Ocean acidification (OA) can impact aquaculture because reduced pH may negatively affect the calcification in bivalve species. Photosynthetic activity can naturally generate an OA buffering effect, favouring the calcification process by increasing the surrounding seawater pH. Therefore, the incorporation of macroalgae into bivalve farms may be a strategy to mitigate the impacts of acidification on the industry. In this study, we evaluated the modification of seawater chemistry by the metabolic activity of the blue mussel Mytilus chilensis and three macroalgae (Ulva sp., Chondracanthus chamissoi and Macrocystis pyrifera), in monocultures and co-cultures under ambient and acidified initial conditions in three closed-environment experiments. In all three experiments, photosynthesis and respiration modulated seawater chemistry, resulting in higher values of pH, oxygen concentrations, and aragonite saturation state (ΩAra) in macroalgal monocultures compared to mussel monoculture. In co-cultures, pH, oxygen concentrations and ΩAra were higher than in mussel monoculture but lower than in macroalgal monoculture. In co-cultures, the OA buffering effect (pH > 7.7, ΩAra > 1) was observed during daytime, but unfavourable conditions for calcification were observed during nighttime. These results are species-specific, with a greater capacity for pH increase for Ulva sp. and Ch. chamissoi and limited capacity for M. pyrifera in both initial pH treatments. Results of the enclosed environment experiments indicate that the presence of macroalgae in co-cultures did not guarantee favourable conditions for mussel calcification in acidified conditions.
Continue reading ‘Evaluating the ability of macroalgae to create a chemical refuge for bivalves under ocean acidification conditions in closed-environment experiments’Archive Page 89
Evaluating the ability of macroalgae to create a chemical refuge for bivalves under ocean acidification conditions in closed-environment experiments
Published 26 January 2024 Science ClosedTags: chemistry, laboratory, mitigation, South Pacific
Season influences interspecific responses of canopy-forming kelps to future warming and acidification at high latitude
Published 26 January 2024 Science ClosedTags: algae, biological response, growth, laboratory, morphology, multiple factors, North Pacific, performance, physiology, temperature
Variability in primary producers’ responses to environmental change may buffer higher trophic levels against shifts in basal resource composition. Then again, in instances where there is a lack of functional redundancy because consumers rely on a few species to meet their energetic requirements at specific times of the year, altered community production dynamics may significantly impact food web resilience. In high-latitude kelp forests, a complementary annual phenology of seaweed production supports coastal marine consumers’ metabolic needs across large seasonal variations in their environment. Yet, marine consumers in these systems may face significant metabolic stress under the pronounced low pH conditions expected in future winters, particularly if they lack the resources to support their increased energetic demands. In this study, we investigate how the growth and nutritional value of three dominant, coexisting macroalgal species found in subpolar kelp forests will respond to ocean acidification and warming in future winter and summer seasons. We find that the three kelps Macrocystis pyrifera, Hedophyllum nigripes, and Neoagarum fimbriatum differ in their vulnerability to future environmental conditions, and that the seasonal environmental context of nutrient and light availability shapes these responses. Our results suggest that poleward fringe populations of M. pyrifera may be relatively resilient to anticipated ocean warming and acidification. In contrast, ocean warming conditions caused a decrease in the biomass and nutritional quality of both understory kelps. Considering the unique production phenology of H. nigripes, we emphasize that negative impacts on this species in future winters may be of consequence to consumer energetics in this system. This work highlights how interspecific variation in autotrophs’ responses to global change can disrupt the diversity and phenological structure of energy supply available to higher trophic levels.
