northern Atlantic Ocean and the Indo-Pacific region. Aligning carbon mitigation with improved fisheries management offers opportunities for overall risk reduction in the coming decades. Regional fisheries management organizations (RFMOs) have an obligation to incorporate climate change in their deliberations. In addition, deep-sea areas that are not currently managed by RFMOs should be included in existing or new international governance institutions or arrangements.

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Marine pelagic ecosystem responses to climate variability and change

The marine coastal region makes up just 10% of the total area of the global ocean but contributes nearly 20% of its total primary production and over 80% of fisheries landings. Unicellular phytoplankton dominate primary production. Climate variability has had impacts on various marine ecosystems, but most sites are just approaching the age at which ecological responses to longer term, unidirectional climate trends might be distinguished. All five marine pelagic sites in the US Long Term Ecological Research (LTER) network are experiencing warming trends in surface air temperature. The marine physical system is responding at all sites with increasing mixed layer temperatures and decreasing depth and with declining sea ice cover at the two polar sites. Their ecological responses are more varied. Some sites show multiple population or ecosystem changes, whereas, at others, changes have not been detected, either because more time is needed or because they are not being measured.

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Stability of coral reef islands and associated legal maritime zones in a changing ocean

Coral reef islands can support large legal maritime zones (i.e., ocean spaces where States have rights and responsibilities) and are of international and geopolitical importance. This review focuses on low-lying coral reef islands supplied with sediments derived from skeletons and shells of calcifying organisms. For coral islands, the outer ‘low-water line’ of the reef can be used as the legal ‘baseline’ to establish maritime zones. Coral islands and the reefs that support them are experiencing the effects of rising and warming seas, increased storminess and ocean acidification. Coral reefs, their islands and associated maritime zones support millions of people, including those in Small Island Developing States (SIDS). SIDS communities are arguably the least responsible for climate change but are at the forefront of its impacts so ensuring their continued wellbeing is a global responsibility. Securing the future of coral reefs and islands is dependent on reducing global climate threats and emissions, improving local management, and investing in restoration and adaption research. It is uncertain if coral islands will persist into the future, and on what timelines. This raises questions such as, where coral islands support maritime zones, what are the legal implications of island instability or loss? This review focuses on the bio-physical interactions of coral islands and associated reefs in the face of changing climates, and implications for legal maritime zones and SIDS.

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Using biomimicry and bibliometric mapping to guide design and production of artificial coral reefs

Highlights

  • We created an artificial coral reef based on biomimicry using a bibliometric method.
  • We designed stage-gates to lead the innovation process.
  • Local community and government agencies were included in the conceptualization.
  • We demonstrate the recovery in natural marine ecosystems using 3D printed coral reefs.

Abstract

Worldwide, artificial reefs are being installed to simultaneously attract recreational divers and protect deteriorating natural reefs. This study uses a bibliometric review of artificial coral reefs to identify five clusters as gate criteria for artificial reef design. These clusters enable the conceptualization and testing of artificial reefs for optimum integration of sociotechnical requirements, biological integrity, and ecological marine health. The five clusters are: (1) applications, solutions, and performance; (2) management, technology, and science; (3) calcification, biomineralization, chemistry, and ocean acidification; (4) coral species survival, mortality, and photosynthesis; and (5) artificial reef development, and coral and fish recruitment. The six biomimicry design stages are: definebiologizediscoverabstractemulate, and evaluate. The 3D printing and hard corals design attracted a large number of planula larvae and different inhabitant corals, and a high species diversity in the surrounding waters. Practical implications include biomimicry-based means for coral reef restoration and recreational ecosystem services.

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Role of abiotic factors in enhancing the capacity of mangroves in reducing ocean acidification

