Ocean acidification (OA) is a major challenge for marine environmental governance, and one that has given rise to increasing concern as scientific knowledge of the problem and its impacts continues to grow. This chapter thus explores governance arrangements for strengthening marine ecosystem health and resilience and the extent to which they incorporate responses to OA. There is a complex suite of existing governance arrangements for strengthening marine ecosystem resilience that can be harnessed to help vulnerable aquatic systems as the oceans acidify. However, this chapter also demonstrates that management for OA is, at best, a marginal consideration in existing marine biodiversity conservation regimes, despite the significant threat that OA poses to vulnerable aquatic systems. The chapter therefore highlights a significant potential role for marine ecosystem governance arrangements in promoting meaningful steps towards integrated OA and marine conservation management across multiple governance scales. The chapter briefly summarizes OA science and the socio-ecological impacts of acidification in the oceans, before highlighting the role of strengthening marine ecosystem health and resilience in helping vulnerable aquatic systems cope with OA. The chapter also explores relevant governance arrangements and how they address OA at multilateral, regional and in a limited number of domestic jurisdictions, and underlines key governance opportunities and gaps in existing governance frameworks.
Continue reading ‘Chapter 8 – Responding to ocean acidification by strengthening marine ecosystem health and resilience’Archive Page 53
Chapter 8 – Responding to ocean acidification by strengthening marine ecosystem health and resilience
Published 31 December 2024 Science ClosedTags: mitigation, policy, review
Advisory opinion on the request for an advisory opinion submitted by the comm’n of small island states on climate change and int’l law (I.T.L.O.S.)
Published 31 December 2024 Science ClosedTags: policy
On May 21, 2024, the International Tribunal for the Law of the Sea (the Tribunal) delivered a unanimous advisory opinion on the Request submitted to the Tribunal by the Commission of Small Island States on Climate Change and International Law. This was the first advisory opinion on climate change obligations issued by an international judicial body, and the first of three anticipated advisory opinions on climate change obligations from international judicial bodies. The request had been submitted on December 12, 2022 by the Commission of Small Island States on Climate Change and International Law (COSIS). Two questions on obligations of states parties under the United Nations Convention on the Law of the Sea (UNCLOS) were posed in the request: (1) what are the specific obligations to prevent, reduce, and control pollution of the marine environment in relation to the deleterious effects that result, or are likely to result, from climate change and ocean acidification, which are caused by anthropogenic greenhouse gas (GHG) emissions into the atmosphere; and (2) what are the specific obligations to protect and preserve the marine environment in relation to climate change impacts and ocean acidification. A total of 34 states parties to UNCLOS and nine intergovernmental organizations submitted statements, and 33 states parties and four intergovernmental organizations made statements during the oral proceedings.
Continue reading ‘Advisory opinion on the request for an advisory opinion submitted by the comm’n of small island states on climate change and int’l law (I.T.L.O.S.)’Environmental determinants of reef fish community structure in Sempu Strait, East Java, Indonesia
Published 31 December 2024 Science ClosedTags: chemistry, community composition, field, fish, Indian, otherprocess
The Rumah Apung located in Sempu Strait, Malang District, East Java, Indonesia, is home to diverse coral reef ecosystems that provide vital ecological services and support local livelihoods. However, these ecosystems face significant threats from both natural environmental changes and anthropogenic activities. Understanding how environmental factors influence reef fish communities is critical to inform effective conservation strategies. This study investigated the influence of environmental factors on the community structure of coral reef fish in the Sempu Strait waters, East Java, using Underwater Visual Census (UVC) and Principal Component Analysis (PCA). Conducted from August 2023 to May 2024 at the Sempu Strait Floating House Station, this study aimed to assess the impact of water quality, substrate type, and food availability on the diversity and abundance of coral reef fish. The main results revealed a significant correlation between the community structure of coral reef fish and environmental variables such as water clarity, salinity (r=0.65, p<0.01), pH (r=0.55, p<0.05), dissolved oxygen (r=0.70, p<0.01), and sediment type. Seasonal variations significantly affected water quality, with cold nutrient-rich water during the east monsoon increasing fish biomass by about 30%. Human activities, especially recreational diving and fishing activities, were correlated with a 20% decline in coral reef fish populations, highlighting the anthropogenic pressure on this ecosystem. PCA provides insight into the complex interdependencies within coral reef ecosystems, illustrating how multiple environmental factors combine to influence reef fish dynamics. The study concludes that effective management and conservation strategies,such as establishing marine protected areas, implementing community-based monitoring programs, and promoting sustainable tourism practices, are essential, supported by regular environmental monitoring, are essential to maintain the biodiversity and ecological integrity of coral reefs in the Sempu Strait. These strategies should address both natural environmental changes and anthropogenic impacts to mitigate their adverse effects on coral reef ecosystem conditions.