Continue reading ‘Season influences interspecific responses of canopy-forming kelps to future warming and acidification at high latitude’The combined effects of acidification and acute warming on the embryos of Pacific herring (Clupea pallasii)
Published 26 January 2024 Science ClosedTags: biological response, fish, laboratory, mortality, multiple factors, North Pacific, performance, physiology, reproduction, respiration, temperature
Anthropogenic climate change is projected to affect marine ecosystems by challenging the environmental tolerance of individuals. Marine fishes may be particularly vulnerable to emergent climate stressors during early life stages. Here we focus on embryos of Pacific herring (Clupea pallasii), an important forage fish species widely distributed across the North Pacific. Embryos were reared under a range of temperatures (10-16°C) crossed with two pCO2 levels (600 and 2000 μatm) to investigate effects on metabolism and survival. We further tested how elevated pCO2 affects critical thermal tolerance (CTmax) by challenging embryos to short-term temperature fluctuations. Experiments were repeated on embryos collected from winter and spring spawning populations to determine if spawning phenology corresponds with different limits of environmental tolerance in offspring. We found that embryos could withstand acute exposure to 20°C regardless of spawning population or incubation treatment, but that survival was greatly reduced after 2-3 hours at 25°C. We found that pCO2 had limited effects on CTmax. The survival of embryos reared under chronically warm conditions (12°, 14°, or 16°C) was significantly lower relative to 10°C treatments in both populations. Oxygen consumption rates (MO2) were also higher at elevated temperatures and pCO2 levels. However, heart contraction measurements made 48 hours after CTmax exposure revealed a greater increase in heart rate in embryos reared at 10°C compared to 16°C, suggesting acclimation at higher incubation temperatures. Our results indicate that Pacific herring are generally tolerant of pCO2 but are vulnerable to acute temperature stress. Importantly, spring-spawning embryos did not clearly exhibit a higher tolerance to heat stress compared to winter offspring.
Continue reading ‘The combined effects of acidification and acute warming on the embryos of Pacific herring (Clupea pallasii)’Acidity of Antarctic waters could double by century’s end, threatening biodiversity
Published 26 January 2024 Press releases ClosedThe acidity of Antarctica’s coastal waters could double by the end of the century, threatening whales, penguins and hundreds of other species that inhabit the Southern Ocean, according to new CU Boulder research.
Scientists projected that by 2100, the upper 650 feet (200 meters) of the ocean—where much marine life resides—could see more than a 100% increase in acidity compared with 1990s levels. The paper, appeared Jan. 4 in the journal Nature Communications.
“The findings are critical for our understanding of the future evolution of marine ecosystem health,” said Nicole Lovenduski, the paper’s co-author and the interim director of CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR).
The oceans play an important role as a buffer against climate change by absorbing nearly 30% of the CO2 emitted worldwide. But as more CO2 dissolves in the oceans, the seawater becomes more acidic. “Human-caused CO2 emissions are at the heart of ocean acidification,” said Cara Nissen, the paper’s first author and a research scientist at INSTAAR.
The Southern Ocean, which surrounds Antarctica, is particularly susceptible to acidification, partly because colder water tends to absorb more CO2. Ocean currents in the area also contribute to the relatively acidic water conditions.
Using a computer model, Nissen, Lovenduski and the team simulated how the seawater of the Southern Ocean would change in the 21st century. They found it would become more acidic by 2100, and the situation would be severe if the world fails to cut emissions.
“It’s not just the top layer of the ocean. The entire water column of the coastal Southern Ocean, even at the bottom, could experience severe acidification,” Nissen said.
The team then investigated the conditions specifically in Antarctica’s marine protected areas (MPAs). Human activities, such as fishing, are restricted in these regions to protect biodiversity. Currently, there are two MPAs in the Southern Ocean, covering about 12% of water in the region. Scientists have proposed designating three more MPAs to an international council in the past years, which would encompass about 60% of the Antarctic Ocean.
The team’s model showed that both adopted and proposed MPAs would experience significant acidification by the end of the century.
For example, under the highest-emission scenario, where the world makes no efforts to cut emissions, the average acidity of the water in the Ross Sea region—the world’s largest MPA off the northern tip of Antarctica—would increase by 104% over 1990s levels by 2100. Under an intermediate emissions scenario, the water would still become 43% more acidic.
“It’s surprising to me how severe ocean acidification would be in these coastal waters,” Nissen said.
Previous studies have shown that phytoplankton, a group of algae that forms the basis of the marine food web, grow at a slower rate or die out when the water becomes too acidic. Acidic water also weakens the shells of organisms like sea snails and sea urchins. These changes could disrupt the food web, eventually impacting top predators like whales and penguins.
