The Impact of a Modest Anthropogenic Carbon Increase on the Carbonate Chemistry Balance of a Temperate Fjord System

2021 ◽  
Author(s):  
Tereza Jarnikova ◽  
Debby Ianson ◽  
Susan E. Allen ◽  
Andrew E. Shao ◽  
Elise M. Olson
Keyword(s):  
Coastal Region ◽  
Temporal Variations ◽  
Anthropogenic Change ◽  
Salish Sea ◽  
Carbonate Chemistry ◽  
Saturation State ◽  
Aragonite Saturation ◽  
The Pacific ◽  
Anthropogenic Carbon ◽  
The Impact

<p>Coastal regions are typically characterized by considerable physical variability that in turn leads to dramatic variability in coastal carbonate chemistry.  Recent shipboard and mooring-based observations have shown large spatial and temporal variations of carbonate chemistry parameters, including air-sea CO<sub>2</sub> flux and aragonite saturation state, in one prominent coastal region in the Northeast Pacific Ocean - the Salish Sea. The range of the observed variability in the regional carbonate system is significantly larger than the global anthropogenic change, complicating the detection of secular carbon trends. Simultaneously, sparse observations limit understanding of the carbonate balance as a whole. Here, we use a highly resolved coastal model, SalishSeaCast, to characterize the drivers of the carbonate chemistry balance of the Salish Sea, with an emphasis on air-sea CO<sub>2</sub> flux and aragonite saturation state. We then investigate the impact of a relatively modest increase in anthropogenic carbon in this region in the context of the governing physical and biological dynamics of the system. We examine the striking effects of the anthropogenic change to date on the inorganic carbon balance of the system, highlighting impacts on the aragonite saturation state of the system and its buffering capacity, as well as suggesting some bounds for the regional air-sea and lateral carbon fluxes. We then use the GLODAP dataset of global coastal carbon observations to consider our results in the context of other regions of the Pacific Rim and the global coastal ocean. </p>

scholarly journals Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

Ocean Science ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 937-951 ◽  
Author(s):  
Abdirahman M. Omar ◽  
Ingunn Skjelvan ◽  
Svein Rune Erga ◽  
Are Olsen
Keyword(s):  
Coastal Water ◽  
Spring Bloom ◽  
Dissolved Inorganic Carbon ◽  
Vertical Mixing ◽  
Late Summer ◽  
Early Spring ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Anthropogenic Carbon ◽  
Carbon Dioxide Co2

Abstract. The uptake of anthropogenic carbon dioxide (CO2) by the ocean leads to a process known as ocean acidification (OA), which lowers the aragonite saturation state (ΩAr) and pH, and this is poorly documented in coastal environments including fjords due to lack of appropriate observations.Here we use weekly underway data from the Voluntary Observing Ships (VOS) program covering the period 2005–2009 combined with data from research cruises to estimate ΩAr and pH values in several adjacent western Norwegian fjords, and to evaluate how seawater CO2 chemistry drives their variations in response to physical and biological factors.The OA parameters in the surface waters of the fjords are subject to strong seasonal and spatially coherent variations. These changes are governed by the seasonal changes in temperature, salinity, formation and decay of organic matter, and vertical mixing with deeper, carbon-rich coastal water. Annual mean pH and ΩAr values were 8.13 and 2.21, respectively. The former varies from minimum values ( ≈  8.05) in late December – early January to maximum values of around 8.2 during early spring (March–April) as a consequence of the phytoplankton spring bloom, which reduces dissolved inorganic carbon (DIC). In the following months, pH decreases in response to warming. This thermodynamic decrease in pH is reinforced by the deepening of the mixed layer, which enables carbon-rich coastal water to reach the surface, and this trend continues until the low winter values of pH are reached again. ΩAr, on the other hand, reaches its seasonal maximum (> 2.5) in mid- to late summer (July–September), when the spring bloom is over and pH is decreasing. The lowest ΩAr values ( ≈  1.3–1.6) occur during winter (January–March), when both pH and sea surface temperature (SST) are low and DIC is its highest. Consequently, seasonal ΩAr variations align with those of SST and salinity normalized DIC (nDIC).We demonstrate that underway measurements of fugacity of CO2 in seawater (fCO2) and SST from VOS lines combined with high frequency observations of the complete carbonate system at strategically placed fixed stations provide an approach to interpolate OA parameters over large areas in the fjords of western Norway.