The present study investigated the effects of rising carbon dioxide levels in nature and the carbon sequestration potential of dominant mangrove species for reducing the toxic effects of ocean acidification. The study was conducted on the east coast of Odisha, in the western Bay of Bengal. To determine the effect of these ambient parameters on the absorption of carbon dioxide by the mangroves, water temperature, salinity, pH levels of seawater along with soil texture and pH, salinity expressed in electrical conductivity, compactness expressed in bulk density, and soil organic carbon were simultaneously monitored. The aboveground biomass and carbon of the selected species were studied for 2 consecutive years at 10 designated stations. The total carbon calculated for the study area varied from 242.50 ± 49.00 to 1321.29 ± 445.52 tons with a mean of 626.68 ± 174.81 tons for Bhitarkanika and Mahanadi mangrove chunks. This is equivalent to 2299.92 ± 641.55 tons of CO2 absorbed from the atmosphere. A total of 27 equations were selected as the best fit models for the study area. The equations between mangrove biomass and carbon along with aquatic and edaphic factors governing the pH of water and soil strongly support the positive influence of mangrove photosynthetic activity in shifting the equilibrium toward alkalinity. This calls for conservation of mangrove ecosystem to minimize the pace of acidification of estuarine water. The results indicate that Excoecariaagallocha and Avicennia marina as are the most capable species for combatting maximum carbon dioxide toxicity from the atmosphere; which will be helpful in REDD + programs and carbon-based payments for ecosystem services (PES).

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Limits and CO2 equilibration of near-coast alkalinity enhancement

Ocean Alkalinity Enhancement (OAE) has recently gained attention as a potential method for negative emissions at gigatonne scale, with near-coast OAE operations being economically favorable due to proximity to mineral and energy sources. In this paper we study critical questions which determine the scale and viability of OAE: Which coastal locations are able to sustain a large flux of alkalinity at minimal pH and ΩArag (aragonite saturation) changes? What is the interference distance between adjacent OAE projects? How much CO2 is absorbed per unit of alkalinity added? How quickly does the induced CO2 deficiency equilibrate with the atmosphere?

Using the LLC270 (0.3deg) ECCO global circulation model we find that the steady-state OAE rate varies over 1–2 orders of magnitude between different coasts and exhibits complex patterns and non-local dependencies which vary from region to region. In general, OAE in areas of strong coastal currents allow the largest fluxes and depending on the direction of coastal currents, neighboring OAE sites can exhibit dependencies as far as 400 km or more. We found that within relatively conservative constraints set on ∆pH or ∆Omega, most regional stretches of coastline are able to accommodate on the order of tens to hundreds of megatonnes of negative emissions within 300 km of the coast. We conclude that near-coastal OAE has the potential to scale globally to several GtCO2/yr of drawdown with conservative pH constraints, if the effort is spread over the majority of available coastlines.

Depending on the location, we find a diverse set of equilibration kinetics, determined by the interplay of gas exchange and surface residence time. Most locations reach an uptake-efficiency plateau of 0.6–0.8mol CO2 per mol of alkalinity after 3–4 years, after which there is little further CO2 uptake. The most ideal locations, reaching an uptake of around 0.8 include north Madagascar, San Francisco, Brazil, Peru and locations close to the southern ocean such as Tasmania, Kerguelen and Patagonia, where the gas exchange appears to occur faster than the surface residence time. Some locations (e.g. Hawaii) take significantly longer to equilibrate (up to 8–10 years), though can still eventually achieve high uptake. If the alkalinity released advects into regions of significant downwelling (e.g. around Iceland) up to half of the OAE potential can be lost to bottom waters.

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The changing ocean carbon sink in the earth system

Eunice Foote, who was the first to measure the solar heating of CO2 in her early experiments already in the 1850s noted: “An atmosphere of that gas would give to our Earth a high temperature“ (Foote, 1856). Indeed, our planet is warming unprecedently fast due to rising anthropogenic CO2 emissions (Masson-Delmotte et al., 2021). Next to catastrophic floodings, wildfires and droughts on land, with tragic consequences for people, the ocean silently suffers from the ongoing heating, acidification, and deoxygenation with tragic impacts for marine systems.

The ocean plays an essential role in regulating Earth’s climate; it is also essential for regulating the Earth’s carbon cycle. The ocean contains around 38,000 Gt of carbon. This is 16 times more than the terrestrial biosphere (plant and the underlying soils), and about 60 times more than the pre-industrial atmosphere (Canadell et al., 2021). Therefore, even a small perturbation to the ocean carbon content by changing its capacity to store carbon would impact atmospheric CO2 concentrations (Fig.1.1), making the ocean carbon sink a major regulator of the Earth’s climate on a time scale of hundreds to thousands of years. As the ocean currently continuously absorbs anthropogenic carbon from the atmosphere, it thereby has a key role in moderating ongoing climate change.