The Weddell Sea is one of the three proposed MPAs located off the coast of the Antarctic Peninsula. Nissen said scientists think the Weddell Sea region could act as a climate change sanctuary for organisms, mainly because this area has the highest levels of sea ice coverage in the Antarctic. The ice shields the ocean from warming and prevents the seawater underneath from absorbing CO2 from the air, thereby reducing the rate of acidification. In addition, the region has little human activity to date.
But the model suggested that as the planet continues to warm, the sea ice will melt, and the Weddell Sea region will experience acidification on par with other MPAs under intermediate to high emission scenarios, but with a slightly delayed progression.
“The result shows that establishing the Weddell Sea region as a protected area should have high priority,” Nissen said.
“As a scientist who typically studies the open ocean, I tend to think of Antarctic coastal areas as a conduit for climate signals to reach the global, deep ocean. This study reminded me that these dynamic Antarctic coastal areas are also themselves capable of rapid change,” Lovenduski said.
The study suggests that the world could only avoid severe ocean acidification of the Southern Ocean under the lowest emission scenario, where society cuts CO2 emissions quickly and aggressively.
“We still have time to select our emission pathway, but we don’t have much,” Nissen said.
CU Boulder Today, 26 January 2024. Article.
Acidification of the global surface ocean: what we have learned from observations
Published 25 January 2024 Science ClosedTags: chemistry, globalmodeling, modeling, review
The chemistry of the global ocean is rapidly changing due to the uptake of anthropogenic carbon dioxide (CO2). This process, commonly referred to as ocean acidification (OA), is negatively impacting many marine species and ecosystems. In this study, we combine observations in the global surface ocean collected by NOAA Pacific Marine Environmental Laboratory and Atlantic Oceanographic and Meteorological Laboratory scientists and their national and international colleagues over the last several decades, along with model outputs, to provide a high-resolution, regionally varying view of global surface ocean carbon dioxide fugacity, carbonate ion content, total hydrogen ion content, pH on total scale, and aragonite and calcite saturation states on selected time intervals from 1961 to 2020. We discuss the major roles played by air-sea anthropogenic CO2 uptake, warming, local upwelling processes, and declining buffer capacity in controlling the spatial and temporal variability of these parameters. These changes are occurring rapidly in regions that would normally be considered OA refugia, thus threatening the protection that these regions provide for stocks of sensitive species and increasing the potential for expanding biological impacts.
Continue reading ‘Acidification of the global surface ocean: what we have learned from observations’Severe 21st-century ocean acidification in Antarctic Marine Protected Areas
Published 25 January 2024 Science ClosedTags: Antarctic, chemistry, modeling, policy, regionalmodeling
Antarctic coastal waters are home to several established or proposed Marine Protected Areas (MPAs) supporting exceptional biodiversity. Despite being threatened by anthropogenic climate change, uncertainties remain surrounding the future ocean acidification (OA) of these waters. Here we present 21st-century projections of OA in Antarctic MPAs under four emission scenarios using a high-resolution ocean–sea ice–biogeochemistry model with realistic ice-shelf geometry. By 2100, we project pH declines of up to 0.36 (total scale) for the top 200 m. Vigorous vertical mixing of anthropogenic carbon produces severe OA throughout the water column in coastal waters of proposed and existing MPAs. Consequently, end-of-century aragonite undersaturation is ubiquitous under the three highest emission scenarios. Given the cumulative threat to marine ecosystems by environmental change and activities such as fishing, our findings call for strong emission-mitigation efforts and further management strategies to reduce pressures on ecosystems, such as the continuation and expansion of Antarctic MPAs.
Continue reading ‘Severe 21st-century ocean acidification in Antarctic Marine Protected Areas’Building unique collaborative global marine CO2 observatories
Published 25 January 2024 Science ClosedTags: chemistry, field, methods, review
The NOAA Pacific Marine Environmental Laboratory (PMEL) carbon program has made sustained investments over the last two decades in equipment development, autonomous sampling, and virtual support that undergird the global carbon observing infrastructure. As a result, the program plays an integral role in supporting ocean carbon research with collaborating institutions worldwide (Sutton and Sabine, 2023, in this issue).
