Physiological adaptation of marine bivalves to global changes (M/F) in Argenton at IFREMER (in English)

Job title : Physiological adaptation of marine bivalves to global changes (M/F)

Reference:  PV-2020-096

Department/Office: Département des Ressources Biologiques et Environnement, Unité de recherche Physiologie Fonctionnelle des Organismes Marins, Laboratoire de Physiologie des Invertébrés

Duty station:  Landunvez, Bretagne, FR , France

Deadline for applications : 07/02/2021

Continue reading ‘Physiological adaptation of marine bivalves to global changes (M/F) in Argenton at IFREMER (in English)’

Seven countries in Gulf of Guinea to start monitoring ocean acidification

The BIOTTA (Building CapacIty in Ocean AcidificaTion MoniToring in the Gulf of GuineA) project will be the first coordinated effort in ocean acidification monitoring the Gulf of Guinea and other adjoining coasts in Africa.

With seed funding and equipment support from the Partnership for Observation of the Global Ocean (POGO) and The Ocean Foundation (TOF) respectively, BIOTTA will establish long-term Ocean Acidification monitoring stations in seven countries in West Africa (Liberia, Cote d’Ivoire, Ghana, Benin, Nigeria, Cameroon, and the Republic of Congo.

The leader of the BIOTTA working group Dr. Edem Mahu, from the Department of Marine and Fisheries Sciences of the University of Ghana, noted that “a lack of skillset and capacity in the measurement of ocean acidification in West Africa hinders our understanding of the phenomenon and threatens valuable economical and ecological resources in the Gulf of Guinea such as fisheries, aquaculture and tourism. This deficit in ocean acidification measurement skills forestalls our understanding of species vulnerability to changing pH and associated chemical reactions.  Ocean Acidification monitoring in this understudied area has come to stay and we will work assiduously to sustain this brilliant initiative.”

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Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters

Anthropogenic inputs into coastal ecosystems are causing more frequent environmental fluctuations and reducing seawater pH. One such ecosystem is Florida Bay, an important nursery for the Caribbean spiny lobster, Panulirus argus. Although adult crustaceans are often resilient to reduced seawater pH, earlier ontogenetic stages can be physiologically limited in their tolerance to ocean acidification on shorter time scales. We used a Y-maze chamber to test whether reduced-pH seawater altered the orientation of spiny lobster pueruli toward chemical cues produced by Laurencia spp. macroalgae, a known settlement cue for the species. We tested the hypothesis that pueruli conditioned in reduced-pH seawater would be less responsive to Laurencia spp. chemical cues than pueruli in ambient-pH seawater by comparing the proportion of individuals that moved to the cue side of the chamber with the proportion that moved to the side with no cue. We also recorded the amount of time (sec) before a response was observed. Pueruli conditioned in reduced-pH seawater were less responsive and failed to select the Laurencia cue. Our results suggest that episodic acidification of coastal waters might limit the ability of pueruli to locate settlement habitats, increasing postsettlement mortality.

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Rapid shifts in circulation and biogeochemistry of the Southern Ocean during deglacial carbon cycle events

The Southern Ocean plays a crucial role in regulating atmospheric CO2 on centennial to millennial time scales. However, observations of sufficient resolution to explore this have been lacking. Here, we report high-resolution, multiproxy records based on precisely dated deep-sea corals from the Southern Ocean. Paired deep (∆14C and δ11B) and surface (δ15N) proxy data point to enhanced upwelling coupled with reduced efficiency of the biological pump at 14.6 and 11.7 thousand years (ka) ago, which would have facilitated rapid carbon release to the atmosphere. Transient periods of unusually well-ventilated waters in the deep Southern Ocean occurred at 16.3 and 12.8 ka ago. Contemporaneous atmospheric carbon records indicate that these Southern Ocean ventilation events are also important in releasing respired carbon from the deep ocean to the atmosphere. Our results thus highlight two distinct modes of Southern Ocean circulation and biogeochemistry associated with centennial-scale atmospheric CO2 jumps during the last deglaciation.

Continue reading ‘Rapid shifts in circulation and biogeochemistry of the Southern Ocean during deglacial carbon cycle events’

Researchers publish rebuttal of prior study on ocean acidification effects on the behavior of coral reef fishes

Credit: CC0 Public Domain

A group of thirteen researchers from six countries has released a new scientific paper rejecting an earlier study claiming ocean acidification has no effects of the behavior of coral reef fishes.