scholarly journals Adaptation of Bivalve Molluscs to Environmental Conditions in the Coastal Region of El Jadida (Morocco): Case of Mytilus Galloprovincialis

2017 ◽  
Vol 13 (18) ◽  
pp. 226
Author(s):  
Essedaoui Aafaf ◽  
Messaoudi Abdelfettah ◽  
Ferssiwi Abdesslam ◽  
Massar Redouane ◽  
Bitar Abdelali
Keyword(s):  
Industrial Pollution ◽  
Mytilus Galloprovincialis ◽  
Coastal Region ◽  
Industrial Effluents ◽  
Condition Index ◽  
Temporal Variations ◽  
Reference Station ◽  
Significant Difference ◽  
El Jadida ◽  
The Impact

The aim of this study is to assess the impact of industrial pollution on the growth and reproduction of the mussel Mytilus galloprovincialis from coastal region of El Jadida (Morocco). To this aim, three stations (S1, S2 and S3) are chosen according to their proximity to the industrial effluents of the chemical complex. The seawater and mussels (N = 100/ station) samples have been randomly and monthly collected for a period of 6 months (February-July 16). Mussels are distributed in 6 classes of size and measures of condition index and gonadic index are performed in the most common size classes. The results of the analysis of physicochemical parameters of the water show spatio-temporal variations with an acidic pH, high temperature and low salinity in the station near of industrials effluents. Regarding condition index and the gonadic index, there is no significant difference between the mussels collected from the reference station (S2) and the polluted station (S3). This can be explained partly by the adoption of a strategy of adaptation to the environmental stress caused by the industrial pollution.

scholarly journals Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

2016 ◽  
Vol 67 (2) ◽  
pp. 163 ◽  
Author(s):  
Roberta C. Challener ◽  
Lisa L. Robbins ◽  
James B. McClintock
Keyword(s):  
Ocean Acidification ◽  
Daily Basis ◽  
Seagrass Beds ◽  
Seasonal Fluctuations ◽  
Carbonate Chemistry ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Coastal Species ◽  
Coastal Acidification ◽  
Ocean Observations

Open ocean observations have shown that increasing levels of anthropogenically derived atmospheric CO2 are causing acidification of the world’s oceans. Yet little is known about coastal acidification and studies are just beginning to characterise the carbonate chemistry of shallow, nearshore zones where many ecologically and economically important organisms occur. We characterised the carbonate chemistry of seawater within an area dominated by seagrass beds (Saint Joseph Bay, Florida) to determine the extent of variation in pH and pCO2 over monthly and daily timescales. Distinct diel and seasonal fluctuations were observed at daily and monthly timescales respectively, indicating the influence of photosynthetic and respiratory processes on the local carbonate chemistry. Over the course of a year, the range in monthly values of pH (7.36–8.28), aragonite saturation state (0.65–5.63), and calculated pCO2 (195–2537μatm) were significant. When sampled on a daily basis the range in pH (7.70–8.06), aragonite saturation state (1.86–3.85), and calculated pCO2 (379–1019μatm) also exhibited significant range and indicated variation between timescales. The results of this study have significant implications for the design of ocean acidification experiments where nearshore species are utilised and indicate that coastal species are experiencing far greater fluctuations in carbonate chemistry than previously thought.

scholarly journals Impact of Historical Climate Change on the Southern Ocean Carbon Cycle

2008 ◽  
Vol 21 (22) ◽  
pp. 5820-5834 ◽  
Author(s):  
R. J. Matear ◽  
A. Lenton
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Southern Ocean ◽  
Carbon Uptake ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Freshwater Fluxes ◽  
Anthropogenic Carbon ◽  
Natural Carbon ◽  
Ocean Carbon