Continue reading ‘Environmental determinants of reef fish community structure in Sempu Strait, East Java, Indonesia’Arctic Ocean acidification and carbonate undersaturation enhanced by coastal permafrost erosion
Published 31 December 2024 Science ClosedTags: Arctic, biogeochemistry, modeling, regionalmodeling
Increasing atmospheric CO2 drives ocean acidification, with some of the fastest rates observed on Arctic shelves. Lowest pH levels occur near the coasts due to the additional effects of land-derived carbon sources. However, the impact of anthropogenic climate change on seawater acidity mediated by increasing permafrost thaw and coastal erosion remains unknown. Here, we find that the increase in organic matter release by coastal permafrost erosion over the 20th century enhances the interannual variability of seawater pH in Arctic near-shore areas. As a consequence, carbonate undersaturation events, stressing marine ecosystems, become more frequent, intense, and longer-lasting. We account for synergistic effects of anthropogenic climate change by combining increasing atmospheric CO2 levels and coastal erosion rates, utilizing a novel global model with high-resolution grid refinement towards coastal regions and improved process representation of shelf-specific carbon dynamics. By considering the role of coastal permafrost erosion, we conclude that critical Arctic Ocean acidification states will emerge earlier than simulated by the current generation of Earth system models. Our results emphasize the importance of understanding permafrost-ocean interactions and their increasing impact on marine ecosystems, especially in the rapidly changing Arctic region.
Continue reading ‘Arctic Ocean acidification and carbonate undersaturation enhanced by coastal permafrost erosion’Local effects of Sargassum beds on the seawater carbonate system and plankton community
Published 30 December 2024 Science ClosedTags: biological response, BRcommunity, chemistry, crustaceans, field, mitigation, North Pacific, phanerogams, phytoplankton, zooplankton
Highlights
- The ecological effect of the sargassum beds depends on seaweed biomass.
- The biomass of the sargassum beds in Weizhou Island reached its peak in spring.
- Sargassum beds significantly influenced the carbonate system and DOC pool in spring.
- Sargassum beds is more likely to alter phytoplankton communities than zooplankton.
Abstract
Sargassum beds are recognized as important habitats for fostering species diversity and capturing blue carbon, exerting significant influence on seawater chemistry and planktonic communities. However, there is still much to uncover about the interactions between these biogenic habitats and seawater chemistry, as well as their impact on plankton communities in the water column. To address this gap, we conducted a study on the functions of natural Sargassum beds in various seasons around the northern part of Weizhou Island in the South China Sea. Our research involved quantifying carbonate chemistry, carbon stock potential, and seawater plankton communities in two distinct areas: the core area in the interior regions of the seaweed beds and the non-core areas at its periphery or external. Our findings revealed an estimated 3.7 km2 of benthic Sargassum, with an overall biomass of 21.2 Gg km−2, reaching its peak productivity in spring, equivalent to 1.14 Pg C km−2. Notably, during spring, the seaweed beds significantly influenced the exchange of CO2 at the air-sea interface, leading to reduced pCO2 (41 μatm) in the core area compared to the non-core area (p < 0.05), thus enhancing the local carbon sequestration capacity. Additionally, we observed significant regional differences in the concentration of dissolved organic carbon (DOC) only during the spring season, indicating the capacity of Sargassum to alter the DOC pool around its habitat. We anticipate that seaweed deposition will become a more frequent occurrence towards the end of the growth period, with increasing fragments facilitating a transition towards phytoplankton-dominated marine ecosystems. Furthermore, the fixation of extra CO2 by seaweed may lead to a pH increase, providing a refuge for copepods from ocean acidification. In summary, our observations suggest that the Sargassum beds plays a substantial role in nearshore carbon cycling and ecological impact, surpassing previous documentation.
Continue reading ‘Local effects of Sargassum beds on the seawater carbonate system and plankton community’Regional relationship between total alkalinity and salinity in the surface waters of the western South Atlantic margin
Published 30 December 2024 Science ClosedTags: chemistry, field, modeling, regionalmodeling, South Atlantic
Highlights
- Surface AT and SSS patterns show a decreasing pattern from north to south along the southwestern South Atlantic margin.
- The relationship found between surface AT and SSS reveals that salinity explains ∼ 80 % of AT variability.
- The estimated AT values reflect both current-dominated and freshwater mixing processes along the southwestern SAO margin.
Abstract
We examined the surface total alkalinity (AT) and salinity (SSS) distributions and their relationship along the southwestern South Atlantic Ocean margin off the Brazilian coast. In situ hydrographic data from shelf and slope stations were measured during three oceanographic cruises in October 2014 (austral spring), April 2018 (austral autumn) and June 2019 (austral winter). The northern portion of the study area lies within the Brazil Current domain, transporting warm and salty Tropical Water, while further south the Subtropical Shelf Water and the freshwater plume derived from the Patos Lagoon and Plata River influence the temperature, salinity, and AT distribution. The present study aimed to determine the relationship between AT and SSS to establish a model for reconstructing a surface time series for the marine carbonate system in the undersampled region of the subtropical southwestern South Atlantic Ocean margin. The AT – SSS relationship showed a significant positive linear relationship (r2=0.76), reflecting both current-dominated (i.e., outer and northernmost stations) and freshwater mixing processes (i.e., inner and southernmost stations and continental inputs). The observed AT values were well correlated with the reported ranges for the tropical and subtropical South Atlantic Ocean, and the predicted AT obtained from the Global Ocean Data Analysis Project and the World Ocean Database 2013 SSS data confirmed lower AT in shelf waters under the influence of continental inputs, which increased towards the outer shelf and slope. Finally, the newly proposed regional AT – SSS relationship improves previous linear regressions for the southwestern Atlantic Ocean margin.
