Acidification of seawater owing to oceanic uptake of atmospheric CO2 originating from human activities such as burning of fossil fuels and land-use changes has raised serious concerns regarding its adverse effects on corals and calcifying communities. Here we demonstrate a net loss of calcium carbonate (CaCO3) material as a result of decreased calcification and increased carbonate dissolution from replicated subtropical coral reef communities (n=3) incubated in continuous-flow mesocosms subject to future seawater conditions.
Bar-built estuaries are coastal environments characterized by the partial closure of the estuary's mouth with a sandbar barrier for extended periods (closed state). Through natural events (rainfall) or anthropogenic influences, the sandbar is breached, reopening the estuary to the ocean. The transition from closed to open state often leads to extensive physical and chemical changes in the estuarine conditions, as water mixing and sediment resuspension are increased, which could result in the oxidation of sediment acid-volatile sulfides (AVS).
We tested the sensitivity of the vertical distributions and shell dissolution patterns of thecosome pteropods to spatial gradients associated with an eddy-associated front in the southern California Current System. The aragonite saturation horizon ($Ømega$arag = 1.0) shoaled from \textgreater200 to \textless75 m depth across the front. The vertical distribution of thecosome pteropods tracked these changes, with all 5 species showing reduced occurrence at depths below 100 m where waters were less saturated with respect to aragonite.
Based on six cruises from March to September in 2016, we investigated monthly distributions of dissolved organic matter (DOM) and ancillary water chemistry parameters in a mariculture area in the Northern Yellow Sea, where summertime hypoxia and seawater acidification were observed. The most severe oxygen depletion (hypoxia covered approximately one-third of the aquaculture area) and the largest pH decrease (8.07 ± 0.05 in surface layer vs. 7.66 ± 0.07 in bottom layer) were revealed in August.
An expedition abroad the R/V Professor Gagaranskii was conducted in the water area of the north-western shelf of the Sea of Okhotsk and the Tatar Strait to study the production and destruction of organic matter, as well as the biochemical processes governing the distribution and accumulation of particulate and dissolves forms of microelements (Fe, Mn, Zn, Cu, Cs, Ni, Pb) in a coastal and estuary ecosystems.
Based on a survey conducted from June to July 2013, aragonite saturation state variation and control in the river-dominated marginal BoHai and Yellow seas were investigated. Surface water $Ømega$arag ranged from 2.0–3.8, whereas subsurface water $Ømega$arag was generally lower than 2.0. Temperature changes had a strong influence on $Ømega$arag through induced CO2 solubility changes in seawater. Riverine freshwater input decreased $Ømega$arag in the Changjiang and Yalu river estuaries, but induced higher $Ømega$arag in the Yellow River estuary.
The North Yellow Sea (NYS) is a western North Pacific marginal sea of major ecological and economic importance, where seasonal thermocline and subsurface cold water mass are well developed from spring to autumn. Earlier researchers have shown monthly/bimonthly declines of pH ($Δ$pH) and aragonite saturation state ($Δ$$Ømega$arag) in the NYS cold water mass.
Reconstructing aragonite saturation state based on an empirical relationship for Northern California
Ocean acidification is a global phenomenon with highly regional spatial and temporal patterns. In order to address the challenges of future ocean acidification at a regional scale, it is necessary to increase the resolution of spatial and temporal monitoring of the inorganic carbon system beyond what is currently available. One approach is to develop empirical regional models that enable aragonite saturation state to be estimated from existing hydrographic measurements, for which greater spatial coverage and longer time series exist in addition to higher spatial and temporal resolution.
Oceans worldwide are undergoing acidification due to the penetration of anthropogenic CO2 from the atmosphere1,2,3,4. The rate of acidification generally diminishes with increasing depth. Yet, slowing down of the thermohaline circulation due to global warming could reduce the pH in the deep oceans, as more organic material would decompose with a longer residence time. To elucidate this process, a time-series study at a climatically sensitive region with sufficient duration and resolution is needed.
