Ocean acidification and eutrophication are two important environmental stressors. They inevitably impact marine macroalgae, and hence the coastal ecosystem of China. Saccharina japonica, as the main culture species in China, is suffering the harmful golden tide caused by Sargassum horneri. However, it remains unclear whether the detrimental effects of S. horneri on S. japonica cultivation become more severe in future acidified and eutrophic scenario. In this study, we respectively investigated the effects of pCO2 (400 µatm and 1000 µatm) and nutrients (non-enriched and enriched seawater) on the growth, photosynthesis, respiration, chlorophyll contents, and tissue nitrogen of S. japonica and S. horneri. Results indicated that enrichment of nutrients contributed S. horneri to utilize HCO3−. The carbon acquisition pathway shifted from HCO3− to CO2 in S. japonica, while S. horneri remained using HCO3− regulated by nutrient enrichment. S. horneri exhibited better photosynthetic traits than S. japonica, with a higher level of net photosynthetic rate and chlorophyll contents at elevated pCO2 and enriched nutrients. Tissue nitrogen also accumulated richly in the thalli of S. horneri under higher pCO2 and nutrients. Significant enhancement in growth was only detected in S. horneri under synergistic stress. Together, S. horneri showed competitive dominance in current study. These findings suggest that increasing risk of golden tide in acidified and eutrophic ocean can most likely result in great damage to S. japonica cultivation.
Continue reading ‘The brown algae Saccharina japonica and Sargassum horneri exhibit species-specific responses to synergistic stress of ocean acidification and eutrophication’Archive Page 220
The brown algae Saccharina japonica and Sargassum horneri exhibit species-specific responses to synergistic stress of ocean acidification and eutrophication
Published 19 August 2021 Science ClosedTags: algae, biological response, laboratory, morphology, multiple factors, North Pacific, nutrients, photosynthesis, physiology, respiration
Diel pCO2 fluctuations alter the molecular response of coral reef fishes to ocean acidification conditions
Published 19 August 2021 Science ClosedTags: biological response, BRcommunity, fish, laboratory, molecular biology
Environmental pCO2 variation can modify the responses of marine organisms to ocean acidification, yet the underlying mechanisms for this effect remain unclear. On coral reefs, environmental pCO2 fluctuates on a regular day-night cycle. Effects of future ocean acidification on coral reef fishes might therefore depend on their response to this diel cycle of pCO2. To evaluate the effects on the brain molecular response, we exposed two common reef fishes (Acanthochromis polyacanthus and Amphiprion percula) to two projected future pCO2 levels (750 and 1,000 µatm) under both stable and diel fluctuating conditions. We found a common signature to stable elevated pCO2 for both species, which included the downregulation of immediate early genes, indicating lower brain activity. The transcriptional program was more strongly affected by higher average pCO2 in a stable treatment than for fluctuating treatments, however, the largest difference in molecular response was between stable and fluctuating pCO2 treatments. This indicates that a response to a change in environmental pCO2 conditions is different for organisms living in a fluctuating than in stable environments. This differential regulation was related to steroid hormones and circadian rhythm (CR). Both species exhibited a marked difference in the expression of CR genes among pCO2 treatments, possibly accommodating a more flexible adaptive approach in the response to environmental changes. Our results suggest that environmental pCO2 fluctuations might enable reef fishes to phase shift their clocks and anticipate pCO2 changes, thereby avoiding impairments and more successfully adjust to ocean acidification conditions.
Continue reading ‘Diel pCO2 fluctuations alter the molecular response of coral reef fishes to ocean acidification conditions’Near-future oceanic CO2 delays development and growth in early-stage larvae of the endemic New Zealand sea urchin, Evechinus chloroticus
Published 19 August 2021 Science ClosedTags: biological response, echinoderms, laboratory, morphology, physiology, reproduction, South Pacific
Under the ocean acidification (OA) conditions predicted for 2100, the larval stages of temperate sea urchins are smaller, with reduced and abnormal skeleton and changes in metabolic rate. Here, we measure the impact of near-future and long-term predictions of atmospheric pCO2 levels on the early development of the echinometrid sea urchin Evechinus chloroticus using single male:female crosses, effect sizes and a within-study meta-analysis. Using the developmental signpost of the 16-cell stage, we show a mean delay of 5.11 min at pH 7.7 and 11.85 min at pH 7.5, which may have flow-on effects to later embryo and larval stages. Echinopluteus larvae raised in OA conditions (pH 7.7, 7.5) were ~ 5–10% smaller in body length and 10–12% smaller in arm length than controls. Metabolic rate was highly variable between single male:female crosses—increasing in some crosses, decreasing in others—with a non-significant effect size in the meta-analysis. Preliminary experiments suggest that metabolic rate changes may be impacted by loss of mitochondrial function at low pH. Single male:female crosses showed variable OA responses in all measurements, suggesting that when assessing the population-level impacts of OA on early development of sea urchins there is a need to include high levels of biological replication.