Continue reading ‘Regional relationship between total alkalinity and salinity in the surface waters of the western South Atlantic margin’The effect of carbonic anhydrase on foraminiferal Mg/Ca
Published 30 December 2024 Science ClosedTags: biological response, laboratory, morphology, physiology, protists
Marine biogenic calcium carbonate production plays a role in the exchange of CO2 between ocean and atmosphere. The effect of increased CO2 on calcification and on the resulting chemistry of shells and skeletons, however, is only partly understood. Foraminifera are among the main marine CaCO3 producers and the controls on element partitioning and isotope fractionation is the subject of many recent investigations. The enzyme carbonic anhydrase (CA) was, for example, shown to be vital for CaCO3 deposition in benthic foraminifera and indicates their ability to manipulate their intracellular inorganic carbon chemistry. Here, we tested whether CA affects the partitioning of Na, Mg and Sr in the perforate, large benthic, symbiont-bearing foraminifer Amphistegina lessonii by addition of the inhibitor acetazolamide (AZ). The effect of dissolved CO2 on the effect of CA on element partitioning was also determined using a culturing setup with controlled atmospheric carbon dioxide levels (400–1,600 ppm). Results show that inhibition by AZ reduces calcification greatly and that CO2 has a small, but positive effect on the amount of calcite formed during the incubations. Furthermore, the inhibition of CA activity has a positive effect on element partitioning, most notably Mg. This may be explained by a (n indirect) coupling of inorganic carbon uptake and inward calcium ion pumping.
Continue reading ‘The effect of carbonic anhydrase on foraminiferal Mg/Ca’Organic alkalinity distributions, characteristics, and application to carbonate system calculations in estuarine and coastal systems
Published 27 December 2024 Science ClosedTags: chemistry, field, North Atlantic
The capacity of aquatic systems to buffer acidification depends on the sum contributions of various chemical species to total alkalinity (TA). Major TA contributors are inorganic, with carbonate and bicarbonate considered the most important. However, growing evidence shows that many rivers, estuaries, and coastal waters contain dissolved organic molecules with charge sites that create organic alkalinity (OrgAlk). This study describes the first comparison of (1) OrgAlk distributions and (2) acid–base properties in contrasting estuary-plume systems: the Pleasant (Maine, USA) and the St. John (New Brunswick, CA). The substantial concentrations of OrgAlk in each estuary were sometimes not conservative with salinity and typically associated with very low pH. Two approaches to OrgAlk measurement showed consistent differences, indicating acid–base characteristics inconsistent with the TA definition. The OrgAlk fraction of TA ranged from 78% at low salinity to less than 0.4% in the coastal ocean endmember. Modeling of titration data identified three groups of organic charge sites, with mean acid–base dissociation constants (pKa) of 4.2 (± 0.5), 5.9 (± 0.7) and 8.5 (± 0.2). These represented 21% (± 9%), 8% (± 5%), and 71% (± 11%) of titrated organic charge groups. Including OrgAlk, pKa, and titrated organic charge groups in carbonate system calculations improved estimates of pH. However, low and medium salinity, organic-rich samples demonstrated persistent offsets in calculated pH, even using dissolved inorganic carbon and CO2 partial pressure as inputs. These offsets show the ongoing challenge of carbonate system intercomparisons in organic rich systems whereby new techniques and further investigations are needed to fully account for OrgAlk in TA titrations.
Continue reading ‘Organic alkalinity distributions, characteristics, and application to carbonate system calculations in estuarine and coastal systems’Ocean warming and acidification alter calcification and innate immune system gene expression in juvenile American lobsters, Homarus americanus
Published 27 December 2024 Science ClosedTags: biological response, crustaceans, laboratory, molecular biology, multiple factors, North Atlantic, temperature
Highlights
- Ocean warming and acidification affect gene expression in juvenile lobsters.
- De novo trascriptome used to assess gene expression and functional enrichment.
- Calcification and cuticle genes increased expression with warming and acidification.
- Innate immune system genes trended toward downregulation.
- Lobsters may be more vulnerable to injury or disease due to climate change.
Abstract
The Gulf of Maine, home to American lobster, Homarus americanus, is experiencing rapid ocean warming (OW) and acidification (OA) due to climate change. While some studies have investigated the effects of either ocean acidification (OA) or warming (OW) on lobsters, few explore the interaction of these stressors, particularly on gene expression. We evaluated the effects of OA and OW on early benthic juvenile lobster transcriptomics using RNA sequencing and RT-qPCR through two distinct aquarium experiments. Lobsters were reared under OW/OA conditions aligned with values predicted for 2100: decrease in pH by 0.3–0.4 units; mean sea surface warming of 2.89 °C. RNA was isolated from carapace hypodermal tissue in both experiments. The multi-stressor treatment in the RNAseq experiment had the greatest differential expression. Genes of interest pertaining to calcification and cuticle development were primarily downregulated under high temperature but upregulated under acidified and multi-stressor conditions. In the RT-qPCR experiment, crustin alone was significantly downregulated and only under the most extreme multi-stressor treatment. This gene along with the prophenoloxidase activating enzyme had expression that trended toward downregulation across all treatments, suggesting a possible correlation to immune suppression. Expression profiles for crustin and the calcification gene, carbonic anhydrase differed across treatments based on molt cycle timing, indicating that stressor impacts may vary depending on the molt cycle phase. Elevated temperature had a greater effect on the expression of calcification and cuticle development genes, though the direction of expression reversed with multiple stressors. These results indicate the impacts of OW and OA on early benthic juvenile lobsters are complex, possibly synergistic, vary with molt cycle, and potentially interfere with normal cuticle development, which may increase susceptibility to injury or disease.