Here, we discuss the field support and data product strategies we developed to build a successful moored autonomous air-sea CO2 and ocean acidification program that relies on moored buoys maintained by other collaborators. The most critical component of our program is partnering with other agencies, universities, and oceanographic institutions. Sharing resources and results allows scientists to collaborate on global climate issues at an international level. We provide instrument refurbishments, real-time (remote) troubleshooting, data handling and dissemination, and centralized coordination. Our partners provide ship and personnel-based resources for deployment/recovery of moorings as well as in-person troubleshooting. No one institution can provide all the physical support necessary for a global array of buoys, but many hands make light work when the effort is dispersed among multiple partnerships. To date, we have partnered with over 100 individuals from more than 20 US and global institutions (Figure 1) in support of nearly 50 autonomous air-sea CO2 and ocean acidification sites since 2003.
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Continue reading ‘Building unique collaborative global marine CO2 observatories’Early stage ecological communities on artificial algae showed no difference in diversity and abundance under ocean acidification
Published 24 January 2024 Science ClosedTags: abundance, algae, annelids, biological response, BRcommunity, calcification, chemistry, community composition, crustaceans, echinoderms, field, Mediterranean, mesocosms, mitigation, mollusks, otherprocess, photosynthesis, protists, respiration
Marine habitat-forming species create structurally complex habitats that host macroinvertebrate communities characterized by remarkable abundance and species richness. These habitat-forming species also play a fundamental role in creating favourable environmental conditions that promote biodiversity. The deployment of artificial structures is becoming a common practice to help offset habitat loss although with mixed results. This study investigated the suitability of artificial flexible turfs mimicking the articulated coralline algae (mimics) as habitat providers and the effect of ocean acidification (OA) on early stage ecological communities associated to flexible mimics and with the mature community associated to Ellisolandia elongata natural turfs. The mimics proved to be a suitable habitat for early stage communities. During the OA mesocosms experiment, the two substrates have been treated and analysed separately due to the difference between the two communities. For early stage ecological communities associated with the mimics, the lack of a biologically active substrate does not exacerbate the effect of OA. In fact, no significant differences were found between treatments in crustaceans, molluscs and polychaetes diversity and abundance associated with the mimics. In mature communities associated with natural turfs, buffering capability of E. elongata is supporting different taxonomic groups, except for molluscs, greatly susceptible to OA.
Continue reading ‘Early stage ecological communities on artificial algae showed no difference in diversity and abundance under ocean acidification’Local scale extreme low pH conditions and genetic differences shape phenotypic variation in a broad dispersal copepod species
Published 24 January 2024 Science ClosedTags: adaptation, biological response, chemistry, crustaceans, field, molecular biology, morphology, otherprocess, reproduction, South Pacific
Extreme low pH events in estuaries and upwelling areas can modulate the phenotypic and genetic diversity of natural populations. To test this hypothesis, we explored the linkage between local scale extreme low pH events, genetic diversity, and variation in fecundity-related traits (body size, egg size, and egg production rate) in the broad-dispersal copepod Acartia tonsa. We assessed genetic and phenotypic characteristics of populations by contrasting extreme low pH environments (upwelling and temperate estuary) in the coastal Southeast Pacific, under natural and experimental conditions. These populations showed significant genetic differentiation with higher diversity in mitochondrial and nuclear loci (encoding mtCOI and 18S rRNA) in the estuarine population. Copepods from this population are exposed to more frequent extreme low pH events (< 7.7), and the adult females exhibit consistent phenotypic variation in body size, egg size, and egg production rate across different cohorts. Experimental acclimation to extreme low pH conditions revealed no significant differences in fecundity-related traits between A. tonsa populations. Although these results partially support our hypothesis, the experimental findings suggest other drivers might also influence phenotypic differences in the local environments.