Continue reading ‘Near-future oceanic CO2 delays development and growth in early-stage larvae of the endemic New Zealand sea urchin, Evechinus chloroticus’Plastic pollution and ocean acidification reduce Antarctic krill development, BAS research
Published 19 August 2021 Press releases Closed
Plastic pollution combined with ocean acidification hinders the development of Antarctic krill in the Southern Ocean, research published in Marine Frontiers reveals.
Antarctic krill (Euphausia superba) are shrimp-like crustaceans that play a critical role in the polar oceans. They are the main diet of whales, penguins and seals and play a critical role in promoting the transport of carbon to the depths of the ocean. However, krill and their habitats are threatened by the impacts of climate change and a wide range of pollutants, including plastics.
Scientists from British Antarctic Survey (BAS), University of Exeter and Plymouth Marine Laboratory looked at the impact of nanoplastic – the smallest form of plastic pollution, invisible to the naked eye and at least 2000 times smaller than a grain of sand – under current and future ocean acidification conditions. Antarctic krill are especially vulnerable to these environmental stressors due to their close association with sea ice, a known area where plastic accumulates and the more rapid ocean acidification at higher latitudes, such as the Southern Ocean.
The team found that krill embryos exposed to nanoplastic pollution combined with future ocean acidification conditions, were least likely to reach later developmental stages compared to embryos exposed to only nanoplastic or ocean acidification conditions as single effects.
Emily Rowlands, lead author and Marine Environmental Ecologist at British Antarctic Survey, says: “Our results provide the first evidence that combined anthropogenic stressors (such as ocean acidification and nanoplastic pollution) can obstruct Antarctic krill development at the earliest and most sensitive embryonic stage of life. Now we need to understand whether these findings are reflective of the wider krill population.”
Dr. Claro Manno, Marine Ecologist, lead of the research project at BAS and co-author indicated that “Ocean acidification, which is where the pH of the ocean decreases, resulting in a less optimal environment for marine wildlife, is expected to increase, along with micro- and nanoplastic pollution as existing ocean plastic degrades. Our results show that it is critical to address plastic pollution in the context of global climate change to understand the full impact on the marine ecosystem.”
The researchers say future research into early development of krill should consider the effects of multiple impacts as a reduction in juvenile krill numbers could have serious consequences for the Antarctic food web and krill fisheries management.
“The effects of combined ocean acidification and nanoplastic exposures on the embryonic development of Antarctic krill”, by Rowlands, E., Galloway, T., Cole M., Lewis, C., Peck, V., Thorpe, S., and Manno, C. is published in the journal Marine Frontiers.
Continue reading ‘Plastic pollution and ocean acidification reduce Antarctic krill development, BAS research’New report shows impacts of climate change and extreme weather in Latin America and Caribbean (text & video)
Published 19 August 2021 Newsletters and reports , Web sites and blogs ClosedTags: report, resource
Climate change and extreme weather are threatening human health and safety, food, water and energy security and the environment in Latin America and the Caribbean. The impacts span the entire region, including Andean peaks, mighty river basins and low-lying islands, according to a new report from the World Meteorological Organization (WMO). It flags concerns about fires and the loss of forests which are a vital carbon sink.
The “State of the Climate in Latin America and the Caribbean 2020” provides a snapshot of the effects of increasing temperatures, changing precipitation patterns, storms and retreating glaciers. It includes transboundary analyses, such as of the drought of the South American Pantanal and the intense hurricane season in Central America-Caribbean. It provides a detailed regional breakdown of worsening global climate change indicators.