Earlier this year, a paper by Clark et al. published in Nature claimed that previous experiments on the effects of elevated CO2 on reef fish behavior could not be repeated, and argued ocean acidification has no effects on the behaviors of coral reef fishes.

In a comprehensive rebuttal published in Nature, lead author Professor Philip Munday from the Centre of Excellence for Coral Reef Studies at James Cook University said there are fundamental methodological differences between the studies conducted in the “provocative” Clark et al. article and the earlier studies with which they made direct comparison.

Continue reading ‘Researchers publish rebuttal of prior study on ocean acidification effects on the behavior of coral reef fishes’

OceanSODA-ETHZ: A global gridded data set of the surface ocean carbonate system for seasonal to decadal studies of ocean acidification

Ocean acidification has altered the ocean’s carbonate chemistry profoundly since preindustrial times, with potentially serious consequences for marine life. Yet, no long-term global observation-based data set exists that permits to study changes in ocean acidification for all carbonate system parameters over the last few decades. Here, we fill this gap and present a methodologically consistent global data set of all relevant surface ocean parameters, i.e., dissolved inorganic carbon (DIC), total alkalinity (TA), partial pressure of CO2 (pCO2), pH, and the saturation state with respect to mineral CaCO3 (Ω) at monthly resolution over the period 1985 through 2018 at a spatial resolution of 1 × 1°. This data set, named OceanSODA-ETHZ, was created by extrapolating in time and space the surface ocean observations of pCO2 (from the Surface Ocean CO2 ATlas (SOCAT)) and total alkalinity (TA, from the Global Ocean Data Analysis Project (GLODAP)) using the newly developed Geospatial Random Cluster Ensemble Regression (GRaCER) method. This method is based on a two-step (cluster-regression) approach, but extends it by considering an ensemble of such cluster-regressions, leading to higher robustness. Surface ocean DIC, pH, and Ω were then computed from the globally mapped pCO2 and TA using the thermodynamic equations of the carbonate system. For the open ocean, the cluster regression method estimates pCO2 and TA with global near-zero biases and root mean squared errors of 12 µatm and 13 µmol kg−1, respectively. Taking into account also the measurement and representation errors, the total error increases to 14 µatm and 21 µmol kg−1, respectively. We assess the fidelity of the computed parameters by comparing them to direct observations from GLODAP, finding surface ocean pH and DIC global biases of near zero, and root mean squared errors of 0.023 and 16 µmol kg−1, respectively. These errors are very comparable to those expected by propagating the total errors from pCO2 and TA through the thermodynamic computations, indicating a robust and conservative assessment of the errors. We illustrate the potential of this new dataset by analyzing the climatological mean seasonal cycles of the different parameters of the surface ocean carbonate system, highlighting their commonalities and differences. The OceanSODA-ETHZ data can be downloaded from https://doi.org/10.25921/m5wx-ja34 (Gregor and Gruber, 2020).

Continue reading ‘OceanSODA-ETHZ: A global gridded data set of the surface ocean carbonate system for seasonal to decadal studies of ocean acidification’

Reply to: Methods matter in repeating ocean acidification studies

Replying to P. L. Munday et al. Nature https://doi.org/10.1038/s41586-020-2803-x (2020)

Pioneering papers by Munday and colleagues1,2 have reported profound effects of end-of-century ocean acidification—simulated by experimentally elevated CO2 levels in seawater—on the behaviour of coral reef fishes, such as extreme attraction of prey species to the chemical cues of their predators. Later studies by the same group reported that a range of other behaviours of coral reef fishes, including swimming activity, behavioural lateralization, homing and different predator avoidance behaviours, were also impaired by ocean acidification3 and that predator-escape behaviours in a coral reef mollusc were also impaired through the same physiological mechanism reported for fishes (that is, through effects on ‘GABAA-like receptors’), which led to the idea that “elevated-CO2 could cause behavioural impairment in a broad suite of marine animals”4. In 2014, we initiated experiments to further explore the physiological mechanism(s) that impaired coral reef fish behaviour in elevated levels of CO2; however, we immediately ran into a problem: despite several attempts, and many improvements to the standard methodology used in this field, we were unable to observe an effect of ocean acidification on fish behaviour. Our initial goal changed from what was meant to be a series of original experiments into a three-year effort to transparently examine behavioural effects of ocean acidification in coral reef fishes5; the findings of our study are the basis for the accompanying Comment by Munday et al.6.