Continue reading ‘Ocean warming and acidification alter calcification and innate immune system gene expression in juvenile American lobsters, Homarus americanus’Characteristics of dissolved inorganic carbon (DIC) in the western coast of the Taiwan Strait using a shipboard measurement
Published 27 December 2024 Science ClosedTags: chemistry, field, North Pacific
An online dissolved inorganic carbon (DIC) monitoring system was produced to achieve high spatial and temporal resolution in DIC data from the western Taiwan Strait (WTS) during the summer. Surface seawater DIC, salinity, dissolved organic carbon (DOC), Chl-a, and NO3− samples were collected, as well as the vertical profiles of DIC, to understand DIC variations in the WTS. The results showed that the range of DIC levels in the surface seawater from the WTS was from 1.68 to 2.21 mmol/L (Mmol), with an average of 1.93 ± 0.19 Mmol, which was consistent with the sampling results using titration determination, with an average of 1.98 ± 0.12 Mmol. A high correlation (R2 = 0.96) was presented between the online monitoring and sampling detection of DIC, indicating that DIC could be measured with high accuracy using the online monitoring system. The spatial distribution of DIC was similar to that of salinity, but it was different from that of DOC and Chl-a. The DIC concentration positively correlated with salinity (R2 = 0.51) and presented a negative correlation (R2 = 0.92) with seawater temperature. However, the surface seawater DIC was almost independent from DOC and Chl-a in the observation sea areas. The DIC levels first increased and then decreased with the depth, with the highest DIC concentration occurring in the subsurface water at about 10 m, which was similar to the profiles of salinity and Chl-a in the northern and southern areas of the WTS. The profiles of DIC, salinity, NO3−, and Chl-a were almost independent from the water depth in the central WST. This indicated that seawater DIC in the WTS was mainly affected by seawater temperature, salinity, and the vertical mixing of sea water, but it was less impacted by TOC and Chl-a.
Continue reading ‘Characteristics of dissolved inorganic carbon (DIC) in the western coast of the Taiwan Strait using a shipboard measurement’Development of a high-resolution ocean ensemble future projection dataset for the North Pacific incorporating simple biogeochemical processes
Published 27 December 2024 Science ClosedTags: biogeochemistry, modeling, North Pacific, regionalmodeling
In this study, we developed a new version of the future ocean regional projection dataset in the North Pacific (FORP-NP10) by performing an ensemble of historical and multi-scenario future projection simulations from 1960 to 2100 using a high-resolution ocean downscaling model system driven by surface forcings based on the atmospheric data of the Coupled Model Intercomparison Project (Phase 5). This version is characterized by the inclusion of simple biogeochemical processes within the simulations of the multi-case (four forcing cases) and multi-future projection scenarios (representative concentration pathway 2.6 and 8.5) using a mesoscale eddy-resolving (approximately 10 km) horizontal resolution. The dataset reasonably represented the main biogeochemical properties in the North Pacific and around Japan, such as surface CO2 flux, pH, subsurface oxygen, surface nitrate, and chlorophyll, as well as the ocean physics of the regions, including the mesoscale/frontal structures of the Kuroshio, Kuroshio Extension, and mixed layer depth. We assessed the bias tendencies and structures of these properties by comparing them with observational reference data and the low-resolution model results. Our ensemble dataset consistently projected future upper-ocean warming, acidification, deoxygenation, and changes in nutrient and primary production in the twenty-first century (reported as global analyses in recent reports of the Intergovernmental Panel on Climate Change) in the regions surrounding Japan, revealing that the future changes exhibited spatial contrasts or varying tendencies in the regions.
Continue reading ‘Development of a high-resolution ocean ensemble future projection dataset for the North Pacific incorporating simple biogeochemical processes’Some fish and crab may shift further north in Alaskan waters than previously predicted
Published 26 December 2024 Press releases ClosedThe eastern Bering Sea is a highly productive marine ecosystem, supporting more than 40 percent of the annual commercial fisheries landings by volume in the United States. Scientists have developed new models that predict more extreme changes in this ecosystem by the end of the century. They anticipate larger summer northward shifts and changes (both increases and decreases) in the area occupied by important commercial crab and fish species.
Specifically, the majority of models estimate changes in the center of distribution for several commercially important species. They predict that most species’ summer distributions will shift north by between 50 and 200 kilometers by 2080-2089. Scientists also project:
- Large declines in the amount of area occupied by red king crab and snow crab and potentially northern rock sole in the summer months.
- A substantial increase in the area occupied by arrowtooth flounder, a key predator of walleye pollock.
- Declines in probability of occurrence for most species in areas with low pH and oxygen concentration.
These changes are altogether more extreme than previous species distribution model projections, which accounted for fewer climate effects.
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Maps of two metrics of environmental novelty in the Bering Sea survey region for average temperature, pH, and oxygen conditions during 2040-2059 and 2080-2099, under each climate scenario (SSP 1-2.6 & SSP 5-8.5) and ESM (CESM, GFDL, & MIROC). Areas in gray are those for which temperature, pH, and oxygen are within the range of the average hindcasted conditions between 1995 and 2015. Areas in red / orange are those for which temperature, pH, and/or oxygen lie completely outside of the set of average conditions observed between 1995 and 2015. Areas in blue / green are those for which temperature, pH, and oxygen lie inside the range of hindcasted conditions, but represent novel combinations of these covariates. For both metrics, brighter colors indicate more novel conditions.