The report and an accompanying story map show how marine life, coastal ecosystems and the human communities that depend on them, particularly in Small Island Developing States, are facing increasing threats from ocean acidification and heat and rising sea levels.
The report was released at a high-level conference on 17 August, “Working together for weather, climate and water resilience in Latin America and the Caribbean” under the auspices of WMO, the UN Economic Commission for Latin America and the Caribbean (UNECLAC), and the UN Office for Disaster Risk Reduction (UNDRR).
It follows the release of the Intergovernmental Panel on Climate Change report on Climate Change 2021: the Physical Science basis, which said that temperatures in the region have increased more than the global average and are likely to continue to do so. It also projected changing precipitation patterns, more sea level rise, coastal flooding and marine heatwaves.
Continue reading ‘New report shows impacts of climate change and extreme weather in Latin America and Caribbean (text & video)’Stressors of the Arctic Ocean ecosystems: improved understanding of primary production and ocean acidification
Published 19 August 2021 Presentations ClosedTags: resource, video/audio, webinar recording
The Arctic Ocean is changing faster than any other ocean region in the world. Uptake of anthropogenic carbon, amplified warming, sea ice reduction, coastal erosion, and enhanced riverine runoff are driving important changes in the Arctic Ocean ecosystems through changes in primary production and ocean acidification. However, the current understanding of primary production and ocean acidification in the Arctic remains highly uncertain. Furthermore, projections of both processes by Earth-System Models diverge strongly in this region.
During this webinar, Dr. Terhaar presented:
(1) a modelling study that quantifies the impact of terrigenous nutrients from rivers and coastal erosions on Arctic Ocean primary production, a process that was (wrongly?) neglected so far, and
(2) results from two studies on emergent constraint on ocean acidification in the Arctic Ocean that suggests that projections of Earth-System Models collectively underestimated the extent of future ocean acidification in the Arctic Ocean.
Continue reading ‘Stressors of the Arctic Ocean ecosystems: improved understanding of primary production and ocean acidification’Monitoring ocean acidification within State Borders: lessons from Washington State (USA)
Published 18 August 2021 Science ClosedTags: chemistry, field, laboratory, North Pacific, policy
The Washington State Department of Ecology conducted a large-scale ocean acidification (OA) study in greater Puget Sound to: (1) produce a marine carbon dioxide (CO2) system dataset capable of distinguishing between long-term anthropogenic changes and natural variability, (2) characterize how rivers and freshwater drive OA conditions in the region, and (3) understand the relative influence of cumulative anthropogenic forcing on regional OA conditions. Marine CO2 system data were collected monthly at 20 stations between October 2018 and February 2020. While additional data are still needed, the climate-level data collected thus far have uncovered novel insights into spatiotemporal distributions of and variability in the regional marine CO2 system, especially at low salinities in shallow, river-forced shelf regions. The data provide a strong foundation with which to continue monitoring OA conditions across the region. More importantly, this work represents the first successful long-term OA monitoring program undertaken at the state-level by a regulatory agency. Therefore, we offer the work described herein as a blueprint to help state and local scientists and environmental and natural resource managers develop, implement, and conduct long-term OA monitoring programs and studies in their own contexts and jurisdictions.