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Methods matter in repeating ocean acidification studies

Arising from T. D. Clark et al. Nature https://doi.org/10.1038/s41586-019-1903-y (2020)

In their study, Clark et al.1 suggest that previous studies on the effects of elevated levels of CO2 on the behaviour of coral reef fishes are not repeatable and that ocean acidification does not impair the behaviour of coral reef fishes, even though six significant behavioural effects were detected in their study, each of which was dismissed for a different reason. They then compare the means and variances of six previous ocean acidification studies in fish with a data distribution that is derived from a multi-species compilation of their own data to conclude that the results of previous studies are statistically improbable. However, Clark et al.1 did not closely repeat previous studies, as they did not replicate key species, used different life stages and ecological histories and changed methods in important ways that reduce the likelihood of detecting the effects of ocean acidification.

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The effects of ocean acidification and warming on growth of a natural community of coastal phytoplankton

An in situ mesocosm experiment was performed to investigate the combined effects of ocean acidification and warming on the coastal phytoplankton standing stock and species composition of a eutrophic coastal area in the temperate-subtropical region. Experimental treatments of natural seawater included three CO2 and two temperature conditions (present control: ~400 μatm CO2 and ambient temperature, acidification conditions: ~900 μatm CO2 and ambient temperature, and greenhouse conditions: ~900 μatm CO2 and ambient temperature +3 °C). We found that increased CO2 concentration benefited the growth of small autotrophic phytoplankton groups: picophytoplankton (PP), autotrophic nanoflagellates (ANF), and small chain-forming diatoms (DT). However, in the greenhouse conditions, ANF and DT abundances were lower compared with those in the acidification conditions. The proliferation of small autotrophic phytoplankton in future oceanic conditions (acidification and greenhouse) also increased the abundance of heterotrophic dinoflagellates (HDF). These responses suggest that a combination of acidification and warming will not only increase the small autotrophic phytoplankton standing stock but, also, lead to a shift in the diatom and dinoflagellate species composition, with potential biogeochemical element cycling feedback and an increased frequency and intensity of harmful algal blooms.

Continue reading ‘The effects of ocean acidification and warming on growth of a natural community of coastal phytoplankton’

Declines in shellfish species on rocky seashores match climate-driven changes

Two decades of data from a study of Maine’s Swan’s Island document a slow and steady dwindling of mussels, barnacles, and snails

The waters of the Gulf of Maine are warming faster than oceans almost anywhere on Earth. And as the level of carbon dioxide rises in the atmosphere, it’s absorbed by the oceans, causing pH levels to fall. Ocean acidification makes it difficult for shellfish to thicken their shells — their primary defense against predators.

In a new study in the journal Communications Biology, researchers Peter Petraitis, a retired professor of biology in Penn’s School of Arts & Sciences, and Steve Dudgeon, a biology professor at California State University, Northridge, who completed a postdoctoral fellowship with Petraitis at Penn in the 1990s, show that the changing climate is taking a toll on Maine’s sea life. A dataset collected over two decades, including numbers of five species of mussels, barnacles, and snails, shows that all have been experiencing declines — some slow, some more rapid — in part owing to climate change.

“These species are often overlooked because of how common they are,” Petraitis says. “They’re just everywhere across the rocky shores. People don’t think anything is going to happen to them. If they decline by about 3% a year that’s a relatively small change so you might not notice it for a while. But one year, people are going to suddenly look around and say, ‘Where are all the snails, mussels and barnacles?'”

These species “form the core of an iconic food web” in the Gulf of Maine, says Dudgeon. “Concurrent declines of five species, including both native and non-native, is proportionally large, and may cause profound changes in the ecology of coastal oceans in the region.”

