Working with two previously untested coccolithophores, Calcidiscus leptoporus and Coccolithus pelagicus, which they describe as "two of the most productive marine calcifying species," Langer et al. (2006) conducted batch-culture experiments in which they observed (1) a "deterioration of coccolith production above as well as below present-day CO2 concentrations in C. leptoporus [italics added]," and (2) a "lack of a CO2 sensitivity of calcification in C. pelagicus" over an atmospheric CO2 concentration range of 98-915 ppm, both of which observations, in their words, "refute the notion of a linear relationship of calcification with the carbonate ion concentration and carbonate saturation state."

In an apparent negative finding, however, particularly in the case of C. leptoporus, Langer et al. observed that although their experiments revealed that "at 360 ppm CO2 most coccoliths show normal morphology," they found that at both "higher and lower CO2 concentrations the proportion of coccoliths showing incomplete growth and malformation increases notably [italics added]."

To determine if such was also the case in the real world, the researchers studied coccolith morphologies in six sediment cores extracted along a range of latitudes in the Atlantic Ocean. As they describe it, this work revealed that changes in coccolith morphology similar to those "occurring in response to the abrupt CO2 perturbation applied in our experimental treatments are not mirrored in the sedimentary record," which finding indicates, as they suggest, that "in the natural environment C. leptoporus has adjusted to the 80 ppm CO2 and 180 ppm CO2 difference between present, preindustrial and glacial times, respectively."

In further discussing these observations, the team of seven scientists from Germany and the United Kingdom say "it is reasonable to assume that C. leptoporus has adapted its calcification mechanism to the change in carbonate chemistry having occurred since the last glacial maximum," suggesting as a possible explanation for this phenomenon that "the population is genetically diverse, containing strains with diverse physiological and genetic traits, as already demonstrated for E. huxleyi (Brand, 1981, 1982, 1984; Conte et al., 1998; Medlin et al., 1996; Paasche, 2002; Stolte et al., 2000)." They also state that this adaptive ability "is not likely to be confined to C. leptoporus but can be assumed to play a role in other coccolithophore species as well," which leads them to conclude that such populations "may be able to evolve so that the optimal CO2 level for calcification of the species tracks the environmental value." Regarding the future, therefore, Langer et al. end on an extremely positive note, stating that "genetic diversity, both between and within species, may allow calcifying organisms to prevail in a high CO2 ocean."

In a somewhat similar study, Feng et al. (2008) grew the marine coccolithophore Emiliania huxleyi -- which they isolated from the Sargasso Sea -- by semi-continuous culture methods at two different (low, high) light intensities (50 and 400 µmol photons/m²/sec), two different (low, high) temperatures (20 and 24°C), and two different (low, high) CO2 concentrations (375 and 750 ppm); and in doing so, they found that in the low-light environment, the chlorophyll a-normalized photosynthetic rates of the coccolithophores in all four temperature/CO2 treatments attained maximum values at an irradiance of approximately 200 µmol photons/m²/sec, where the maximum rate was lowest in the low-temperature, low-CO2 or ambient treatment, but was significantly increased by 55% by elevated temperature alone and by 95% by elevated CO2 alone, while in the high-temperature, high-CO2 or greenhouse treatment it was increased by 150% relative to the ambient treatment.

In the high-light environment, on the other hand, the chlorophyll a-normalized photosynthetic rates did not max out below the maximum irradiance tested (900 µmol photons/m²/sec) for any but the ambient treatment. Consequently, the equations fit to the data of the other treatments were extrapolated to their respective photosynthetic maxima, which produced corresponding maximum photosynthetic rate increases of 58%, 67% and 92% for the elevated temperature alone, elevated CO2 alone and greenhouse treatments, respectively. Last of all, in the high-light greenhouse treatment characteristic of the future, the maximum photosynthetic rate was found to be 178% greater than what it was in the low-light ambient treatment characteristic of the present. Thus, the seven researchers say their results suggest that "future trends of CO2 enrichment, sea-surface warming and exposure to higher mean irradiances from intensified [surface water] stratification will have a large influence on the growth of Emiliania huxleyi." And, of course, that "large influence" will most likely be positive, based on the impressive results of their experiment.