Continue reading ‘Monitoring ocean acidification within State Borders: lessons from Washington State (USA)’International and domestic leadership by U.S. States on ocean acidification
Published 18 August 2021 Science ClosedTags: policy
The role of symbiotic algae in the acclimatization of Oculina arbuscula to ocean acidification
Published 18 August 2021 Science ClosedTags: biological response, BRcommunity, calcification, chemistry, community composition, corals, field, laboratory, multiple factors, North Atlantic, otherprocess, photosynthesis, protists, temperature
Ocean acidification (OA) caused by CO2 emissions is projected to decrease seawater pH to 7.6 by 2100. Scleractinian corals are at risk because excess H+ in seawater binds to carbonate (CO3 2-), reducing its availability for CaCO3 skeletons. The energy demand for skeletal growth increases as pH decreases because corals must actively purge excess H+ from their seawater sourced calcifying fluid to maintain high calcification rates. In scleractinian corals it is hypothesized that photosynthesis by symbiotic algae is critical to meet this increased energy demand. To test this hypothesis, I conducted laboratory and field studies with Oculina arbuscula, a facultatively symbiotic coral common in the southeastern U.S.A., which exhibits resilience to seasonal fluctuations in pCO2 that drive pH to as low as 7.8 in the summer. In the lab, aposymbiotic and symbiotic O. arbuscula colonies were exposed to a pH of 8.0 or 7.6 for 51 days to test the role of the algal symbiosis in maintaining energy reserves, calcifying fluid pH, skeletal organic matrix and calcification rates during OA. To supplement this controlled laboratory experiment, I transplanted 20 coral colonies to a seafloor CO2 monitoring platform, exploiting the natural variation in pCO2 that occurs in Georgia coastal waters. The relationship between calcifying fluid pH and seawater pH was tested for in these samples using boron stable isotopes in coral skeletons. Contrary to the hypothesis, both aposymbiotic and symbiotic O. arbuscula colonies maintained similar calcification rates when exposed to OA. Upregulation of calcifying fluid pH, likely fueled by metabolic energy derived from heterotrophy, was the primary acclimatory mechanism detected. Symbiotic algae were associated with higher coral lipid reserves and denser skeletons, but neither of these variables were affected by seawater pH. Corals growing offshore maintained a consistent calcifying fluid pH in the face of seasonal fluctuations in seawater pH and other environmental variables such as temperature and turbidity. The results of my study provide valuable insight into how O. arbuscula has evolved to survive harsh conditions of seasonally low pH levels characteristic of southeastern U.S.A. coastal waters and the mechanisms that may contribute to its future resilience to increasing OA.
Continue reading ‘The role of symbiotic algae in the acclimatization of Oculina arbuscula to ocean acidification’Lunch & learn series – Ocean acidification in the Gulf of Maine: issue and solutions (text & video)
Published 18 August 2021 Presentations ClosedTags: resource, video/audio, webinar recording
We hope you enjoy this hour-long panel discussion on ocean and coastal acidification’s impact on scallops and softshell clams, methods of remediation, and future projections for the Gulf of Maine.
The talk was moderated by Dr. Libby Jewett, Director of the NOAA Ocean Acidification Program.
Panelists included, Dr. Samantha Siedlecki, University of Connecticut; Dr. Nichole Price, Bigelow Laboratory for Ocean Sciences; and Dr. Robert J Holmberg, Downeast Institute.
Continue reading ‘Lunch & learn series – Ocean acidification in the Gulf of Maine: issue and solutions (text & video)’A moment with the sea – communicating caring actions for the Baltic Sea
Published 18 August 2021 Art , Events ClosedTags: art exposition, resource
Baltic Sea Day Thursday August 26th 2021
Inspired by the Ocean Confessions by Pete Fung and Samein Shamshar and adapted in Tvärminne research station in Hanko by a multidisciplinary research group as part of the Baltic Sea Lab in the CreaTures Research project funded by the EU Horizon 2020 grant.
We invite you to participate in this action of caring for the Baltic Sea!
We want to enable a personal encounter with the sea by providing the participants to express their love, concerns, transgressions or fears for their local sea. The science we face daily is worrying and might easily lead us to feeling defeated and powerless. Through voicing our emotions, we can move into a space of gratitude, poetic, reflective, collectively caring. You can participate by attending the event at Hanaholmen or remotely by sending us your message to and for the Baltic Sea.
Participation at Hanaholmen 3 PM – 6 PM:
Professor of practise Julia Lohmann with her team presents her work and encourages us to show our engagement and care for the Baltic Sea. In this activity we will ask participants to spend a moment with the sea and share a thought with this body of water by writing it with chalk, a calcium based medium that acts as a token against ocean acidification. This writing will happen either directly on the rocks or on smaller stones and pieces of bark that can be placed by the shore. The reflections of care will be given to the sea.
As a symbolic act of care, the writings on the rock will be done using street chalk, which is made of calcium carbonate, and will enter the sea in the end. Calcium carbonate buffers the acidification of the sea caused by climate change.
Please sign up through this form.