Based on the Global Carbon Budget (GCB) estimates (Friedlingstein et al., 2020), the global ocean has already taken up about one third of the cumulative anthropogenic CO2 emissions (Fig.1.2). The strength of the ocean carbon sink is determined by chemical reactions in seawater (carbonate system), biological processes (photosynthesis, export flux, and remineralization by aerobic and anaerobic respiration), and physical processes (including ocean circulation and vertical mixing). But even though these key mechanisms are identified (Landschutzer et al., 2021), there are considerable uncertainties regarding their interannual and decadal variations, as well as their susceptibility to ongoing climate change. Here, a major uncertainty arises from the lack of knowledge regarding the contribution of the natural variability of the climate system (Ilyina, 2016).

In this essay, I present my research contributions based on my papers explicitly mentioned in the text. My research was guided by the following questions:

  1. How do ocean biogeochemical cycles accommodate perturbations brought about by anthropogenic activities or natural forcings?
  2. What are the predictability horizons of variations in the ocean carbon sink?
  3. What is the potential of the ocean carbon sink, artificially enhanced by ocean alkalinity additions, to mitigate climate change?

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Microbial ecosystem responses to alkalinity enhancement in the North Atlantic subtropical gyre

In addition to reducing carbon dioxide (CO2) emissions, actively removing CO2 from the atmosphere is widely considered necessary to keep global warming well below 2°C. Ocean Alkalinity Enhancement (OAE) describes a suite of such CO2 removal processes that all involve enhancing the buffering capacity of seawater. In theory, OAE both stores carbon and offsets ocean acidification. In practice, the response of the marine biogeochemical system to OAE must be demonstrably negligible, or at least manageable, before it can be deployed at scale. We tested the OAE response of two natural seawater mixed layer microbial communities in the North Atlantic Subtropical Gyre, one at the Western gyre boundary, and one in the middle of the gyre. We conducted 4-day microcosm incubation experiments at sea, spiked with three increasing amounts of alkaline sodium salts and a 13C-bicarbonate tracer at constant pCO2. We then measured a suite of dissolved and particulate parameters to constrain the chemical and biological response to these additions. Microbial communities demonstrated occasionally measurable, but mostly negligible, responses to alkalinity enhancement. Neither site showed a significant increase in biologically produced CaCO3, even at extreme alkalinity loadings of +2,000 μmol kg−1. At the gyre boundary, alkalinity enhancement did not significantly impact net primary production rates. In contrast, net primary production in the central gyre decreased by ~30% in response to alkalinity enhancement. The central gyre incubations demonstrated a shift toward smaller particle size classes, suggesting that OAE may impact community composition and/or aggregation/disaggregation processes. In terms of chemical effects, we identify equilibration of seawater pCO2, inorganic CaCO3 precipitation, and immediate effects during mixing of alkaline solutions with seawater, as important considerations for developing experimental OAE methodologies, and for practical OAE deployment. These initial results underscore the importance of performing more studies of OAE in diverse marine environments, and the need to investigate the coupling between OAE, inorganic processes, and microbial community composition.

Continue reading ‘Microbial ecosystem responses to alkalinity enhancement in the North Atlantic subtropical gyre’

Limits and CO2 equilibration of near-coast alkalinity enhancement

Ocean Alkalinity Enhancement (OAE) has recently gained attention as a potential method for negative emissions at gigatonne scale, with near-coast OAE operations being economically favorable due to proximity to mineral and energy sources. In this paper we study critical questions which determine the scale and viability of OAE: Which coastal locations are able to sustain a large flux of alkalinity at minimal pH and ΩArag (aragonite saturation) changes? What is the interference distance between adjacent OAE projects? How much CO2 is absorbed per unit of alkalinity added? How quickly does the induced CO2 deficiency equilibrate with the atmosphere?

Using the LLC270 (0.3deg) ECCO global circulation model we find that the steady-state OAE rate varies over 1–2 orders of magnitude between different coasts and exhibits complex patterns and non-local dependencies which vary from region to region. In general, OAE in areas of strong coastal currents allow the largest fluxes and depending on the direction of coastal currents, neighboring OAE sites can exhibit dependencies as far as 400 km or more. We found that within relatively conservative constraints set on ∆pH or ∆Omega, most regional stretches of coastline are able to accommodate on the order of tens to hundreds of megatonnes of negative emissions within 300 km of the coast. We conclude that near-coastal OAE has the potential to scale globally to several GtCO2/yr of drawdown with conservative pH constraints, if the effort is spread over the majority of available coastlines.

