We now know that there are similar effects of both sources of acidification on aquatic organisms, namely marine invertebrates. We must however be cautious when matching such effects when the underlying response-mechanisms (such as physiological pathways, or gene expression) of organisms are not fully understood.

On the other hand, the study of the effects of estuarine acidification may help us scale up from the laboratory-based studies that, so far, characterize the investigation on the ocean acidification topic. In other words, with the proper background, we might be able to use already-observed responses of organisms to estuarine-acidification to predict ecosystem-scale effects of ocean acidification.

I've been working on this subject myself and you might find the following papers useful:

Amaral V, Cabral HN, Bishop MJ (2011) Resistance among wild invertebrate populations to recurrent estuarine acidification. Estuar Coast Shelf Sci 93: 460-467, doi:10.1016/j.ecss.2011.05.024

Amaral V, Cabral HN, Bishop MJ (2012) Effects of estuarine acidification on predatory-prey interactions. Mar Ecol Prog Ser 445: 117-127, doi:10.3354/meps09487

Amaral V, Thompson EL, Raftos DA (2012) The proteomes of Sydney rock oysters vary spatially according to exposure to acid sulfate runoff. Mar Freshw Res 63: 361-369, doi:10.1071/MF11213

Rather than directly comparing the two issues, it is still valid to use both as indicators or analogues of the same acidification issue. In any case, there are strong arguments to support that estuarine acidification contributes to coastal ocean acidification. Good question though.

Estuarine acidification is a more complex issue than ocean acidification, because estuaries have more environmental variability, and thus more variability in pH. Please remember that pH is not the concentration of H+ ions, but the activity of these ions, and activity is a function of both temperature and salinity. Both variables change quite a bit in estuaries.

Ocean acidification and "estuarine acidification" are just two different mechanisms that can add-up in estuarine (coastal) systems. In estuaries a lot of organic matter is transported from the rivers to the coastal sea. The organic matter is degraded by organisms consuming the oxygen and producing CO2 that subsequently acidifies the seawater. This effect can add up on ocean acidification - especially in upwhelling situations. (read: Melzner et al (2012) Future ocean acidification

will be amplified by hypoxia in coastal habitats. Mar Biol

Published online: 29 May 2012. doi:10.1007/s00227-012-1954-1)

We now know that there are similar effects of both sources of acidification on aquatic organisms, namely marine invertebrates. We must however be cautious when matching such effects when the underlying response-mechanisms (such as physiological pathways, or gene expression) of organisms are not fully understood.

On the other hand, the study of the effects of estuarine acidification may help us scale up from the laboratory-based studies that, so far, characterize the investigation on the ocean acidification topic. In other words, with the proper background, we might be able to use already-observed responses of organisms to estuarine-acidification to predict ecosystem-scale effects of ocean acidification.

I've been working on this subject myself and you might find the following papers useful:

Amaral V, Cabral HN, Bishop MJ (2011) Resistance among wild invertebrate populations to recurrent estuarine acidification. Estuar Coast Shelf Sci 93: 460-467, doi:10.1016/j.ecss.2011.05.024

Amaral V, Cabral HN, Bishop MJ (2012) Effects of estuarine acidification on predatory-prey interactions. Mar Ecol Prog Ser 445: 117-127, doi:10.3354/meps09487

Amaral V, Thompson EL, Raftos DA (2012) The proteomes of Sydney rock oysters vary spatially according to exposure to acid sulfate runoff. Mar Freshw Res 63: 361-369, doi:10.1071/MF11213

As a few of the above replies indicate, the effects of pH at the molecular/physiological level are going to be the same in an open ocean scenario and an estuarine one. As with much of what is observed in estuaries, the drivers behind any observed change or fluctuation in pH of estuarine waters (or really even near coastal waters I'd wager) are more numerous and have both anthropogenic and natural origins. Furthermore, detecting a biological effect is going to be different in estuarine organisms, which are typically more tolerant of fluctuating environmental conditions than their truly marine counterparts.

That said, one could theoretically track the influence of increased atmospheric CO2 on estuarine pH, as long as one controls for things like salinity, depth, residence time, general state of autotrophy/heterotrophy, turbidity, catchment geology, etc. It might be more interesting to think about it from the P-CO2 perspective, DIC signatures, and the like.

Your question has been mostly answered by comments above. I just want to add that there is a nice paper by Feely et al. (2010) which is a good (quantitative) example of the potential importance of "internal" (estuarine) processes like remineralization vs. "anthropogenic" acidification.

Feely et al. (2010). The combined effects of ocean acidification, mixing, and respiration on pH and carbonate saturation in an urbanized estuary. Estuarine, Coastal and Shelf Science 88: 442-449.

In an estuarine case with which I have some knowledge a 'violent' drop in estuarine pH created an environment barren for foraminifera for over a year but the on-going records of test deformation in foraminifera is (probably) due to heavy metal contamination and not the result of pH fluctuations. Presently writing this work up for publication.

Definitely there are variability in acidification in estuarine and open ocean, in the former not only the environment but also various other industrial and domestic discharge (if any), water level, rainfall, and various other factors plays atleast part of the role., the fluctuation here is very high.,

Oceanic acidification when compared to Estuarine acidification its mainly due to stream suspended sediments low mostly composed on sand. Affected waters are characterized by low pH and elevated concentrations of metals, particularly iron, aluminum, and manganese. So Estuarine is more acidified when compared to ocean.

Yes of course why not it is comparable because many of the factors are intercomparable.

Yes, I think we can compare both of the systems, you can check the carbonate salt (calcium and magnesium or divalent cation) in both system that very highly effect to both systems. Because the acidification source in the water in form of carbonate. The carbonate salt become the major indicator to measure the acid in both system........

Dear Belal

Some recent reports have indicated that the consequences of ocean acidification will play havoc in estuaries as well but perhaps have a different outcome from that of the open ocean. A study estimated that pH of estuarine water in a North American estuary is decreasing at a rate of 0.05-0.15 units since the last decade. Further, acidified coastal waters upwelling along the continental margins may enter into the estuarine systems affecting the ecosystem dynamics in the estuaries. Following literature may add to our conception.

1. Feely, R.A., Sabine, C.L., Hernandez-Ayon, J.M., Ianson, D., Hales, B., 2008. Evidence for upwelling of corrosive “acidified” water onto the continental shelf. Science 320, 1490-1492.

2. Doney, S.C., Mahowald, N., Lima, I., Feely, R.A., Mackenzie, F.T., Lamarque, J.F., Rasch, P.J., 2007. Impact of anthropogenic atmospheric nitrogen and sulfur deposition on ocean acidification and the inorganic carbon system. Proceedings of the National Academy of Sciences of the United States of America 104, 14580-14585.

3. Sabine, C.L., Feely, R.A., Gruber, N., Key, R.M., Lee, K., Bullister, J.L., Wanninkhof, R., Wong, C.S., Wallace, D.W.R., Tilbrook, B., Millero, F.J., Peng, T.H., Kozyr, A., Ono, T., Rios, A.F., 2004. The oceanic sink for anthropogenic CO2. Science 305, 367-371.

4. http://faculty.wwu.edu/~shulld/ESCI%20432/Feely2010.pdf

Best

Dola