Continue reading ‘A moment with the sea – communicating caring actions for the Baltic Sea’A proteomic analysis of the effect of ocean acidification on the haemocyte proteome of the South African abalone Haliotis midae
Published 17 August 2021 Science ClosedTags: biological response, laboratory, methods, mollusks, physiology, socio-economy, South Atlantic
Highlights
- 227 proteins were differentially expressed in response to ocean acidification conditions.
- Under OA conditions, H. midae underwent a metabolic shift to generate ATP via energy-efficient mechanisms.
- Haemocyte stabilisation and homeostasis in response to OA was reflected by up-regulation of oxidative stress and cytoskeletal proteins.
- An interplay between the stress and immune response was observed through up-regulation of proteins involved in protein synthesis and turnover, as well as intracellular signalling and transport.
Abstract
As a result of increasing CO2 emissions and the prevalence of global climate change, ocean acidification (OA) is becoming more pervasive, affecting many trophic levels, particularly those that rely on succinctly balanced ocean chemistry. This ultimately threatens community structures, as well as the future sustainability of the fishing/aquaculture industry. Understanding the molecular stress response of key organisms will aid in predicting their future survivability under changing environmental conditions. This study sought to elucidate the molecular stress response of the South African abalone, Haliotis midae, an understudied organism with high economic value, utilising a high throughput iTRAQ-based proteomics methodology. Adult abalone were exposed to control (pH 7.9) and experimental (pH 7.5) conditions for 12, 72 and 168 h, following which protein was isolated from sampled haemocytes and subsequently processed. iTRAQ-labelled peptides were analysed using mass spectrometry, while an array of bioinformatics tools was utilised for analysing the proteomic data. COG analysis identified “Cytoskeleton”, “Translation, ribosomal structure and biogenesis”, “Post-translational modification, protein turnover, chaperones”, and “Intracellular trafficking, secretion and vesicular transport” to be the most enriched functional classes, while statistical analysis identified a total of 33 up-regulated and 23 down-regulated effectors of OA stress in abalone. Several of the up-regulated proteins that were identified function in central metabolism (ENO1, PGK, DUOX1, GPD2), the stress/immune response (CAMKI, HSPA5/GRP78, MAPKI), and cytoskeleton, protein sorting and signal transduction (IQGAP1, MYO9B, TLN1, RDX, TCP-1/CCT, SNX6, CHMP1a, VPS13a). Protein-protein interactions were predicted using STRING DB, Cytoscape and Ingenuity Pathway Analysis, providing a model of the effects of OA on the H. midae haemocyte proteome. The data indicated that H. midae underwent a metabolic shift under OA conditions to utilize more energy-efficient mechanisms of ATP generation, while attempts at restoring haemocyte stabilisation and homeostasis were reflected by up-regulation of oxidative stress and cytoskeletal proteins. Our results support other molluscan studies that report a complex array of overlapping functions of both the stress and immune response systems. This interplay of the mounted stress and immune response is maintained and observed through the up-regulation of proteins involved in protein synthesis and turnover, as well as intracellular signalling and transport. The data presented in this study highlight the value of employing sensitive and robust -omics technologies for assessing the effects of changing environmental conditions on marine organisms.
Continue reading ‘A proteomic analysis of the effect of ocean acidification on the haemocyte proteome of the South African abalone Haliotis midae’Larval development in the Pacific oyster and the impacts of ocean acidification: differential genetic effects in wild and domesticated stocks
Published 17 August 2021 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, mortality, multiple factors, North Pacific, physiology, reproduction, temperature
The adaptive capacity of marine calcifiers to ocean acidification (OA) is a topic of great interest to evolutionary biologists and ecologists. Previous studies have provided evidence to suggest that larval resilience to high pCO2 seawater for these species is a trait with a genetic basis and variability in natural populations. To date, however, it remains unclear how the selective effects of OA occur within the context of complex genetic interactions underpinning larval development in many of the most vulnerable taxa. Here we evaluated phenotypic and genetic changes during larval development of Pacific oysters (Crassostrea gigas) reared in ambient (~ 400 µatm) and high (~ 1600 µatm) pCO2 conditions, both in domesticated and naturalized ‘wild’ oysters from the Pacific Northwest, USA. Using pooled DNA samples, we determined changes in allele frequencies across larval development, from early “D-stage” larvae to metamorphosed juveniles (spat), in both groups and environments. Domesticated larvae had ~ 26% fewer loci with changing allele frequencies across developmental stages and < 50% as many loci affected by acidified culture conditions, compared to larvae from wild brood stock. Functional enrichment analyses of genetic markers with significant changes in allele frequency revealed that the structure and function of cellular membranes were disproportionately affected by high pCO2 conditions in both groups. These results indicate the potential for a rapid adaptive response of oyster populations to OA conditions; however, underlying genetic changes associated with larval development differ between these wild and domesticated oyster stocks and influence their adaptive responses to OA conditions.