New and Better Models to Anticipate Ocean Changes
Scientists built species distribution models for eight common and/or commercially important species of groundfish and crabs in the eastern Bering Sea (adults and juveniles). These include walleye pollock, Pacific halibut, Pacific cod, arrowtooth flounder, northern rock sole, yellowfin sole, snow crab, and red king crab.
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To date, most studies projecting marine species distributions rely principally on temperature and static habitat characteristics such as depth. This can potentially lead to significant underestimation of species vulnerability to climate change.
However, for this study, ecologists combined 40 years of scientific surveys with a high-resolution oceanographic model. This model was adapted to the eastern Bering Sea by scientists at NOAA’s Alaska Fisheries Science Center as part of the Alaska Climate Integrated Modeling project. They examined the effects of bottom temperature. But they also incorporated information on oxygen, pH, and a regional climate index (the extent of the eastern Bering Sea “cold pool”). They considered all of these factors to produce a range of different climate projections through the end of the century. Model projections also anticipated warming under both low and high greenhouse gas emission scenarios.
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Oxygen and pH
The oceans absorb about 30 percent of global carbon dioxide emissions, and warmer water holds less oxygen. Climate change is also leading to the acidification of deoxygenation of much of the global ocean. All animals need oxygen to survive, and many species are expected to shift towards deeper, cooler waters to keep up with climate change. Lower dissolved oxygen content at depth may constrain their ability to do so. Reduced pH in water has the potential to impair organisms by changing their metabolism and physiological function. For crabs and other calcifying organisms, it can decrease calcification and shell formation rates.
Yet, few studies projecting future changes in species distributions integrate the effects of oxygen and pH. In many cases, these variables are not available to modelers, but recent advances in oceanographic modeling have made it possible to include their effects.
The authors found that the estimated effects of oxygen and pH were largely consistent among species. Where environmental oxygen and pH levels were lower, groundfish and crabs were less likely to be observed in scientific surveys. However, they also found the effects of oxygen and pH were difficult to disentangle using survey data, so they modeled their effects using separate models. In projecting future climate-driven changes in species distributions, they gave more say to models that did a better job reproducing past trends.
Where Scientists Hope to Go Next with this Research
These results build on—and in many cases agree with—previous distribution modeling efforts in the Bering Sea. However, they demonstrate that models that account for factors beyond temperature can result in more pronounced range shift projections.
“What’s really exciting about this research is we are now able to construct long-term species range forecasts, which incorporate a wider array of climate impacts,” said Kirstin Holsman, co-author and research fishery biologist, Alaska Fisheries Science Center.
In future work, species distribution models may be used to improve the representation of species interactions in multispecies stock assessment models. Scientists also hope to be able to produce short-term forecasts and long-term projections that incorporate a better understanding of predator-prey overlap.
Continue reading ‘Some fish and crab may shift further north in Alaskan waters than previously predicted’Climate covariate choice and uncertainty in projecting species range shifts: a case study in the Eastern Bering Sea
Published 26 December 2024 Science ClosedTags: Arctic, biological response, crustaceans, field, fish, fisheries, modeling, multiple factors, oxygen, regionalmodeling, temperature
Species distribution models (SDMs) are critical to the adaptive management of fisheries under climate change. While many approaches projecting marine species range shifts have incorporated the effects of temperature on movement, there is a need to incorporate a wider suite of ecologically relevant predictors as temperature-based SDMs can considerably under- or over-estimate the rate of species responses to climate shocks. As a subarctic ecosystem at the sea ice margin, the Eastern Bering Sea (EBS) is warming faster than much of the global ocean, resulting in the rapid redistribution of key fishery and subsistence resources. To support long-term planning and adaptation, we combine 40 years of scientific surveys with a high-resolution oceanographic model to examine the effects of bottom temperature, oxygen, pH and a regional climate index (the extent of the EBS ‘cold pool’) on range projections through the end of the century. We use multimodel inference to partition uncertainty among earth systems models, climate scenarios and distribution model parameterizations for several ecologically and economically important EBS groundfish and crabs. Covariate choice is the primary source of uncertainty for most species, with models that account for spatial responses to the cold pool performing better and suggesting more extensive northward movements than alternative models. Models suggest declines in the probability of occurrence at low pH and oxygen concentrations for most species. We project shifts that are directionally consistent with, yet larger than those previously estimated for most species, suggesting that accounting for large-scale climate variability in species distribution models may substantially alter range projections.
Continue reading ‘Climate covariate choice and uncertainty in projecting species range shifts: a case study in the Eastern Bering Sea’Short-term responses of native (Perna viridis, Linnaeus 1758) and non-native (Mytella strigata, Hanley 1843) mussels to independent and combined effects of lowered pH level and elevated temperature
Published 26 December 2024 Science ClosedTags: adaptation, biological response, BRcommunity, calcification, laboratory, mollusks, mortality, multiple factors, otherprocess, physiology, temperature
Changes in environmental conditions can influence the success of marine biological invasions. This study assessed the independent and combined acute short-term effects of increased temperature (OW) and lowered pH (OA) simulating future ocean conditions on a native, Perna viridis, and non-native, Mytella strigata, mussel species. There were four treatment combinations: Future (combination of ocean warming and ocean acidification), Ambient conditions, ocean acidification (OA), and ocean warming (OW). Survival and byssus thread regeneration in all treatments were measured daily for 7 days, while net calcification rate was calculated from the start and end of the experiment. Net calcification rate (NCR) was lowest under OA treatment. Likewise the low total alkalinity at the start of the experiment under OA suggests that the mussels experienced greater physiological stress. The higher survival rate of green mussels and the increase in the byssus regeneration rate over time in all treatments demonstrated that it can acclimate better to acute short-term temperature and pH stress. The very low survival of M. strigata in OA compared to other treatments indicates its high sensitivity to low pH stress. However, surviving charru individuals maintained high byssus thread regeneration in all treatments. Overall, results suggest that M. strigata may not displace the native green mussels’, P. viridis, higher tolerance to acute short-term exposure to elevated temperatures and low pH, but can co-exist in lower densities. This is the first study to compare the short-term physiological responses of a sympatric non-native and native mussel species under experimentally induced stress conditions. Longer-term studies on the population dynamics of these species are essential to assess the potential success of these species under changing and variable environmental conditions.