Long-term seawater pH records are essential for evaluating the rates of ocean acidification (OA) driven by anthropogenic emissions. Widespread, natural decadal variability in seawater pH superimposes on the long-term anthropogenic variations, likely influencing the OA rates estimated from the pH records. Here, we report a record of annual seawater pH estimated using the $δ$11B proxy over the past 159 years reconstructed from a Porites coral collected to the east of Hainan Island in the northern South China Sea (SCS).
The influence of ocean acidification in deep-sea ecosystems is poorly understood, but is expected to be large owing to the presumed low tolerance of deep-sea taxa to environmental change. We used a newly developed deep-sea Free Ocean CO2 Enrichment (dp-FOCE) system1 to evaluate the potential consequences of future ocean acidification on the feeding behavior of a deep-sea echinoid, the sea urchin, Strongylocentrotus fragilis. The dp-FOCE system simulated future ocean acidification inside an experimental enclosure where observations of feeding behavior were performed.
Increasing CO2 in seawater (i.e. ocean acidification) may have various and potentially adverse effects on phytoplankton dynamics and hence the organic carbon dynamics. We conducted a CO2 manipulation experiment in the Sea of Okhotsk in summer 2006 to investigate the response of the organic carbon dynamics.
Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA).
Puget Sound is a large estuary complex in the U.S. Pacific Northwest that is home to a diverse and economically important ecosystem threatened by anthropogenic impacts associated with climate change, urbanization, and ocean acidification. While ocean acidification has been studied in oceanic waters, little is known regarding its status in estuaries. Anthropogenically acidified coastal waters upwelling along the western North American continental margin can enter Puget Sound through the Strait of Juan de Fuca.
By the end of this century, anthropogenic carbon dioxide (CO2) emissions are expected to decrease the surface ocean pH by as much as 0.3 unit. At the same time, the ocean is expected to warm with an associated expansion of the oxygen minimum layer (OML). Thus, there is a growing demand to understand the response of the marine biota to these global changes. We show that ocean acidification will substantially depress metabolic rates (31%) and activity levels (45%) in the jumbo squid, Dosidicus gigas, a top predator in the Eastern Pacific. This effect is exacerbated by high temperature.
A new, in-situ sensing system, Channelized Optical System (CHANOS), was recently developed to make high-resolution, simultaneous measurements of total dissolved inorganic carbon (DIC) and pH in seawater. Measurements made by this single, compact sensor can fully characterize the marine carbonate system. The system has a modular design to accommodate two independent, but similar measurement channels for DIC and pH. Both are based on spectrophotometric detection of hydrogen ion concentrations.
The California Undercurrent transports Pacific Equatorial Water (PEW) into the Southern California Bight from the eastern tropical Pacific Ocean. PEW is characterized by higher temperatures and salinities, with lower pH, representing a source of potentially corrosive (aragonite, inline image) water to the region. We use ichthyoplankton assemblages near the cores of the California Current and the California Undercurrent to determine whether PEW influenced fish diversity.
Recent observations of calcium carbonate (CaCO3) mineral undersaturations on the Bering Sea Shelf have prompted new interest in the physical and biological factors that control the inorganic carbon system in the region. Understanding of the dynamics that influence the spatio-temporal variability of total alkalinity (TA) – one major component of the seawater carbonate system – has been constrained by limited historical data collected across the shelf, and the consensus has been that TA is largely conservative.
Ocean acidification driven by absorption of anthropogenic carbon dioxide (CO2) from the atmosphere is now recognized as a systemic, global process that could threaten diverse marine ecosystems and a number of commercially important species. The change in calcium carbonate (CaCO3) mineral saturation states (omega) brought on by the reduction of seawater pH is most pronounced in high latitude regions where unique biogeochemical processes create an environment more susceptible to the suppression of omega values for aragonite and calcite, which are critical to shell building organisms.
This investigation reports, for the first time, results of CO2 system variables in the Gulf of Tehuantepec, located in the Mexican tropical Pacific. We quantified the post-Tehuano concentration of dissolved inorganic carbon (DIC) and pH (April 2013). These values were used to calculate pCO2, aragonite saturation ($Ømega$Ar), and air-sea CO2 fluxes (FCO2). The intense vertical stratification was found to contribute to the biogeochemical processes in surface waters (\textless70 m).