Continue reading ‘Local scale extreme low pH conditions and genetic differences shape phenotypic variation in a broad dispersal copepod species’High nutrient availability modulates photosynthetic performance and biochemical components of the economically important marine macroalga Kappaphycus alvarezii (Rhodophyta) in response to ocean acidification
Published 24 January 2024 Science ClosedTags: algae, biological response, laboratory, multiple factors, North Pacific, nutrients, photosynthesis, physiology
Increased atmospheric CO2 concentrations not only change the components of inorganic carbon system in seawater, resulting in ocean acidification, but also lead to decreased seawater pH, resulting in ocean acidification. Consequently, increased inorganic carbon concentrations in seawater provide a sufficient carbon source for macroalgal photosynthesis and growth. Increased domestic sewage and industrial wastewater discharge into coastal areas has led to nutrient accumulation in coastal seawaters. Combined with elevated pCO2 (1200 ppmv), increased nutrient availability always stimulates the growth of non-calcifying macroalgae, such as red economical macroalga Gracilariopsis lemaneiformis. Here, we evaluated the interactive effects of nutrients with elevated pCO2 on the economically important marine macroalga Kappaphycus alvarezii (Rhodophyta) in a factorial 21-day coupling experiment. The effects of increased nutrient availability on photosynthesis and photosynthetic pigments of K. alvarezii were greater than those of pCO2 concentration. The highest Fv/Fm values (0.660 ± 0.019 and 0.666 ± 0.030, respectively) were obtained at 2 μmol L−1 of NO3–N at two pCO2 levels. Under the elevated pCO2 condition, the Chl-a content was lowest (0.007 ± 0.004 mg g−1) at 2 μmol L−1 of NO3–N and highest (0.024 ± 0.002 mg g−1) at 50 μmol L−1 of NO3–N. The phycocyanin content was highest (0.052 ± 0.012 mg g−1) at 150 μmol L−1 of NO3–N under elevated pCO2 condition. The malondialdehyde content declined from 32.025 ± 4.558 nmol g−1 to 26.660 ± 3.124 nmol g−1 with the increased nutrients at under low pCO2. To modulate suitable adjustments, soluble biochemical components such as soluble carbohydrate, soluble protein, free amino acids, and proline were abundantly secreted and were likely to protect the integrity of cellular structures under elevated nutrient availability. Our findings can serve as a reference for cultivation and bioremediation methods under future environmental conditions.
Continue reading ‘High nutrient availability modulates photosynthetic performance and biochemical components of the economically important marine macroalga Kappaphycus alvarezii (Rhodophyta) in response to ocean acidification’The correlation between echinoderms diversity and physicochemical parameters in marine pollution: a case study of the Persian Gulf coastline
Published 24 January 2024 Science ClosedTags: abundance, biological response, echinoderms, field, Indian, morphology, otherprocess
This study was conducted with the aim of investigating the correlation between echinoderms diversity and physicochemical parameters in the Persian Gulf coastline in Bushehr province in 4 seasons from March to December 2017. The physicochemical parameters including water temperature, dissolved oxygen (DO), electrical conductivity (EC), salinity, pH and turbidity were measured at each sampling location. The results showed a significant correlation between echinoderms diversity and physicochemical parameters. The correlation coefficient of the Astropecten polyacanthus species with the parameters of temperature, DO, EC, salinity and turbidity was reported as -0.41, 0.64, -0.25, -0.44 and 0.60 respectively. This coefficient for the Ophiothrix fragilis species was reported as -0.68, 0.70, -0.21, -0.36 and -0.55 respectively. The results demonstrated that the most sensitive species were Astropecten polyacanthus and Ophiothrix fragilis respectively. The different species of echinoderms can be used as biological indicators of pollution in evaluating the physicochemical quality of marine environments.