Depending on the location, we find a diverse set of equilibration kinetics, determined by the interplay of gas exchange and surface residence time. Most locations reach an uptake-efficiency plateau of 0.6–0.8mol CO2 per mol of alkalinity after 3–4 years, after which there is little further CO2 uptake. The most ideal locations, reaching an uptake of around 0.8 include north Madagascar, San Francisco, Brazil, Peru and locations close to the southern ocean such as Tasmania, Kerguelen and Patagonia, where the gas exchange appears to occur faster than the surface residence time. Some locations (e.g. Hawaii) take significantly longer to equilibrate (up to 8–10 years), though can still eventually achieve high uptake. If the alkalinity released advects into regions of significant downwelling (e.g. around Iceland) up to half of the OAE potential can be lost to bottom waters.

Continue reading ‘Limits and CO2 equilibration of near-coast alkalinity enhancement’

Air exposure moderates ocean acidification effects during embryonic development of intertidally spawning fish

Ocean acidification can negatively impact the early life-stages of marine fish, due to energetic costs incurred by the maintenance of acid–base homeostasis, leaving less energy available for growth and development. The embryos of intertidally spawning fishes, such as Pacific herring, are often air exposed for hours. We hypothesized that air exposure would be beneficial to the developing embryo due to a higher oxygen availability (and thus reduced metabolic costs to secure adequate oxygen) and permitting excess CO2 associated with ocean acidification to be off-gassed during emersion. To investigate this, we reared Pacific herring (Clupea pallasii) embryos under three tidal regimes (subtidal: fully immersed, low intertidal: 2 × 2 h air exposure, and high intertidal: 5 + 9 h air exposure) fully crossed with three aquatic CO2 levels (400, 1500 and 3200 µatm) at a water temperature of 9.5 °C and naturally fluctuating air temperature during air exposure. We measured the effects on embryonic development and hatch, as well as carry-over effects on larval development and survival. Air exposure during embryonic development had significant positive effects on growth, condition and survival in larval Pacific herring, with some interactive effects with CO2. Interestingly, CO2 by itself in the fully immersed treatment had no effect, but had significant interactions with air exposure. Our research suggests that air exposure during low tide can be highly beneficial to intertidally spawning fishes and needs to be taken into account in climate change studies and modeling.

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A global horizon scan of issues impacting marine and coastal biodiversity conservation

The biodiversity of marine and coastal habitats is experiencing unprecedented change. While there are well-known drivers of these changes, such as overexploitation, climate change and pollution, there are also relatively unknown emerging issues that are poorly understood or recognized that have potentially positive or negative impacts on marine and coastal ecosystems. In this inaugural Marine and Coastal Horizon Scan, we brought together 30 scientists, policymakers and practitioners with transdisciplinary expertise in marine and coastal systems to identify new issues that are likely to have a significant impact on the functioning and conservation of marine and coastal biodiversity over the next 5–10 years. Based on a modified Delphi voting process, the final 15 issues presented were distilled from a list of 75 submitted by participants at the start of the process. These issues are grouped into three categories: ecosystem impacts, for example the impact of wildfires and the effect of poleward migration on equatorial biodiversity; resource exploitation, including an increase in the trade of fish swim bladders and increased exploitation of marine collagens; and new technologies, such as soft robotics and new biodegradable products. Our early identification of these issues and their potential impacts on marine and coastal biodiversity will support scientists, conservationists, resource managers and policymakers to address the challenges facing marine ecosystems.

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Integrated multi-trophic aquaculture mitigates the effects of ocean acidification: seaweeds raise system pH and improve growth of juvenile abalone

Highlights

  • Integrated multi-trophic aquaculture (IMTA) with seaweeds improves abalone growth.
  • IMTA designs with high recirculation rates increase system pH.
  • Abalone growth was positively associated with pH levels in the IMTA system.
  • IMTA designs altered water chemistry and can reduce eutrophication.
  • IMTA designs can reduce the time to market for abalone from 4 to 3 years.

