The formation of calcareous skeletons by marine planktonic organisms and their subsequent sinking to depth generates a continuous rain of calcium carbonate to the deep ocean and underlying sediments1 This is important in regulating marine carbon cycling and ocean–atmosphere CO2 exchange2 The present rise in atmospheric CO2 levels3 causes significant changes in surface ocean pH and carbonate chemistry4 Such changes have been shown to slow down calcification in corals and coralline macroalgae5,6, but the majority of marine calcification occurs in planktonic organisms Here we report reduced calcite production at increased CO2 concentrations in monospecific cultures of two dominant marine calcifying phytoplankton species, the coccolithophorids Emiliania huxleyi and Gephyrocapsa oceanica  This was accompanied by an increased proportion of malformed coccoliths and incomplete coccospheres Diminished calcification led to a reduction in the ratio of calcite precipitation to organic matter production Similar results were obtained in incubations of natural plankton assemblages from the north Pacific ocean when exposed to experimentally elevated CO2 levels We suggest that the progressive increase in atmospheric CO2 concentrations may therefore slow down the production of calcium carbonate in the surface ocean As the process of calcification releases CO2 to the atmosphere, the response observed here could potentially act as a negative feedback on atmospheric CO2 levels

/pdf/reduced-calcification-of-marine-plankton-in-response-to-43ko7hu336.pdf

Reduced calcification of marine plankton in response to increased atmospheric CO2.

The collection of extensive, reliable, oceanic carbon data is a key component of the Joint Global Ocean Flux Study (JGOFS). A portion of the US JGOFS oceanic carbon dioxide measurements will be made during the World Ocean Circulation Experiment Hydrographic Program. A science team has been formed to plan and coordinate the various activities needed to produce high quality oceanic carbon dioxide measurements under this program. This handbook was prepared at the request of, and with the active participation of, that science team. The procedures have been agreed on by the members of the science team and describe well tested methods. They are intended to provide standard operating procedures, together with an appropriate quality control plan, for measurements made as part of this survey. These are not the only measurement techniques in use for the parameters of the oceanic carbon system; however, they do represent the current state-of-the-art for ship-board measurements. In the end, the editors hope that this handbook can serve widely as a clear and unambiguous guide to other investigators who are setting up to analyze the various parameters of the carbon dioxide system in sea water.

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Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water. Version 2

Thermodynamics of the carbon dioxide system in the oceans

Eutrophication is one of the most severe and widespread forms of disturbance affecting coastal marine systems. Whilst there are general models of effects on benthos, such as the Pearson-Rosenberg (P-R) model, the models are descriptive rather than predictive. Here we first review the process of increased organic matter production and the ensuing sedimentation to the seafloor. It is shown that there is no simple relationship between nutrient inputs and the vertical flux of particulate organic matter (POM). In particular, episodic hydrographic events are thought to be the key factor leading to high rates of sedimentation and accompanying hypoxia. We extend an earlier review of effects of hypoxia to include organisms living in the water column. In general, fishes are more sensitive to hypoxia than crustaceans and echinoderms, which in turn are more sensitive than annelids, whilst molluscs are the least sensitive. Growth is affected at oxygen concentrations between 6.0 and 4.5 mg O 2 l -1 , other aspects of metabolism are affected at between 4 and 2 mg O 2 l -1 and mortality occurs where concentrations are below 2.0 to 0.5 mg O 2 l -1 . Field studies, however, show that complex behavioural changes also occur as hypoxia increases, and these are described herein. The areas where hypoxia occurs are frequently areas that are stagnant or with poor water exchange. Thus again, hydrographic factors are key processes determining whether or not hypoxia and eutrophication occur. Tolerance to ammonia and hydrogen sulphide is also reviewed, as these substances are found at near zero concentrations of oxygen and are highly toxic to most organisms. However, the effects of interactions between oxygen, ammonia and hydrogen sulphide only occur below oxygen concentrations of ca. 0.5 mg O 2 l -1 , since only below this concentration are hydrogen sulphide and oxygen released into the water. Models of eutrophication and the generation of hypoxia are discussed, and in particular the P-R model is analysed. Although agreement with the model is widely reported the actual predictions of the model have rarely been tested. Our review suggests that the major effects on benthic fauna result from hypoxia rather than organic enrichment per se and suggests that the P-R model is descriptive rather than predictive. Finally, a managerial tool is proposed, based on the stages of effects of hypoxia and organic enrichment suggested by the P-R model and on an earlier study. The proposed strategy involves rapid assessment tools and indicates where more detailed surveys are needed. Managers are advised that remedial action will not produce rapid results and that recovery from eutrophication will probably take decades. Thus it is essential to detect potential hypoxia and eutrophication effects at early stages of development.