Continue reading ‘Larval development in the Pacific oyster and the impacts of ocean acidification: differential genetic effects in wild and domesticated stocks’The role of enhanced rock weathering deployment with agriculture in limiting future warming and protecting coral reefs
Published 17 August 2021 Science ClosedTags: biogeochemistry, chemistry, corals, globalmodeling, mitigation, modeling
Meeting the net-zero carbon emissions commitments of major economies by mid-century requires large-scale deployment of negative emission technologies (NETs). Terrestrial enhanced rock weathering on croplands (ERW) is a NET with co-benefits for agriculture, soils and ocean acidification that creates opportunities for generating income unaffected by diminishing carbon taxes as emissions approach net-zero. Here we show that ERW deployment with croplands to deliver net 2 Gt CO2 yr−1 removal approximately doubles the probability of meeting the Paris 1.5 °C target at 2100 from 23% to 42% in a high mitigation Representative Concentration Pathway 2.6 baseline climate. Carbon removal via carbon capture and storage (CCS) at the same rate had an equivalent effect. Co-deployment of ERW and CCS tripled the chances of meeting a 1.5 °C target (from 23% to 67%), and may be sufficient to reverse about one third of the surface ocean acidification effect caused by increases in atmospheric CO2 over the past 200 years. ERW increased the percentage of coral reefs above an aragonite saturation threshold of 3.5 from 16% to 39% at 2100, higher than CCS, highlighting a co-benefit for marine calcifying ecosystems. However, the degree of ocean state recovery in our simulations is highly uncertain and ERW deployment cannot substitute for near-term rapid CO2 emissions reductions.
Continue reading ‘The role of enhanced rock weathering deployment with agriculture in limiting future warming and protecting coral reefs’GOA-ON Webinar Series 2021: response of the Sydney rock oyster microbiome to rapidly warming and acidifying Australian estuaries (text & video)
Published 17 August 2021 Presentations ClosedTags: resource, video/audio, webinar recording
Webinar speaker: Dr. Elliot Scanes, Chancellor’s Research Fellow, Climate Change Cluster, The University of Technology, Sydney, Australia
Description:
Climate change is impacting ecosystems and organisms worldwide. Estuaries are diverse and important aquatic ecosystems; and yet until now we have lacked information on the response of estuaries to climate change. In this seminar I will present data from a twelve-year monitoring program, involving 6200 observations of 166 estuaries along ~1100 kilometers of the Australian coastline. Estuary temperatures increased by 2.16 C on average over 12 years, at a rate of 0.2 C/year, with waters acidifying at a rate of 0.09 pH units and freshening at 0.086 PSU/year. Lagoons and rivers are warming and acidifying at the fastest rate because of shallow average depths and limited oceanic exchange. The changes measured are an order of magnitude faster than predicted by global ocean and atmospheric models, indicating that existing global models may not be useful to predict change in estuaries. Estuaries are also home to diverse ecosystems and valuable economies supported by oysters. Oysters rely on bacterial communities forming a microbiome for their health and survival. Oysters are also vulnerable to disease and this is may be exacerbated by climate change in estuaries. We found that warming and acidification can shift the microbiome of Sydney rock oysters (Saccostrea glomerata), however, these effects can be ameliorated by selective breeding. We show that oyster genetic background may influence the microbiome under climate change and that future assisted evolution breeding programs could be used to enhance resilience in the oyster microbiome.