The vulnerability of World Heritage seagrass habitats to climate change
Published 23 January 2024 Science ClosedTags: adaptation, biological response, otherprocess, performance, phanerogams
Seagrass is an important natural attribute of 28 World Heritage (WH) properties. These WH seagrass habitats provide a wide range of services to adjacent ecosystems and human communities, and are one of the largest natural carbon sinks on the planet. Climate change is considered the greatest and fastest-growing threat to natural WH properties and evidence of climate-related impacts on seagrass habitats has been growing. The main objective of this study was to assess the vulnerability of WH seagrass habitats to location-specific key climate stressors. Quantitative surveys of seagrass experts and site managers were used to assess exposure, sensitivity and adaptive capacity of WH seagrass habitats to climate stressors, following the Climate Vulnerability Index approach. Over half of WH seagrass habitats have high vulnerability to climate change, mainly from the long-term increase in sea-surface temperature and short-term marine heatwaves. Potential impacts from climate change and certainty scores associated with them were higher than reported by a similar survey-based study from 10 years prior, indicating a shift in stakeholder perspectives during the past decade. Additionally, seagrass experts’ opinions on the cumulative impacts of climate and direct-anthropogenic stressors revealed that high temperature in combination with high suspended sediments, eutrophication and hypoxia is likely to provoke a synergistic cumulative (negative) impact (p < .05). A key component contributing to the high vulnerability assessments was the low adaptive capacity; however, discrepancies between adaptive capacity scores and qualitative responses suggest that managers of WH seagrass habitats might not be adequately equipped to respond to climate change impacts. This thematic assessment provides valuable information to help prioritize conservation actions, monitoring activities and research in WH seagrass habitats. It also demonstrates the utility of a systematic framework to evaluate the vulnerability of thematic groups of protected areas that share a specific attribute.
Continue reading ‘The vulnerability of World Heritage seagrass habitats to climate change’Effects of excess atmospheric CO2 on calcium carbonate producers along the Red Sea coast of Yemen: its risk and socio-economic impacts
Published 23 January 2024 Science ClosedTags: chemistry, field, Red Sea
The formation of calcite and aragonite, integral components of marine organisms’ skeletons, is contingent on the degree of saturation (W) of seawater with respect to carbonate minerals. The decrease in W, driven by an excess of atmospheric carbon dioxide, poses challenges for calcifying organisms in their ability to create and maintain their skeletal structures and shells. As a result, we conducted a collection of surface seawater samples from various locations along the Red Sea coast of Yemen to address three key objectives: (1) ascertain the current W values for calcite and aragonite, (2) project alterations in these values attributable to seawater pH reduction (acidification) over the next 50 and 200 years, and (3) assess potential ecological consequences and risks associated with these impeding changes. During both winter and summer, we conducted measurements of various oceanographic parameters, including temperatures (ToC), salinities (S), pH values, and total alkalinities (TA). In winter season, these parameters were ToC = 26.4±0.5oC, S = 36.9±0.5, pH = 8.16±0.3 and TA = 2.409±0.104 meq/Kg, whereas in summer ToC = 34.6±0.6oC, S = 38.5±0.2, pH = 8.11±0.12 and TA = 2.428±0.036 meq/Kg. These measured parameters served as crucial inputs for the assessment of carbonate chemistry, including the determination of seawater’s W values with respect to both calcite and aragonite. The findings indicated that surface seawater was supersaturated with respect to both calcite and aragonite. The percent degree of saturation (%W) for calcite was 553±89% in winter and 607±77% in summer, while for aragonite was 367±58% in winter and 415±53% in summer. Over the course of the next five decades, the surface seawater %W with respect to calcite is projected to decrease approximately 464±111% during winter months and 499±78% during summer. At the same time, it is expected to decline to around 251±60% in winter and 341±53% in summer for aragonite. In the next two centuries, these percentages are anticipated to further decrease to 249±57% in winter and 281±48% in summer for calcite, and to 135±31% in winter and 192±33% in summer for aragonite. Acidification of seawater will have serious environmental consequences on the marine and coastal habitats of the Red Sea of Yemen and the entire region. Further studies are warranted to monitor and investigate the occurrence, distribution, mineralogy of corals, and the effects of physical and chemical parameter variations on their growth in the region.