Continue reading ‘Short-term responses of native (Perna viridis, Linnaeus 1758) and non-native (Mytella strigata, Hanley 1843) mussels to independent and combined effects of lowered pH level and elevated temperature’Why ocean acidification is called climate change’s evil twin
Published 25 December 2024 Media coverage ClosedOcean acidification is an urgent environmental challenge caused by rising atmospheric carbon dioxide (CO2) levels, mainly due to human activities. It involves a continuous decrease in the pH of ocean water, with profound implications for marine ecosystems and the communities that rely on them. When CO2 is absorbed by seawater, it reacts to form carbonic acid, resulting in lower pH levels and increased acidity in the oceans.
Since the Industrial Revolution – a period of major technological and economic change that transformed society from an agrarian economy to one based on industry and manufacturing – ocean pH has dropped from about 8.19 to approximately 8.05, representing a 30 per cent increase in acidity. Although this change may seem minor, it can significantly affect marine life.
The primary concern regarding ocean acidification lies in its effects on marine organisms, especially those that depend on calcium carbonate to form their shells and skeletons. They include corals, molluscs and certain plankton species. Ocean acidity decreases the availability of carbonate ions, which is crucial for these organisms, making it increasingly difficult for them to construct and maintain their structures. This physiological stress from lower pH levels can disrupt marine species’ growth, reproduction and overall health.
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Ocean acidification has been referred to as “climate change’s evil twin” because it intensifies many of the same issues associated with global warming and presents unique challenges. While climate change leads to rising ocean temperatures and altered weather patterns, ocean acidification directly threatens marine chemistry and biology.
The pace of acidification is alarming, estimated to be about 100 times faster than any natural changes over the past 650,000 years, indicating that human activities are dramatically altering ocean ecosystems at an unprecedented speed. These changes threaten individual species and entire food webs.
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The main drivers of ocean acidification are anthropogenic CO2 emissions from burning fossil fuels, deforestation, and industrial processes. Oceans have absorbed approximately one-third of the CO2 released into the atmosphere since the Industrial Revolution.
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Different regions of the ocean experience varying levels of acidification due to factors such as geographical location, water temperature and local environmental conditions. Coastal areas often face higher rates of acidification compared to open ocean regions because they are influenced by freshwater runoff that carries nutrients and pollutants from land. This runoff can lead to localised increases in CO2 levels and subsequent acidification.
Warmer waters hold less dissolved oxygen and can amplify the effects of acidification on marine life. Regions with high biological activity, like upwelling zones where nutrient-rich waters rise to the surface, may also experience more pronounced effects due to natural CO2 release from decomposing organic matter. These regional differences underscore the complexity of ocean acidification as a global issue. In contrast, some areas may adapt better than others. However, the overall trend is troubling for marine ecosystems worldwide.
Efforts to combat ocean acidification include mitigation strategies to reduce CO2 emissions and adaptation measures designed to help marine ecosystems cope with changing conditions. International agreements such as the Paris Agreement seek to limit global warming by curbing greenhouse gas emissions. Research initiatives are underway to understand better how different species respond to varying acidity levels and temperature changes. This knowledge can guide conservation efforts and help develop strategies for restoring affected ecosystems.
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The implications of ocean acidification extend beyond ecological concerns to pose economic threats. Due to changing ocean chemistry, coastal communities that depend on fishing and tourism face potential fish stocks and coral reef health declines. As key species become less viable or disappear altogether, food security for millions could be compromised. Cultural practices and traditions tied to these environments may also be affected as marine ecosystems shift.
Recent studies call for immediate action before irreversible damage occurs within our oceans. The United Nations warns that without significant reductions in greenhouse gas emissions globally, we risk further accelerating this crisis with dire consequences for marine life and human communities worldwide.
Continue reading ‘Why ocean acidification is called climate change’s evil twin’The Southern Ocean Time Series: a climatological view of hydrography, biogeochemistry, phytoplankton community composition, and carbon export in the subantarctic zone
Published 25 December 2024 Science ClosedTags: Antarctic, chemistry, field
The Southern Ocean Time Series (SOTS) provides highly temporally resolved observations of the physical, chemical and biological variability in the upper ocean, as well as the export of particulate carbon to the ocean interior, in the subantarctic region south of Australia. The SOTS observatory focuses on the subantarctic region because of its importance in the formation of mode water and the associated uptake and storage of anthropogenic heat and carbon. The region is also critical for the supply of oxygen to the interior and the export of nutrients to fuel primary production in broad areas of the low latitude global ocean. The SOTS observatory is the longest running multidisciplinary initiative in the open Southern Ocean, and has delivered high quality observations from the surface to the seafloor for more than a decade, and for some parameters, over two decades, using two deep-water moorings. The moorings are serviced annually, providing additional opportunities for shipboard sampling and sensor validation and calibration. Using observations collected at the SOTS site between 1997 and 2022, the seasonal variability in upper ocean hydrography, biogeochemistry, phytoplankton community composition, and biodiversity, along with carbon export to the ocean interior are presented. This climatological view of the region is complemented by a review of recent findings underpinned by observations collected by the SOTS observatory and highlighting the ongoing need for long time series to better understand the subantarctic ocean and its response to a changing climate.