/pdf/effects-of-hypoxia-and-organic-enrichment-on-the-coastal-1vdtes434o.pdf

Effects of hypoxia and organic enrichment on the coastal marine environment

https://www.whoi.edu/science/MCG/groundwater/pubs/PDF/burnett%20et%20al..pdf

Quantifying Submarine Groundwater Discharge in the Coastal Zone via Multiple Methods

Waterborne nutrients enter Great Sippewissctt Marsh through groundwater, rain, and tidal flooding. The ebb of tidal water removes nutrients. During summer, uptake by marsh biota leads to net import of nutrients. The increased export of ammonium in August may be due to leaching from senescent marsh plants. There is a net annual export of ammonium, nitrate, nitrite, dissolved organic (DON) and particulate (PN) nitrogen, particulate carbon (PC), and phosphate. Ammonium, DON, and PN are the major forms of nitrogen exported. Nutrient concentrations in coastal and marsh water are correlated, and marsh exports could contribute substantially to nutrient supplies of coastal waters. Groundwater entering the marsh provides primarily N03-N and DON. Nutrient inputs through precipitation consist primarily of DON, NO,-N, and NIIcN. Particulate materials in rain have a high C:N ratio, contributing little to enrichment of the nitrogen-limited salt marsh. Groundwater carries over 20 times the amount of nutrients brought in by rain. The nitrogen provided by both sources is more than enough to support annual plant growth. Inputs of nitrogen by groundwater are therefore important to the nitrogen economy of a salt marsh. About half the dissolved inorganic nitrogen brought into the marsh by groundwater is converted to and exported as PN. The marsh thus transforms the nitrogen that would have been used by primary producers into a form suitable for consumers such as shellfish. Large amounts of apparently refractory DON enter the marsh in groundwater and similar amounts are exported by tides. PC exported to coastal water is equivalent to 40% of the net annual production of Spartina alterniflora, the dominant marsh plant.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1978.23.4.0798

Nutrient and particulate fluxes in a salt marsh ecosystem: Tidal exchanges and inputs by precipitation and groundwater 1

Measurements of total carbon dioxide and alkalinity by potentiometric titration in the GEOSECS program

At frequencies below 1 kHz, sound absorption coefficients in the ocean are a function of pH, and at higher frequencies they are dependent upon MgSO4. The pH dependent terms are attributable to relaxation of B(OH)3 and MgCO3 species, and the ensemble effect has been approximated (Mellen et al., 1987a) as α = α1(MgSO4) + α2(B(OH)3) + α3(MgCO3), where α is the absorption coefficient in decibels per kilometer, and αn = (S/35)An[ƒ2ƒn/(ƒ2 + ƒn2)], where S is the salinity, An is the amplitude of each component and depends on pH, ƒ is the frequency, and ƒn is the relaxation frequency. Overall accuracy of ±15% in a requires that pH be known to 0.05 pH units. The presently used oceanic pH field for sound absorption models is derived from a combination of Geochemical Ocean Sections Study (GEOSECS) data and Soviet data from the 1978 Gorshkov atlas for the North Atlantic where GEOSECS data are absent. We compare the North Atlantic fields with the well-constrained Transient Tracers in the Ocean North Atlantic CO2 data set and find large differences. We further show that sufficiently strong correlations exist between CO2 system variables and other more commonly available hydrographic properties and that improved renditions of the pH field in other regions of the ocean are possible once equivalent local correlations are established, thus leading to greatly improved estimates of the sound absorption field.

Deborah K. Shafer

Papers

Nutrient and particulate fluxes in a salt marsh ecosystem: Tidal exchanges and inputs by precipitation and groundwater 1

Measurements of total carbon dioxide and alkalinity by potentiometric titration in the GEOSECS program

The pH of the North Atlantic Ocean: improvements to the global model for sound absorption in seawater

The pH of the North Atlantic Ocean: Improvements to the global model for sound absorption in seawater

Temperature dependence of CO2 fugacity in seawater