Continue reading ‘Effects of excess atmospheric CO2 on calcium carbonate producers along the Red Sea coast of Yemen: its risk and socio-economic impacts’Biochemical adaptability of the relationship between tropical hard corals and photosynthetic symbiotic algae under climate change
Published 23 January 2024 Science ClosedTags: adaptation, algae, BRcommunity, corals, otherprocess, performance, review
Tropical coral reefs, a vital component of the global marine ecosystem, are currently under threat from climate change factors such as rising temperatures, ocean acidification, and extreme weather events. High temperatures induce coral bleaching, resulting in the loss of their energy supply and an acceleration of metabolic rates, rendering them more vulnerable. Ocean acidification affects the formation of calcium carbonate skeletons in symbiotic algae and decreases photosynthetic efficiency, further exacerbating the risk of damage to the symbiotic algae in high-temperature conditions. Extreme weather events directly cause physical damage to corals and alter marine environments, reducing their chances of survival. This review focuses on the impact of climate change on the biochemical adaptability between tropical hard corals and photosynthetic symbiotic algae, exploring their ecological relationship, the influence of climate change on this relationship, and the adaptive mechanisms. Understanding the adaptive mechanisms between hard corals and symbiotic algae is crucial for developing conservation strategies and management plans to maintain the functionality and biodiversity of coral reef ecosystems. It also aids in ensuring the survival and prosperity of this delicate relationship under the challenges posed by climate change, allowing future generations to continue enjoying the magnificence of tropical coral reefs.
Continue reading ‘Biochemical adaptability of the relationship between tropical hard corals and photosynthetic symbiotic algae under climate change ‘Estuary is the promising site for olivine-dissolution engineering: Insight from olivine mineralogy
Published 22 January 2024 Science ClosedTags: mitigation
To keep global warming below 1.5 °C to address the threats posed by global climate change, various geoengineering strategies based on increasing the negative carbon emissions in oceans have been proposed, considering the ocean the largest reservoir of carbon [1, 2]. Dissolution of silicate minerals, such as olivine, is one promising engineering that not only depletes carbon dioxide (CO2) but reduces ocean acidification. Olivine is the most abundant mineral in the earth’s upper mantle [3]. Olivine consists of a hexagonal close-packed array of oxygen atoms from Si-O tetrahedrons lying parallel to (100) (Figure 1) [4]. Olivine is a magnesium iron silicate with the formula (Mg2+, Fe2+)2SiO4 and has an orthorhombic crystal system. In olivine, the Mg2+ and Fe2+ ions form a complete isomorphic series, and forsterite and fayalite are the two end-member minerals of the olivine group. The Mg-O and Fe-O bonds in olivine have a much lower bond energy than thatof Si-O bonds [4]. Moreover, bridging oxygen atoms lack between Si and Mg, and thus Mg2+ is more easily released from the olivine’s surface during dissolution [5]. The dissolution reaction of olivine depends on H+ ions, which form an activated complex with Mg2+ and enhance its removal from the olivine’s surface, damaging its structures [5]. Therefore, the dissolution of olivine led to a significant increase in seawater alkalinity. And meanwhile, olivine dissolution also consumes CO2.
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Continue reading ‘Estuary is the promising site for olivine-dissolution engineering: Insight from olivine mineralogy’Atmospheric CO2 emissions and ocean acidification from bottom-trawling
Published 22 January 2024 Science ClosedTags: biogeochemistry, chemistry, fisheries, globalmodeling, modeling
Trawling the seafloor can disturb carbon that took millennia to accumulate, but the fate of that carbon and its impact on climate and ecosystems remains unknown. Using satellite-inferred fishing events and carbon cycle models, we find that 55-60% of trawling-induced aqueous CO2 is released to the atmosphere over 7-9 years. Using recent estimates of bottom trawling’s impact on sedimentary carbon, we found that between 1996-2020 trawling could have released, at the global scale, up to 0.34-0.37 Pg CO2 yr-1 to the atmosphere, and locally altered water pH in some semi-enclosed and heavy trawled seas. Our results suggest that the management of bottom-trawling efforts could be an important climate solution.