Abstract Climate change over the last several decades is suggested to cause a decrease in the magnitude of the uptake of CO2 by the Southern Ocean (Le Quere et al.). In this study, the atmospheric fields from NCEP R1 for the years 1948–2003 are used to drive an ocean biogeochemical model to probe how changes in the heat and freshwater fluxes and in the winds affect the Southern Ocean’s uptake of carbon. Over this period, the model simulations herein show that the increases in heat and freshwater fluxes drive a net increase in Southern Ocean uptake (south of 40°S) while the increases in wind stresses drive a net decrease in uptake. The total Southern Ocean response is nearly identical with the simulation without climate change because the heat and freshwater flux response is approximately both equal and opposite to the wind stress response. It is also shown that any change in the Southern Ocean anthropogenic carbon uptake is always opposed by a much larger change in the natural carbon air–sea exchange. For the 1948–2003 period, the changes in the natural carbon cycle dominate the Southern Ocean carbon uptake response to climate change. However, it is shown with a simple box model that when atmospheric CO2 levels exceed the partial pressure of carbon dioxide (pCO2) of the upwelled Circumpolar Deep Water (≈450 μatm) the Southern Ocean uptake response will be dominated by the changes in anthropogenic carbon uptake. Therefore, the suggestion that the Southern Ocean carbon uptake is a positive feedback to global warming is only a transient response that will change to a negative feedback in the near future if the present climate trend continues. Associated with the increased outgassing of carbon from the natural carbon cycle was a reduction in the aragonite saturation state of the high-latitude Southern Ocean (south of 60°S). In the simulation with just wind stress changes, the reduction in the high-latitude Southern Ocean aragonite saturation state (≈0.2) was comparable to the magnitude of the decline in the aragonite saturation state over the last 4 decades because of rising atmospheric CO2 levels (≈0.2). The simulation showed that climate change could significantly impact aragonite saturation state in the Southern Ocean.

scholarly journals Historical reconstruction of ocean acidification in the Australian region

2015 ◽  
Vol 12 (11) ◽  
pp. 8265-8297 ◽  
Author(s):  
A. Lenton ◽  
B. Tilbrook ◽  
R. J. Matear ◽  
T. Sasse ◽  
Y. Nojiri
Keyword(s):  
Ocean Acidification ◽  
Dominant Mode ◽  
Ocean Dynamics ◽  
Atmospheric Co2 ◽  
Reference Station ◽  
Historical Reconstruction ◽  
Carbonate Chemistry ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Concentration Changes

Abstract. The increase in atmospheric greenhouse gases over the last 200 years has caused an increase in ocean acidity levels. Documenting how the ocean has changed is critical for assessing how these changes could impact marine ecosystems and for the management of marine resources. We use present day ocean carbon observations from shelf and offshore waters around Australia, combined with neural network mapping of CO2, to estimate the current seasonal and regional distributions of carbonate chemistry (pH and aragonite saturation state). These predicted changes in carbonate chemistry are combined with atmospheric CO2 concentration changes since to reconstruct pH and aragonite saturation state changes over the last 140 years (1870–2013). The comparison with data collected at Integrated Marine Observing System National Reference Station sites located on the shelf around Australia shows both the mean state and seasonality for the present day is well represented by our reconstruction, with the exception of sites such as the Great Barrier Reef. Our reconstruction predicts that since 1870 an average decrease in aragonite saturation state of 0.48 and of 0.09 in pH has occurred in response to increasing oceanic uptake of atmospheric CO2. Our reconstruction shows that seasonality is the dominant mode of variability, with only small interannual variability present. Large seasonal variability in pH and aragonite saturation state occur in Southwestern Australia driven by ocean dynamics (mixing) and in the Tasman Sea by seasonal warming (in the case of aragonite saturation state). The seasonal and historical changes in aragonite saturation state and pH have different spatial patterns and suggest that the biological responses to ocean acidification are likely to be non-uniform depending on the relative sensitivity of organisms to shifts in pH and saturation state. This new historical reconstruction provides an important to link to biological observations to help elucidate the consequences of ocean acidification.

scholarly journals The sensitivity of estuarine aragonite saturation state and pH to the carbonate chemistry of a freshet-dominated river

2017 ◽  
Author(s):  
Benjamin L. Moore-Maley ◽  
Debby Ianson ◽  
Susan E. Allen
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Coupled Model ◽  
Ph Sensitivity ◽  
Total Alkalinity ◽  
Low Flow ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Strait Of Georgia ◽  
River Chemistry ◽  
The Impact