Continue reading ‘Declines in shellfish species on rocky seashores match climate-driven changes’

Declines over the last two decades of five intertidal invertebrate species in the western North Atlantic

Climate change has already altered the environmental conditions of the world’s oceans. Here we report declines in gastropod abundances and recruitment of mussels (Mytilus edulis) and barnacles (Semibalanus balanoides) over the last two decades that are correlated with changes in temperature and ocean conditions. Mussel recruitment is declining by 15.7% per year, barnacle recruitment by 5.0% per year, and abundances of three common gastropods are declining by an average of 3.1% per year (Testudinalia testudinalisLittorina littorea, and Nucella lapillus). The declines in mussels and the common periwinkle (L. littorea) are correlated with warming sea temperatures and the declines in T. testudinalis and N. lapillus are correlated with aragonite saturation state, which affects rates of shell calcification. These species are common on shores throughout the North Atlantic and their loss is likely to lead to simplification of an important food web on rocky shores.

Continue reading ‘Declines over the last two decades of five intertidal invertebrate species in the western North Atlantic’

Glacial drivers of marine biogeochemistry indicate a future shift to more corrosive conditions in an Arctic fjord

A detailed survey of a high Arctic glacier fjord (Kongsfjorden, Svalbard) was carried out in summer 2016, close to the peak of the meltwater season, in order to identify the effects of glacier runoff on nutrient distributions and the carbonate system. Short‐term weather patterns were found to exert a strong influence on freshwater content within the fjord. Freshwater inputs from glacier runoff and ice meltwater averaged (±SD) low nitrate (1.85±0.47 μM; 0.41±0.99 μM), orthophosphate (0.07±0.27 μM; 0.02 ±0.03 μM), dissolved organic carbon (27 ±14 μM in glacier runoff), total alkalinity (708±251 μmol kg‐1; 173±121 μmol kg‐1) and dissolved inorganic carbon (622±108 μmol kg‐1; 41±88 μmol kg‐1), as well as a modest silicate concentration (3.71±0.02 μM; 3.16±5.41 μM). pCO2 showed a non‐conservative behavior across the estuarine salinity gradient with a pronounced under‐saturation in the inner‐fjord, leading to strong CO2 uptake from the atmosphere. The combined effect of freshwater dilution and atmospheric CO2 absorption was the lowering of aragonite saturation state, to values that are known to negatively affect marine calcifiers (ΩAr, 1.07). Glacier discharge was therefore a strong local amplifier of ocean acidification. Future increases in discharge volume and the loss of marine productivity following the retreat of marine‐terminating glaciers inland are both anticipated to further lower ΩAr within inner‐fjord surface waters. This shift may be partially buffered by an increase in the mean freshwater total alkalinity as the fractional importance of iceberg melt to freshwater fjord inputs declines and runoff increases.

Continue reading ‘Glacial drivers of marine biogeochemistry indicate a future shift to more corrosive conditions in an Arctic fjord’

Short-term effects of increased CO2, nitrate and temperature on photosynthetic activity in Ulva rigida (Chlorophyta) estimated by different pulse amplitude modulated fluorometers and oxygen evolution

Short-term effects of pCO2 (700 – 380 ppm; HC-LC) and nitrate content (50-5 βM; HN-LC) on photosynthesis, estimated by different pulse amplitude modulated (PAMs) fluorometers and by oxygen evolution, were investigated in Ulva rigida (Chlorophyta) under solar radiation (ex-situ) and in the laboratory under artificial light (in-situ). After 6-days of incubation at ambient temperature (AT), algae were subjected to a 4 oC-temperature increase (AT+4oC) for 3 d. Both in-situ and ex-situ, maximal electron transport rate (ETRmax) and in situ gross photosynthesis (GP) measured by O2 evolution presented the highest values under HCHN, and the lowest under HCLN, across all measuring systems. Maximal quantum yield (Fv/Fm), and ETRmax of PSII (ETR(II)max) and of PSI (ETR(I)max), decreased under HCLN under AT+4°C. Ex situ ETR was higher than in situ ETR. At noon, Fv/Fm decreased (indicating photoinhibition), whereas ETR(II)max and maximal non-photochemical quenching (NPQmax) increased. ETR(II)max decreased under AT+4oC in contrast to Fv/Fm, photosynthetic efficiency (αETR) and saturated irradiance (EK). Thus, U. rigida exhibited a decrease in photosynthetic production under acidification, LN levels and AT+4oC. These results emphasize the importance of studying the interactive effects between environmental parameters using in-situ vs. ex-situ conditions when aiming to evaluate the impact of global change on marine macroalgae.

