We report results from an oyster hatchery on the Oregon coast, where intake waters experienced variable carbonate chemistry (aragonite saturation state < 0.8 to > 3.2; pH < 7.6 to > 8.2) in the early ...summer of 2009. Both larval production and midstage growth (∼ 120 to ∼ 150 μm) of the oyster Crassostrea gigas were significantly negatively correlated with the aragonite saturation state of waters in which larval oysters were spawned and reared for the first 48 h of life. The effects of the initial spawning conditions did not have a significant effect on early-stage growth (growth from D-hinge stage to ∼ 120 μm), suggesting a delayed effect of water chemistry on larval development.
The ocean's chemistry is changing due to the uptake of anthropogenic carbon dioxide (CO
). This phenomenon, commonly referred to as "Ocean Acidification", is endangering coral reefs and the broader ...marine ecosystems. In this study, we combine a recent observational seawater CO
data product, i.e., the 6
version of the Surface Ocean CO
Atlas (1991-2018, ~23 million observations), with temporal trends at individual locations of the global ocean from a robust Earth System Model to provide a high-resolution regionally varying view of global surface ocean pH and the Revelle Factor. The climatology extends from the pre-Industrial era (1750 C.E.) to the end of this century under historical atmospheric CO
concentrations (pre-2005) and the Representative Concentrations Pathways (post-2005) of the Intergovernmental Panel on Climate Change (IPCC)'s 5
Assessment Report. By linking the modeled pH trends to the observed modern pH distribution, the climatology benefits from recent improvements in both model design and observational data coverage, and is likely to provide improved regional OA trajectories than the model output could alone, therefore, will help guide the regional OA adaptation strategies. We show that air-sea CO
disequilibrium is the dominant mode of spatial variability for surface pH, and discuss why pH and calcium carbonate mineral saturation states, two important metrics for OA, show contrasting spatial variability.
Thecosome pteropods are abundant upper-ocean zooplankton that build aragonite shells. Ocean acidification results in the lowering of aragonite saturation levels in the surface layers, and several ...incubation studies have shown that rates of calcification in these organisms decrease as a result. This study provides a weight-specific net calcification rate function for thecosome pteropods that includes both rates of dissolution and calcification over a range of plausible future aragonite saturation states (Ω(ar)). We measured gross dissolution in the pteropod Limacina helicina antarctica in the Scotia Sea (Southern Ocean) by incubating living specimens across a range of aragonite saturation states for a maximum of 14 days. Specimens started dissolving almost immediately upon exposure to undersaturated conditions (Ω(ar) ∼ 0.8), losing 1.4% of shell mass per day. The observed rate of gross dissolution was different from that predicted by rate law kinetics of aragonite dissolution, in being higher at Ω(ar) levels slightly above 1 and lower at Ω(ar) levels of between 1 and 0.8. This indicates that shell mass is affected by even transitional levels of saturation, but there is, nevertheless, some partial means of protection for shells when in undersaturated conditions. A function for gross dissolution against Ω(ar) derived from the present observations was compared to a function for gross calcification derived by a different study, and showed that dissolution became the dominating process even at Ω(ar) levels close to 1, with net shell growth ceasing at an Ω(ar) of 1.03. Gross dissolution increasingly dominated net change in shell mass as saturation levels decreased below 1. As well as influencing their viability, such dissolution of pteropod shells in the surface layers will result in slower sinking velocities and decreased carbon and carbonate fluxes to the deep ocean.
Ocean Acidification FEELY, RICHARD A.; DONEY, SCOTT C.; COOLEY, SARAH R.
Oceanography (Washington, D.C.),
12/2009, Letnik:
22, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The uptake of anthropogenic CO₂ by the global ocean induces fundamental changes in seawater chemistry that could have dramatic impacts on biological ecosystems in the upper ocean. Estimates based on ...the Intergovernmental Panel on Climate Change (IPCC) business-as-usual emission scenarios suggest that atmospheric CO₂ levels could approach 800 ppm near the end of the century. Corresponding biogeochemical models for the ocean indicate that surface water pH will drop from a pre-industrial value of about 8.2 to about 7.8 in the IPCC A2 scenario by the end of this century, increasing the ocean's acidity by about 150% relative to the beginning of the industrial era. In contemporary ocean water, elevated CO₂ will also cause substantial reductions in surface water carbonate ion concentrations, in terms of either absolute changes or fractional changes relative to pre-industrial levels. For most open-ocean surface waters, aragonite undersaturation occurs when carbonate ion concentrations drop below approximately 66 μmol kg⁻¹. The model projections indicate that aragonite undersaturation will start to occur by about 2020 in the Arctic Ocean and 2050 in the Southern Ocean. By 2050, all of the Arctic will be undersaturated with respect to aragonite, and by 2095, all of the Southern Ocean and parts of the North Pacific will be undersaturated. For calcite, undersaturation occurs when carbonate ion concentration drops below 42 μmol kg⁻¹. By 2095, most of the Arctic and some parts of the Bering and Chukchi seas will be undersaturated with respect to calcite. However, in most of the other ocean basins, the surface waters will still be saturated with respect to calcite, but at a level greatly reduced from the present.