The GOA-ON webinar series has four sponsoring organizations:
(1) GOA-ON, the Global Ocean Acidification Observing Network,
(2) NOAA, the United States National Oceanic & Atmospheric Administration,
(3) IAEA OA-ICC, the International Atomic Energy Agency – Ocean Acidification International Coordination Centre, and
(4) IOC-UNESCO – the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization
Continue reading ‘GOA-ON Webinar Series 2021: response of the Sydney rock oyster microbiome to rapidly warming and acidifying Australian estuaries (text & video)’The role of soils in the regulation of ocean acidification
Published 13 August 2021 Science ClosedTags: chemistry
Soils play an important role in mediating chemical weathering reactions and carbon transfer from the land to the ocean. Proposals to increase the contribution of alkalinity to the oceans through ‘enhanced weathering’ as a means to help prevent climate change are gaining increasing attention. This would augment the existing connection between the biogeochemical function of soils and alkalinity levels in the ocean. The feasibility of enhanced weathering depends on the combined influence of what minerals are added to soils, the formation of secondary minerals in soils and the drainage regime, and the partial pressure of respired CO2 around the dissolving mineral. Increasing the alkalinity levels in the ocean through enhanced weathering could help to ameliorate the effects of ocean acidification in two ways. First, enhanced weathering would slightly elevate the pH of drainage waters, and the receiving coastal waters. The elevated pH would result in an increase in carbonate mineral saturation states, and a partial reversal in the effects of elevated CO2. Second, the increase in alkalinity would help to replenish the ocean’s buffering capacity by maintaining the ‘Revelle Factor’, making the oceans more resilient to further CO2 emissions. However, there is limited research on the downstream and oceanic impacts of enhanced weathering on which to base deployment decisions.
This article is part of the theme issue ‘The role of soils in delivering Nature’s Contributions to People’.
Continue reading ‘The role of soils in the regulation of ocean acidification’Warming, not CO2-acidified seawater, alters otolith development of juvenile Antarctic emerald rockcod (Trematomus bernacchii)
Published 13 August 2021 Science ClosedTags: Antarctic, biological response, fish, laboratory, morphology, multiple factors, physiology, temperature
The combustion of fossil fuels is currently causing rapid rates of ocean warming and acidification worldwide. Projected changes in these parameters have been repeatedly observed to stress the physiological limits and plasticity of many marine species from the molecular to organismal levels. High latitude oceans are among the fastest changing ecosystems; therefore, polar species are projected to be some of the most vulnerable to climate change. Antarctic species are particularly sensitive to environmental change, having evolved for millions of years under stable ocean conditions. Otoliths, calcified structures found in a fish’s inner ear used to sense movement and direction, have been shown to be affected by both warming and CO2-acidified seawater in temperate and tropical fishes but there is no work to date on Antarctic fishes. In this study, juvenile emerald rockcod (Trematomus bernacchii) were exposed to projected seawater warming and CO2-acidification for the year 2100 over 28 days. Sagittal otoliths were analyzed for changes in area, perimeter, length, width and shape. We found ocean warming increased the growth rate of otoliths, while CO2-acidified seawater and the interaction of warming and acidification did not have an effect on otolith development. Elevated temperature also altered the shape of otoliths. If otolith development is altered under future warming scenarios, sensory functions such as hearing, orientation, and movement may potentially be impaired. Changes in these basic somatic abilities could have broad implications for the general capabilities and ecology of early life stages of Antarctic fishes.