Continue reading ‘The Southern Ocean Time Series: a climatological view of hydrography, biogeochemistry, phytoplankton community composition, and carbon export in the subantarctic zone’A regional physical-biogeochemical ocean model for marine resource applications in the Northeast Pacific (MOM6-COBALT-NEP10k v1.0)
Published 25 December 2024 Science ClosedTags: Arctic, biogeochemistry, biological response, field, modeling, North Pacific, regionalmodeling, zooplankton
Regional ocean models enable generation of computationally-affordable and regionally-tailored \ ensembles of near-term forecasts and long-term projections of sufficient resolution to serve marine resource management. Climate change, however, has created marine resource challenges, such as shifting stock distributions, that cut across domestic and international management boundaries and have pushed regional modeling efforts toward “coastwide” approaches. Here we present and evaluate a multidecadal hindcast with a Northeast Pacific (NEP) regional implementation of the Modular Ocean Model version 6 with sea ice and biogeochemistry that extends from the Chukchi Sea to the Baja California Peninsula at 10-km horizontal resolution (MOM6-COBALT-NEP10k, or “NEP10k”). This domain includes an Arctic-adjacent system with a broad shallow shelf seasonally covered by sea ice (the Eastern Bering Sea, EBS), a sub-Arctic system with upwelling in the Alaska Gyre and predominant downwelling winds and large freshwater forcing along the coast (the Gulf of Alaska, GoA), and a temperate, eastern boundary upwelling ecosystem (the California Current Ecosystem, CCE). The coastwide model was able to recreate seasonal and cross-ecosystem contrasts in numerous ecosystem-critical properties including temperature, salinity, inorganic nutrients, oxygen, carbonate saturation states, and chlorophyll. Spatial consistency between modeled quantities and observations generally extended to plankton ecosystems, though small to moderate biases were also apparent. Fidelity with observed zooplankton biomass, for example, was limited to first-order seasonal and cross-system contrasts. Temporally, simulated monthly surface and bottom temperature anomalies in coastal regions (< 500m deep) closely matched estimates from data-assimilative ocean reanalyses. Performance, however, was reduced in some nearshore regions coarsely resolved by the model’s 10-km resolution grid, and the time series of satellite-based chlorophyll anomaly estimates proved more difficult to match than temperature. System-specific ecosystem indicators were also assessed. In the EBS, NEP10k robustly matched observed variations, including recent large declines, in the area of the summer bottom water “cold pool” (< 2 °C) which exerts a profound influence on EBS fisheries. In the GoA, the simulation captured patterns of sea surface height variability and variations in thermal, oxygen and acidification risk associated with local modes of inter-annual to decadal climate variability. In the CCE, the simulation robustly captured variations in upwelling indices and coastal water masses, though discrepancies in the latter were evident in the Southern California Bight. Enhanced model resolution may reduce such discrepancies, but any benefits must be carefully weighed against computational costs given the intended use of this system for ensemble predictions and projections. Meanwhile, the demonstrated NEP10k skill level herein, particularly in recreating cross-ecosystem contrasts and the time variation of ecosystem indicators over multiple decades, suggests considerable immediate utility for coastwide retrospective and predictive applications.
Continue reading ‘A regional physical-biogeochemical ocean model for marine resource applications in the Northeast Pacific (MOM6-COBALT-NEP10k v1.0)’Marine biological responses to abrupt climate change in deep time
Published 24 December 2024 Science ClosedTags: biological response, paleo, review
Non-technical Summary
Paleobiology can offer diverse insights into how climate change has affected past species and ecosystems. Timely and important areas of research focus on the potential of paleobiology to contribute to solutions for climate impacts on natural ecosystems. But how far can past responses to abrupt climate change be generalized to derive predictions for the modern and future worlds? The long timescales over which biological responses are observed in the deep time past hamper the applicability of paleontological observations, but by how much? To address these questions, we review paleontological evidence for the impacts of geologically rapid climatic change. Fruitful avenues for future research lie in (1) characterizing the relationship between the magnitude of warming and extinction toll, (2) using physiology to bridge timescales, and (3) assessing the role of long-term climate history to predict the impact of short-term climate change. Identifying how consistent and robust paleontological signals are across timescales will help to make deep-time observations more useful for the modern world.