Continue reading ‘Atmospheric CO2 emissions and ocean acidification from bottom-trawling’Synergizing climate change and ocean regimes: a comprehensive international legal approach for ocean acidification governance
Published 22 January 2024 Uncategorized ClosedTags: policy
Ocean acidification poses a myriad of challenges, particularly to marine environments and ecosystems. Its negative repercussions are equally obvious from a human-centric perspective. Despite efforts to address ocean acidification through various international legal frameworks, current international legal frameworks, such as the United Nations Convention on the Law of the Sea and the United Nations Convention on Climate Change, which represent the climate change regime and the ocean regime , respectively, fall short of adequately addressing ocean acidification challenges. Because of the climate change regime’s atmospheric -centered perspective and the ocean regime’s pollution-oriented perspective, ocean acidification falls between the cracks and is not a priority for either regime. To adequately address the issues posed by ocean acidification, a concerted effort between the the legal regime addressing climate change and the legal regime regulating maritime affairs is crucial. This effort might be realized by developing a robust governance system that encompasses both of these regimes, which are specifically tailored to tackle ocean acidification. Given the complexity of ocean acidification governance, the distribution of roles for both regimes should be thoroughly examined. Due to its broad reach, the ocean regime might take the lead in directing the trajectory of ocean acidification, while the climate change regime might provide assistance within the context of ocean acidification governance. Active mutual reference and due diligence obligations could be employed in this scenario to bridge the gaps created by both the climate change regime and the ocean regime regarding ocean acidification. The active interaction between these regimes might pave the way for proper ocean acidification governance in order to meet the challenges posed by ocean acidification.
Continue reading ‘Synergizing climate change and ocean regimes: a comprehensive international legal approach for ocean acidification governance’Collagen-mediated calcium carbonate polymorph modulation─a nature-inspired general chemistry experiment utilizing modern characterization tools, including SEM, EDS, and FTIR-ATR spectroscopy
Published 19 January 2024 Science ClosedTags: chemistry, education, laboratory, methods
This manuscript introduces a novel General Chemistry experiment designed to incorporate modern instrumental methods and bioinspired materials in the context of marine environments and sustainability. The experiment explores the influence of collagen on the formation of calcium carbonate (CaCO3) polymorphs over two 2 h lab sessions, focusing on vaterite, aragonite, and calcite. By engaging in this experiment, students reinforce their knowledge, learn key concepts in General Chemistry, and develop essential skills required for the course. Additionally, students use advanced analytical techniques, such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), to investigate crystal formation and determine polymorph compositions. The experiment also simulates the effects of ocean acidification on CaCO3 crystals. Student feedback emphasizes the value of practical application and real-world relevance, making this experiment a valuable addition not only to General Chemistry courses, but also to advanced courses including analytical methods, physical chemistry, nanotechnology, environment science, or material science.
Continue reading ‘Collagen-mediated calcium carbonate polymorph modulation─a nature-inspired general chemistry experiment utilizing modern characterization tools, including SEM, EDS, and FTIR-ATR spectroscopy’Impacts of ocean acidification and warming on the release and activity of the barnacle waterborne settlement pheromone, adenosine
Published 19 January 2024 Science ClosedTags: biological response, crustaceans, laboratory, multiple factors, North Pacific, performance, physiology, temperature
The effects of ocean acidification (OA) and warming on the physiological processes of many marine species have been well documented. However, far less is known about the impacts of these global variables on chemical communication. In this study, we identified the barnacle waterborne settlement pheromone (BWSP) of Balanus albicostatus as adenosine (Ado). Our results showed that neither elevated temperature (30 °C vs. ambient 26 °C) nor elevated pCO2 (1000 μatm vs. ambient 400 μatm) significantly affected the release of Ado from B. albicostatus adults. Exposure to elevated temperature and OA did not impair larval cue perception for settlement in B. albicostatus; however, OA inhibited settlement under elevated temperature in the absence/presence of BWSP, and elevated temperature induced larval settlement only in the presence of BWSP under ambient pCO2 condition. These results provided important insights into barnacle aggregation behavior in changing oceans and may help to predict the consequences of climate change on barnacle populations.