Abstract. Ocean acidification threatens to reduce pH and aragonite saturation state (ΩA) in estuaries, potentially damaging their ecosystems. However, the impact of highly variable river total alkalinity (TA) and dissolved inorganic carbon (DIC) on pH and ΩA in these estuaries is unknown. We assess the sensitivity of estuarine surface pH and ΩA to river chemistry using a 1-dimensional, biogeochemical-coupled model of the Strait of Georgia on the Canadian Pacific coast and generalize the results in the context of global rivers. The productive Strait of Georgia estuary has a large, seasonally variable freshwater input from the glacially fed, undammed Fraser River. Analyzing TA and pH observations from this river and its estuary, we find that the Fraser is moderately alkaline (TA 500–1350 μmol kg−1) but relatively DIC-rich, especially during winter (low flow). Model results show that estuarine pH and ΩA, while sensitive to freshwater DIC and TA, do not vary in synchrony. Instead, rivers with high DIC and TA produce lower estuarine pH due to an increased estuarine DIC : TA ratio, but higher estuarine ΩA because of DIC contributions to the carbonate ion. This estuarine pH sensitivity decreases with increasing mean river TA, but the zone of maximum pH sensitivity also moves to higher salinity which could impact a larger areal extent of the estuary. Many temperate rivers, such as the Fraser, are expected to experience weaker freshets and stronger winter flows under climate change, reducing the extent of the river plume and the impact of river chemistry in much of the estuary. However, increasing carbon in rivers will move the highest sensitivity zone to higher salinities that cover larger areas under present-day flow regimes.

scholarly journals Coral records of reef-water pH across the central Great Barrier Reef, Australia: assessing the influence of river runoff on inshore reefs

2015 ◽  
Vol 12 (4) ◽  
pp. 1223-1236 ◽  
Author(s):  
J. P. D'Olivo ◽  
M. T. McCulloch ◽  
S. M. Eggins ◽  
J. Trotter
Keyword(s):  
Great Barrier Reef ◽  
River Runoff ◽  
River Discharge ◽  
Barrier Reef ◽  
Inner Shelf ◽  
Phytoplankton Productivity ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Water Ph ◽  
The Impact

Abstract. The boron isotopic (δ11Bcarb) compositions of long-lived Porites coral are used to reconstruct reef-water pH across the central Great Barrier Reef (GBR) and assess the impact of river runoff on inshore reefs. For the period from 1940 to 2009, corals from both inner- and mid-shelf sites exhibit the same overall decrease in δ11Bcarb of 0.086 ± 0.033‰ per decade, equivalent to a decline in seawater pH (pHsw) of ~0.017 ± 0.007 pH units per decade. This decline is consistent with the long-term effects of ocean acidification based on estimates of CO2 uptake by surface waters due to rising atmospheric levels. We also find that, compared to the mid-shelf corals, the δ11Bcarb compositions of inner-shelf corals subject to river discharge events have higher and more variable values, and hence higher inferred pHsw values. These higher δ11Bcarb values of inner-shelf corals are particularly evident during wet years, despite river waters having lower pH. The main effect of river discharge on reef-water carbonate chemistry thus appears to be from reduced aragonite saturation state and higher nutrients driving increased phytoplankton productivity, resulting in the drawdown of pCO2 and increase in pHsw. Increased primary production therefore has the potential to counter the more transient effects of low-pH river water (pHrw) discharged into near-shore environments. Importantly, however, inshore reefs also show a consistent pattern of sharply declining coral growth that coincides with periods of high river discharge. This occurs despite these reefs having higher pHsw, demonstrating the overriding importance of local reef-water quality and reduced aragonite saturation state on coral reef health.

The growing exposure of Pacific coral reefs to compound extremes caused by marine heatwaves coalescing with low saturation state extremes

2021 ◽  
Author(s):  
Luke Gregor ◽  
Nicolas Gruber
Keyword(s):  
Pacific Ocean ◽  
Coral Reefs ◽  
Extreme Events ◽  
Anthropogenic Heat ◽  
Average Intensity ◽  
Saturation State ◽  
The Pacific ◽  
Compound Events ◽  
The Pacific Ocean ◽  
The Impact