The absorption of atmospheric carbon dioxide (CO₂) into the ocean lowers the pH of the waters. This so-called ocean acidification could have important consequences for marine ecosystems. To better ...understand the extent of this ocean acidification in coastal waters, we conducted hydrographic surveys along the continental shelf of western North America from central Canada to northern Mexico. We observed seawater that is undersaturated with respect to aragonite upwelling onto large portions of the continental shelf, reaching depths of ∼40 to 120 meters along most transect lines and all the way to the surface on one transect off northern California. Although seasonal upwelling of the undersaturated waters onto the shelf is a natural phenomenon in this region, the ocean uptake of anthropogenic CO₂ has increased the areal extent of the affected area
We report seawater boron concentration (mg
kg
−1) and chlorinity (‰) values measured in seawater samples (
n
=
139) collected at various depths in the North Pacific and North Atlantic oceans and the ...East/Japan Sea (located in the western temperate North Pacific). Our results indicate that variations in seawater boron concentration are strongly coupled to variations in chlorinity (and salinity), yielding a mean boron to chlorinity ratio of 0.2414
±
0.0009
mg
kg
−1
‰
−1 (boron to salinity ratio
=
0.1336
±
0.0005
mg
kg
−1
‰
−1). This ratio was surprisingly universal throughout the water column in the three marine basins and across widely different ocean surface regimes, but differs from the generally accepted ratio of 0.232
±
0.005
mg
kg
−1
‰
−1 determined by
Uppström (1974), which was based on only 20 measurements at four sites in the tropical Pacific Ocean. In converting total alkalinity to carbonate alkalinity (and vice versa) for thermodynamic calculations, the difference between these two ratios leads to a difference of 5
μmol
kg
−1 in estimates for ocean surface waters, where the contribution of borate to total alkalinity is typically greatest. We suggest the use of the new boron to chlorinity ratio for predicting seawater boron concentrations using chlorinity (or salinity) data.
Fabry, V. J., Seibel, B. A., Feely, R. A., and Orr, J. C. 2008. Impacts of ocean acidification on marine fauna and ecosystem processes. – ICES Journal of Marine Science, 65: 414–432. Oceanic uptake ...of anthropogenic carbon dioxide (CO2) is altering the seawater chemistry of the world’s oceans with consequences for marine biota. Elevated partial pressure of CO2 (pCO2) is causing the calcium carbonate saturation horizon to shoal in many regions, particularly in high latitudes and regions that intersect with pronounced hypoxic zones. The ability of marine animals, most importantly pteropod molluscs, foraminifera, and some benthic invertebrates, to produce calcareous skeletal structures is directly affected by seawater CO2 chemistry. CO2 influences the physiology of marine organisms as well through acid-base imbalance and reduced oxygen transport capacity. The few studies at relevant pCO2 levels impede our ability to predict future impacts on foodweb dynamics and other ecosystem processes. Here we present new observations, review available data, and identify priorities for future research, based on regions, ecosystems, taxa, and physiological processes believed to be most vulnerable to ocean acidification. We conclude that ocean acidification and the synergistic impacts of other anthropogenic stressors provide great potential for widespread changes to marine ecosystems.
The accumulation of anthropogenic CO₂ in the ocean has major ecological, socioeconomic, and biogeochemical impacts, with repercussions for the ocean as a critical carbon sink. Ocean acidification ...(OA) disproportionately affects marine calcifiers, among which pelagic zooplanktonic pteropods play a significant role in carbonate export. The pteropod, due to the susceptibility of its aragonite shell to rapid dissolution, is one of most vulnerable groups and a key indicator for OA regional monitoring, but its regional sensitivities have not yet been extrapolated over global scales. To delineate spatial and temporal changes in pteropod shell dissolution, global OA status and the OA rate of change were evaluated, based on gridded climatologies of observations and using a Regional Ocean Modeling System (ROMS) biogeochemical/ecosystem model. Pteropods, which dominate in the polar and subpolar regions, are characterized by low aragonite saturation state and low buffering capacity, where extended pteropod subsurface dissolution is projected. We show that pteropods are most susceptible to OA in the polar regions, subpolar North Pacific, and eastern boundary upwelling system regions, particularly the California and Humboldt Current Systems. Rates of acidification and corresponding increases in pteropod shell dissolution are projected to be the fastest in the North and South Equatorial Currents. These are the regions with the greatest impacts on pteropods and biogeochemical implications.
In 2007, the US west coast shellfish industry began to feel the effects of unprecedented levels of larval mortality in commercial hatcheries producing the Pacific oysterCrassostrea gigas. ...Subsequently, researchers at Whiskey Creek Shellfish Hatchery, working with academic and government scientists, showed a high correlation between aragonite saturation state (Ωarag) of inflowing seawater and survival of larval groups, clearly linking increased CO₂ to hatchery failures. This work led the Pacific Coast Shellfish Growers Association (PCSGA) to instrument shellfish hatcheries and coastal waters, establishing a monitoring network in collaboration with university researchers and the US Integrated Ocean Observing System. Analytical developments, such as the ability to monitor Ωaragin real time, have greatly improved the industry's understanding of carbonate chemistry and its variability and informed the development of commercial-scale water treatment systems. These treatment systems have generally proven effective, resulting in billions of additional oyster larvae supplied to Pacific Northwest oyster growers. However, significant challenges remain, and a multifaceted approach, including selective breeding of oyster stocks, expansion of hatchery capacity, continued monitoring of coastal water chemistry, and improved understanding of biological responses will all be essential to the survival of the US west coast shellfish industry.
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