Continue reading ‘Short-term effects of increased CO2, nitrate and temperature on photosynthetic activity in Ulva rigida (Chlorophyta) estimated by different pulse amplitude modulated fluorometers and oxygen evolution’

Evolution of deep-sea sediments across the Paleocene-Eocene and Eocene-Oligocene boundaries

The composition and distribution of deep-sea sediments is the result of a multitude of climatic, biotic and oceanic conditions relating to biogeochemical cycles and environmental change. Here we utilize the extensive sediment archives of the International Ocean Discovery Program (IODP) and its predecessors to construct maps of deep-sea sediment type across two critical but contrasting boundaries in the Paleogene, one characterised by an interval of extreme warmth (Paleocene/Eocene) and the other by global cooling (Eocene/Oligocene). Ocean sediment distribution shows significant divergence both between the latest Paleocene and Paleocene Eocene Thermal Maximum (PETM), across the Eocene-Oligocene Transition (EOT), and in comparison to modern sediment distributions. Carbonate sedimentation in the latest Paleocene extends to high southern latitudes. Disappearance of carbonate sediments at the PETM is well documented and can be attributed to dissolution caused by significant ocean acidification as a result of carbon-cycle perturbation. Biosiliceous sediments are rare and it is posited that the reduced biogenic silica deposition at the equator is commensurate with an overall lack of equatorial upwelling in the early Paleogene ocean. In the Southern Ocean, we attribute the low in biosiliceous burial, to the warm deep water temperatures which would have impacted biogenic silica preservation. In the late Eocene, our sediment depositional maps record a tongue of radiolarian ooze in the eastern equatorial Pacific. Enhanced biosiliceous deposits in the late Eocene equatorial Pacific and Southern Ocean are due to increased productivity and the spin-up of the oceans. Our compilation documents the enhanced global carbonate sedimentation in the early Oligocene, confirming that the drop in the carbonate compensation depth was global.

Continue reading ‘Evolution of deep-sea sediments across the Paleocene-Eocene and Eocene-Oligocene boundaries’

Diel vertical migration into anoxic and high-pCO2 waters: acoustic and net-based krill observations in the Humboldt Current

A select group of marine organisms can enter the Oxygen Minimum Zones (OMZs) and even anoxic waters, while performing diel vertical migration (DVM). DVM of the euphausiid Euphausia eximia off northern Chile in the spring of 2015 was documented based on acoustic measurements using an echo sounder along with net samplings. Dissolved oxygen (DO) concentrations were obtained using a vertical profiler, and water samples were collected to obtain in situ nitrite (NO2) concentrations as well as pHT, total alkalinity (AT), and therefore carbon dioxide partial pressure (pCO2) was estimated. Krill were found to migrate up to the surface (0–50 m) during the night and returned to ca. 200–300 m depth during the day, spending between 11 and 14 h at these layers. At the surface, DO and NO2 concentrations were 208 and 0.14 μM respectively, while pHT was 8.04 and 405 μatm pCO2. In contrast, at the deeper layers (200–300 m), DO and NO2 were < 3 and 6.3 μM respectively, with pHT 7.53 and 1490 μatm pCO2. The pHT and high pCO2 values at depths represent the conditions predicted for open ocean waters in a worst-case global warming scenario by 2150. The acoustic scatter suggested that > 60% of the krill swarms enter the OMZ and anoxic waters during the daytime. These frequent migrations suggest that krill can tolerate such extreme conditions associated with anoxic and high-pCO2 waters. The inferences drawn from the observation of these migrations might have strong implications for the current oceanic carbon pump models, highlighting the need for understanding the molecular and physiological adaptations allowing these migrations.

Continue reading ‘Diel vertical migration into anoxic and high-pCO2 waters: acoustic and net-based krill observations in the Humboldt Current’

Ocean acidification impacts on zooplankton

Rising atmospheric CO2 alters the ocean biochemistry in the process known as ocean acidification (OA). It influences biodiversity at different levels, including zooplankton, which is a key component of aquatic communities and plays a pivotal role in the structure and functioning of marine planktonic food webs as a major link between pelagic primary producers and planktivorous. The effect of OA on the fitness of individual zooplanktonic species has been reported by many studies mostly developed under laboratory conditions. In this context, this chapter reviews the OA effects on zooplankton and describes the potential of natural shallow-water CO2 vents as in situ laboratories. The impact on zooplankton assemblages is shown from a study in the North Atlantic (Azores islands) and the suitability of this area for future studies on marine organisms and ecosystems. Sites with naturally elevated CO2 conditions are described, including which variables and limitations must be considered. Results shown are highly relevant to improve our predictions of the responses of zooplankton to climate change stressors including OA. Future studies including long-term multigenerational exposure to multiple stressors (e.g. increased pCO2 and food shortage) are a priority to understand the adaptation capacity of common species and how the zooplankton communities will shift.