Continue reading ‘Warming, not CO2-acidified seawater, alters otolith development of juvenile Antarctic emerald rockcod (Trematomus bernacchii)’Climate change negates positive CO2 effects on marine species biomass and productivity by altering the strength and direction of trophic interactions
Published 13 August 2021 Science ClosedTags: fish, mesocosms, methods, performance, primary production
Highlights
- We need more insight into how future food webs might be altered under climate change
- We used empirical data of species interactions from multi-species mesocosms to model trophic interaction strengths within the food web
- We separate direct from indirect species interactions, something which is seldom considered in climate studies
- We show that warming is an overwhelming climate stressor that alters trophic interactions in both negative and positive ways
- Ocean acidification boosted primary productivity which enabled energy to flow upward to higher trophic levels
- We further show that the direct effects of warming are more severe than its indirect effects
Abstract
One of the biggest challenges in more accurately forecasting the effects of climate change on future food web dynamics relates to how climate change affects multi-trophic species interactions, particularly when multiple interacting stressors are considered. Using a dynamic food web model, we investigate the individual and combined effect of ocean warming and acidification on changes in trophic interaction strengths (both direct and indirect) and the consequent effects on biomass structure of food web functional groups. To do this, we mimicked a species-rich multi-trophic-level temperate shallow-water rocky reef food web and integrated empirical data from mesocosm experiments on altered species interactions under warming and acidification, into food-web models. We show that a low number of strong temperature-driven changes in direct trophic interactions (feeding and competition) will largely determine the magnitude of biomass change (either increase or decrease) of high-order consumers, with increasing consumer biomass suppressing that of prey species. Ocean acidification, in contrast, alters a large number of weak indirect interactions (e.g. cascading effects of increased or decreased abundances of other groups), enabling a large increase in consumer and prey biomass. The positive effects of ocean acidification are driven by boosted primary productivity, with energy flowing up to higher trophic levels. We show that warming is a much stronger driver of positive as well as negative modifications of species biomass compared to ocean acidification. Warming affects a much smaller number of existing trophic interactions, though, with direct consumer-resource effects being more important than indirect effects. We conclude that the functional role of consumers in future food webs will be largely regulated by alterations in the strength of direct trophic interactions under ocean warming, with ensuing effects on the biomass structure of marine food webs.
Continue reading ‘Climate change negates positive CO2 effects on marine species biomass and productivity by altering the strength and direction of trophic interactions’Sea surface CO2 fugacity in the southwestern South Atlantic Ocean: an evaluation based on satellite-derived images
Published 13 August 2021 Science ClosedTags: chemistry, field, South Atlantic
The South Atlantic Ocean is historically less sampled than the North Atlantic Ocean. Recent efforts have improved our understanding of the carbonate system variable distribution, mainly on sea surface CO2 fugacity (fCO2). However, these studies have been regionally and temporally restricted. Hence, in this research we developed seasonal algorithms of sea surface fCO2 to investigate the CO2 dynamics along the southwestern South Atlantic Ocean during spring-summer and fall-winter periods. The studied region includes the continental shelf areas of the Abrolhos-Campos Region (an area under the influence of central water upwelling), the South Brazil Bight (a large embayment affected by the mesoscale variability in a westward boundary current), the Southern Brazilian Shelf (a coastal zone influenced by freshwater discharge from continent and water mass entrainment), and offshore waters in the open ocean domain of the southwestern South Atlantic Ocean. Monthly satellite images of sea surface temperature, salinity, and chlorophyll-a, which were concomitantly available from August 2011 to June 2015, were used to reconstruct and evaluate the sea surface fCO2 seasonal field. The predicted fields of sea surface fCO2 enabled an investigation of the main drivers that change this variable over the distinct biogeochemical provinces in the region. As expected, the sea surface temperature was the main driver of seasonal changes in sea surface fCO2, but total dissolved inorganic carbon (DIC) and total alkalinity changes were also relevant, mainly in the biogeochemical provinces under the influence of continental freshwater input or central water upwelling. The latter can play an unpredictable role in CO2 dynamics due to nutrient- and DIC-rich water transport close to the surface. Finally, the use of satellite-derived images is a powerful tool to increase biogeochemical knowledge of relatively undersampled ocean regions, while the development of seasonal sea surface fCO2 algorithms allows a better spatiotemporal comprehension of the CO2 distribution, dynamics, and drivers in the southwestern South Atlantic Ocean – a key region for improving the understanding of the global carbon cycle.
Continue reading ‘Sea surface CO2 fugacity in the southwestern South Atlantic Ocean: an evaluation based on satellite-derived images’Ocean acidification: what happens to coral reefs? (text & video)
Published 13 August 2021 Presentations ClosedTags: film, resource, video/audio
As the ocean acidifies, marine life comes under threat. Bubble sites in Papua New Guinea act as a time machine, allowing us to see the future we’re heading towards. How can we avert the worst effects of ocean acidification?
Learn more about ocean acidification in my film Sea of Life: https://www.seaoflifemovie.com/
Continue reading ‘Ocean acidification: what happens to coral reefs? (text & video)’