Abstract

Integrated multi-trophic aquaculture (IMTA) has the potential to enhance growth, reduce nutrient loads, and mitigate environmental conditions compared to traditional single-species culture techniques. The goal of this project was to develop a land-based system for the integrated culture of seaweeds and shellfish, to test the efficacy of integrated versus non-integrated designs, and to assess the potential for IMTA to mitigate the effects of climate change from ocean acidification on shellfish growth and physiology. We utilized the red abalone (Haliotis rufescens) and the red seaweed dulse (Devaleraea mollis) as our study species and designed integrated tanks at three different recirculation rates (0%, 30%, and 65% recirculation per hour) to test how an integrated design would affect growth rates of the abalone and seaweeds, modify nutrient levels, and change water chemistry. We specifically hypothesized that IMTA designs would raise seawater pH to benefit calcifying species. Our results indicated that juvenile abalone grew significantly faster in weight (22% increase) and shell area (11% increase) in 6 months in tanks with the highest recirculation rates (65%). The 65% recirculation treatment also exhibited a significant increase in mean seawater pH (0.2 pH units higher) due to the biological activity of the seaweed in the connected tanks. We found a significant positive relationship between the mean pH of seawater in the tanks and juvenile abalone growth rates across all treatments. There were no significant differences in the growth of dulse among treatments, but dulse growth did vary seasonally. Seawater phosphate and nitrate concentrations were depleted in the highest recirculation rate treatment, but ammonium concentrations were elevated, likely due to the abalone effluent. Overall, our results indicate that there are benefits to IMTA culture of seaweeds and abalone in terms of improving growth in land-based systems, which will reduce the time to market and buffer commercial abalone operations against the effects of ocean acidification during vulnerable early life stages.

Continue reading ‘Integrated multi-trophic aquaculture mitigates the effects of ocean acidification: seaweeds raise system pH and improve growth of juvenile abalone’

Sustainable development of climate-resilient aquaculture and culture-based fisheries through adaptation of abiotic stresses: a review

Climate change is an inevitable event that obstructs the output of aquaculture farms and culture-based fisheries in open waters. It poses a serious threat to global food security, altering biodiversity, ecosystems, and global fish output by displacing fish stocks from their natural habitats. When compared to freshwater aquaculture, marine/coastal aquaculture is more affected. To combat the effects of climate change, several mitigation methods and adaptations are being implemented, emphasizing future demands of affordable protein. Selective breeding, species diversification, and aquaculture systems like integrated multi-trophic aquaculture, aquaponics, and recirculating aquaculture system are some of the most widely accepted and adapted solutions. Further research on intervention in seed and feed in terms of quality improvement, bioresource utilization, and technological and genetic improvement is required. Climate change policies from the government are also essential. The present study differs from previous reviews by portraying the various abiotic stress factors contributing to the drastic climate change, encompassing adaptation strategies followed in distinct aquaculture sources such as freshwater, inland saline water, brackish water, coastal waters, and culture-based capture fisheries with its future implications.

Continue reading ‘Sustainable development of climate-resilient aquaculture and culture-based fisheries through adaptation of abiotic stresses: a review’

Effects of oyster aquaculture on carbon capture and removal in a tropical mangrove lagoon in southwestern Taiwan

Highlights

  • Mangroves acted as a key source of DIC and TA in tropical lagoon.
  • Oyster shell formation plays a significant role in decreasing TA.
  • DIC declined due to photosynthesis by phytoplankton.
  • Oyster benefit carbon capture by preying phytoplankton.
  • Oyster farming contributes to carbon capture in a mangrove-dominated lagoon.
Graphical abstract

Abstract

Blue carbon ecosystems (BCEs) are a promising resource for the mitigation of global warming; however, climate spectrums and anthropogenic activities could influence the fragile balance of BCEs as carbon sinks or sources. We assess how oyster farming affects dissolved inorganic carbon (DIC) and total alkalinity (TA) on CO2 fluxes in a mangrove-dominated lagoon. Water physical, chemical and biological parameters were recorded by in-situ buoys within the lagoon and at its inflow. Structural equation modeling was adopted to clarify the factors/processes controlling the partial pressure of CO2 (pCO2). A three-dimensional environmental model followed by a conceptual DIC model was used to quantify the spatiotemporal patterns of capture and release of DIC and TA by oyster production. The results showed that 49% of TA and DIC released from mangroves was depleted by oyster shell formation. DIC was reduced by algal photosynthesis and algal was served as a food source supporting oyster production. Annual oyster production through phytoplankton photosynthesis accounted for 11% of the atmosphere carbon inflows, suggesting that oyster production served as a significant atmospheric/terrestrial carbon sink in the lagoon. The results indicate that mangroves benefit local oyster production by acting as an important source of DIC and TA, and that the oyster aquaculture contributed to carbon capture in a mangrove-dominated lagoon ecosystem.

Continue reading ‘Effects of oyster aquaculture on carbon capture and removal in a tropical mangrove lagoon in southwestern Taiwan’

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