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La Parguera (video; in Spanish)

Since 2008 the NOAA’s Ocean Acidification program (OAP) buoy has been installed in La Parguera, Puerto Rico where oceanographic studies of chemistry, biology, geology, and physics of the Caribbean Sea have been conducted for more than 50 years. Below is a video on La Parguera and Ocean Acidification.

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Early development and metabolic rate of the sea louse Caligus rogercresseyi under different scenarios of temperature and pCO2

Highlights

  • The temperature has a significant effect on the hatching time of C. royercresseyi.

  • Combination of pCO2 and temperature has a significant effect on survival in C. rogercresseyi.

  • The combination of pCO2 and temperature had no impact on the size of nauplius I, nauplius II and copepodid stage.

  • Only the temperature has a significant effect on oxygen consumption rate of C. royercresseyi.

Abstract

Anthropogenic CO2 emissions have led to ocean acidification and a rise in the temperature. The present study evaluates the effects of temperature (10, 15 and 20 °C) and pCO2 (400 and 1200 μatm) on the early development and oxygen consumption rate (OCR) of the sea louse Caligus rogercresseyi. Only temperature has an effect on the hatching and development times of nauplius I. But both factors affected the development time of nauplius II (<temperature = longer development time). Copepodid survival time was also affected by temperature and pCO2, at 10 °C and 400 μatm, survival was 30 and 44% longer than at 15 and 20 °C. OCRs were impacted by temperature but not by pCO2. In all treatments, OCR was lower for nauplius II than for the copepodid. Our results show the need to further evaluate the effects of a combination of environmental drivers on the performance of C. rogercresseyi, in a changing and uncertain future.

Continue reading ‘Early development and metabolic rate of the sea louse Caligus rogercresseyi under different scenarios of temperature and pCO2’

Fact sheet: Ocean acidification: pH variability across space and time

The absorption of atmospheric carbon dioxide by the oceans has changed the chemical properties of seawater and made it more acidic all over the world. Florida, with an extensive coastline and deep cultural and economic ties to marine resources, will be directly affected. This 4-page fact sheet written by Lisa Krimsky, Joseph Henry, and Joshua Patterson and published by the UF/IFAS Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation focuses on the spatial and temporal variability in oceanic pH and provide an overview of pH variability in Florida’s coastal waters.

https://edis.ifas.ufl.edu/fa227

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Benthic respiration in hypoxic waters enhances bottom water acidification in the northern Gulf of Mexico

It is known that surface water eutrophication enhances bottom water ocean acidification via respiration in coastal oceans. However, the role of benthic processes in influencing bottom water acidification has not been sufficiently explored. We examined this issue by analyzing a 10‐year summer carbonate chemistry dataset in bottom water together with recent benthic flux measurements and literature benthic flux data in the northern Gulf of Mexico. The difference between the observed and estimated pH (Ω) values calculated from anthropogenic CO2 increase and water column aerobic respiration were defined as ΔpH (ΔΩ). We found that ΔpH and ΔΩ values in hypoxic condition were −0.03 ± 0.04 (mean ± standard deviation) and −0.15 ± 0.39, respectively. Both ΔpH and ΔΩ values in hypoxic conditions were significantly lower than zero (p < 0.05). The net results of anaerobic respiration, oxidation of reduced chemcials, burial of iron sulfide minerals, and possible CaCO3 dissolution may have led to an alkalinity to DIC production ratio of less than 1 in porewater. This caused the ratio of alkalinity to dissolved inorganic carbon fluxes from sediment to bottom water to be less than 1, which led to additional bottom water acidification. Our analysis and model simulations demonstrate that severe hypoxic and anoxic conditions, which correspond to less water movement, favor the accumulation of benthic respiration products, leading to additional pH and Ω reductions. The findings on sediment processes contributing to acidification in bottom waters provide new insights into the sensitivity of coastal ocean acidification to low‐oxygen conditions under current and future climates and anthropogenic nutrient loading scenarios.

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