<p>The ocean has played a key role in mitigating the impact of climate change by taking up excess anthropogenic heat and CO<sub>2</sub> leading to warming and increased ocean acidity, which goes in hand with a reduction of the saturation state of seawater with regard to the mineral carbonate aragonite, <em>i.e.</em>, Ω<sub>AR</sub>. While the threats posed by these long-term changes to marine organisms and ecosystems are well recognized, only more recently has the community realized that these threats might be much more imminent owing to extreme events. This is the result of these extremes exposing vulnerable ecosystems already today to conditions that lie in the far future when considering only the changes in the mean conditions. Of particular concern are so-called compound events, <em>i.e.</em>, conditions when both temperatures are extremely hot and the saturation states extremely low, as this compounding might be particularly threatening for marine ecosystems, especially for warm water coral reefs.</p><p>Here we use satellite records of sea surface temperature (SST) and satellite Ω<sub>AR</sub> to map globally the occurrence of marine heat waves (MHW) and low saturation state extreme events and their compounding for the period 1985 and 2018. We use SSTs from the OSTIA product, while we take Ω<sub>AR</sub> from the newly developed OceanSODA-ETHZ (monthly 1°x1°) observation-based product that extrapolates ship observations with satellite data. Our study focuses on the Pacific Ocean between 25°S and 25°N, a region with more than 1000 identified coral reefs. We define extremes using the approach of Hobday et al. (2018) with a fixed baseline determined from the entire record (1985-2018) and where extremes are below/above the 10<sup>th</sup>/90<sup>th</sup> percentiles for Ω/SST respectively.</p><p>The majority of the compound extreme events (too hot and too low saturation state) occur in the western tropical Pacific, with 757 of the 1206 reefs in the Pacific experiencing at least three months of compound extreme events over the entire period. The average duration of these compound extremes was 3.6 months, and the average area was 247 600 km<sup>2</sup> (roughly the size of the United Kingdom). The compound events had an average intensity of –0.13 for Ω<sub>AR</sub> and 0.71°C, where the intensity is the anomaly from the climatology. The largest and longest lasting extreme event started in 2016 and lasted nearly three years, coinciding with the El Niño event over the same period, covering an area equivalent to Australia. These findings suggest that more than 60% of coral reefs in the Pacific Ocean are located in regions where heating events may have been compounded by decreased potential for calcification. Given the continuing increase in atmospheric CO<sub>2</sub>, the severity of this type of compound events is bound to increase in the future. </p>

scholarly journals The sensitivity of estuarine aragonite saturation state and pH to the carbonate chemistry of a freshet-dominated river

2018 ◽  
Vol 15 (12) ◽  
pp. 3743-3760 ◽  
Author(s):  
Benjamin L. Moore-Maley ◽  
Debby Ianson ◽  
Susan E. Allen
Keyword(s):  
Dissolved Inorganic Carbon ◽  
River Mouth ◽  
Total Alkalinity ◽  
Biogeochemical Model ◽  
Enhancement Effect ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Strait Of Georgia ◽  
Carbonate Ion ◽  
The Impact

Abstract. Ocean acidification threatens to reduce pH and aragonite saturation state (ΩA) in estuaries, potentially damaging their ecosystems. However, the impact of highly variable river total alkalinity (TA) and dissolved inorganic carbon (DIC) on pH and ΩA in these estuaries is unknown. We assess the sensitivity of estuarine surface pH and ΩA to river TA and DIC using a coupled biogeochemical model of the Strait of Georgia on the Canadian Pacific coast and place the results in the context of global rivers. The productive Strait of Georgia estuary has a large, seasonally variable freshwater input from the glacially fed, undammed Fraser River. Analyzing TA observations from this river plume and pH from the river mouth, we find that the Fraser is moderately alkaline (TA 500–1000 µmol kg−1) but relatively DIC-rich. Model results show that estuarine pH and ΩA are sensitive to freshwater DIC and TA, but do not vary in synchrony except at high DIC : TA. The asynchrony occurs because increased freshwater TA is associated with increased DIC, which contributes to an increased estuarine DIC : TA and reduces pH, while the resulting higher carbonate ion concentration causes an increase in estuarine ΩA. When freshwater DIC : TA increases (beyond  ∼  1.1), the shifting chemistry causes a paucity of the carbonate ion that overwhelms the simple dilution/enhancement effect. At this high DIC : TA ratio, estuarine sensitivity to river chemistry increases overall. Furthermore, this increased sensitivity extends to reduced flow regimes that are expected in future. Modulating these negative impacts is the seasonal productivity in the estuary which draws down DIC and reduces the sensitivity of estuarine pH to increasing DIC during the summer season.

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