Abstract
Ancient changes in the biosphere, from organismic traits to wholesale ecosystem changes, can be aligned with climate forcing across the Phanerozoic. Clear examples of abrupt climate warming causing biodiversity crises are primarily found between the Permian and Paleogene periods. During these times, catastrophic events occurred, resembling the extreme climate scenarios projected for the near future. The paleobiologic literature around these events generally supports the hypothesis that abrupt climate change was a dominant trigger of extinction and/or ecological crisis. When climate change and climate history are considered, virtually all post-Paleozoic global biotic events can be confidently attributed to climatic change, with abrupt warming (hyperthermal events) leaving the most consistent fingerprint. The combined stress of deoxygenation and warming are sufficient to explain marine extinction patterns across most hyperthermal events. Although ocean acidification may have contributed, the direct role of pH on the extinction toll of organisms is not consistently demonstrated. Future research can enhance the correspondence between the magnitudes of climatic changes and their biological impacts, even though observed rates of change cannot currently be compared across different timescales. Mimicking multi-scale approaches in modern ecology, paleontological approaches to climate impact research will benefit from specifically targeting scaling relationships
How does the interaction between the stress status of bivalves (Mytilus galloprovincialis) and marine environmental factors unfold through a principal component analysis approach?
Published 24 December 2024 Science ClosedTags: biological response, field, mollusks, North Atlantic, physiology
The Bay of Agadir, located in Morocco, is of significant economic and ecological value, yet it has faced persistent pollution challenges due to industrial, port, and tourism activities. Despite recent improvements following the implementation of wastewater treatment plants, particularly in the Anza-Imouran sector, knowledge gaps remain regarding the interactions between marine environmental factors and pollution biomarkers in marine organisms. This study examines the influence of environmental factors on the biomarker responses of Mytilus galloprovincialis across three sites (Anza, Aourir, and Imouran) in Agadir Bay, covering the period from January 2017 to December 2018. Principal Component Analysis (PCA) was employed to explore the relationships between four key biomarkers (Catalase (CAT), Glutathione S-transferase (GST), Malondialdehyde (MDA), and Acetylcholinesterase (AChE)), and seven marine environmental factors (water temperature, air temperature, salinity, pH, dissolved oxygen, electrical conductivity, and precipitation). At Anza, Aourir, and Imouran, the first two principal components explained a significant portion of the total variance (80.19%, 78.63%, and 88.60%, respectively). Notable findings include a negative correlation between GST and water temperature (r = − 0.57) at Anza. In Aourir, CAT exhibited a positive correlation with rainfall and dissolved oxygen (r = 0.78 and r = 0.41, respectively) but a negative correlation with pH and salinity (r = − 0.58 and r = − 0.44, respectively). Additionally, GST was positively correlated with rainfall (r = 0.52), while showing a negative relationship with pH and water temperature (r = − 0.40 and r = − 0.53, respectively). MDA was negatively correlated with salinity (r = − 0.59), and AChE was inversely associated with electrical conductivity (r = − 0.41). In Imouran, CAT was positively correlated with rainfall (r = 0.70), while exhibiting negative correlations with pH, salinity, and electrical conductivity (r = − 0.73, r = − 0.60, and r = − 0.61, respectively). GST showed a positive correlation with electrical conductivity and salinity (r = 0.55 and r = 0.48), but a negative correlation with water temperature (r = − 0.47). MDA was positively correlated with rainfall (r = 0.66) and negatively with pH, electrical conductivity, and salinity (r = − 0.74, r = − 0.58, and r = − 0.67, respectively). These findings highlight the intricate relationship between marine environmental factors and biomarker variability in M. galloprovincialis, emphasizing the importance of further understanding their impact on marine organism health amid ongoing environmental changes.
Continue reading ‘How does the interaction between the stress status of bivalves (Mytilus galloprovincialis) and marine environmental factors unfold through a principal component analysis approach?’Divergent responses of an armored and an unarmored dinoflagellate to ocean acidification
Published 24 December 2024 Science ClosedTags: biological response, growth, laboratory, molecular biology, physiology, phytoplankton
Highlights
- An armored and an unarmored dinoflagellate exhibited divergent responses to OA.
- The unarmored species presented a higher ability to withstand OA stress.
- Cell wall structure may play essential roles in response to OA stress.
- Unarmored dinoflagellates may have significant advantages in acidic oceans.
Abstract
Dinoflagellates, both armored and unarmored, with distinct cell wall difference, are being affected by elevated CO2-induced ocean acidification (OA). However, their specific responses to OA are not well understood. In this study, we investigated the physiological and molecular response of the armored species Prorocentrum obtusidens and the unarmored species Karenia mikimotoi to OA over a 28-day period. The results show that the two species responded differently to OA. Cell growth rate, particulate organic carbon (POC) content, and the activities of C4 pathway enzymes decreased in P. obtusidens under future acidified ocean condition (pH 7.8, 1000 μatm pCO2), but the activities of carbonic anhydrase (CA), ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), and superoxide dismutase (SOD) increased. Whereas cell growth rate, contents of Chl a and PON, and SOD activity altered insignificantly in K. mikimotoi, but contents of POC and total carbohydrate, and the activity of RubisCO increased while the activities of CA and C4 pathway enzymes decreased. Transcriptomic analysis indicates that genes associated with antioxidative response, heat shock protein, proteasome, signal transduction, ribosome, and pH regulation were up-regulated in P. obtusidens but down-regulated in K. mikimotoi. Notably, the synthesis of soluble organic matter (i.e., spermidine and trehalose) was enhanced in K. mikimotoi, thereby regulating intracellular pH and improving stress resistance. This study highlights the divergent response of the armored and unarmored dinoflagellates to OA, with the unarmored dinoflagellate exhibiting a higher ability to withstand this stressor. Therefore, caution should be exercised when predicting the behavior and the eventual fate of dinoflagellates in the future acidified ocean.
Continue reading ‘Divergent responses of an armored and an unarmored dinoflagellate to ocean acidification’