Also working with Emiliania huxleyi, Iglesias-Rodriguez et al. (2008) grew several batch incubations of this coccolithophore species in the laboratory, while bubbling air of a number of different atmospheric CO2 concentrations through the culture medium and determining the amounts of particulate inorganic carbon (PIC) and particulate organic carbon (POC) produced by the coccolithophores within the different CO2 treatments. In addition, they determined the change in average coccolithophore mass over the past 220 years in the real world of nature, based on data they obtained from a sediment core extracted from the subpolar North Atlantic Ocean, over which period of time the air's CO2 concentration rose by approximately 90 ppm. And as a result of their efforts, the thirteen researchers -- hailing from the United Kingdom, France and the United States -- observed an approximate doubling of both PIC and POC between the culture media in equilibrium with air of today's CO2 concentration and air of 750 ppm CO2. In addition, they found that the field evidence obtained from the deep-ocean sediment core they studied "is consistent with these laboratory conclusions, indicating that over the past 220 years there has been a 40% increase in average coccolith mass."

Working with the same sediment core, Halloran et al. (2008) analyzed the size distribution of CaCO3 particles in the less-than-10-µm sediment fraction over the past quarter-century. This work revealed, as they describe it, "a changing particle volume since the late 20th century consistent with an increase in the mass of coccoliths produced by the larger coccolithophore species," leading them to conclude that "in the real ocean the larger coccolithophore species increase their calcification in response to anthropogenic CO2 release [italics added]," contrary to what typically occurs in the lifeless "virtual ocean" of theoreticians who see bad consequences in nearly everything that could possibly be related to the historical rise in the air's CO2 concentration. In addition, the four researchers state that this positive calcification response "could be attributed to an alleviation of CO2 limitation in species that partly rely on the diffusive supply of dissolved carbon dioxide for photosynthesis, as demonstrated by a rise in photosynthetic efficiency with increasing carbon dioxide in cultures of E. huxleyi (Rost et al., 2003)."

In introducing their study of the subject, Grelaud et al. (2009) say that "in the context of modern global warming and ocean acidification due to anthropogenic CO2 release," they "investigated the morphometry (size, weight) of selected species of the order Isochrysidales (i.e., E. huxleyi, G. muellerae and G. oceanica) to understand how coccolithophores' carbonate mass is influenced by recent oceanographic global changes." This they did via analyses of sediment cores taken from "the deep center of the Santa Barbara Basin (SBB) on the North American Pacific margin in the interval from AD 1917 to 2004," finding that "morphometric parameters measured on E. Huxleyi, G. muellerae and G. oceanica indicate increasing coccolithophore shell carbonate mass from ~1917 until 2004 concomitant with rising pCO2 and sea surface temperature in the region of the SBB [italics added]." More specifically, they note that "a >33% increase in mean coccolith weight was determined for the order Isochrysidales over 87 years from ~1917 until 2004."

In describing the significance of their results, the three researchers write that "the last century has witnessed an increasing net influx of atmospheric carbon dioxide into the world's oceans, a rising of pCO2 of surface waters, and under-saturation with respect to aragonite, especially along the North American Pacific margin," which was the site of their study. These conditions, as they describe it, have been predicted by climate alarmists "to result in reduced coccolithophore carbonate mass and a concomitant decrease in size and weight of coccoliths [italics added]." As indicated by what they discovered, however, just the opposite appears to be the case in the real world, even in places where the predicted calcification reductions are expected to be greatest.

Last of all, writing in the Journal Club section of Nature, Stoll (2009) restates the climate-alarmist mantra that "ocean acidification in response to excess carbon dioxide in the atmosphere could become a problem for marine organisms, especially those that make skeletons or shells out of calcium carbonate," including "the coccolithophorids -- microscopic algae that are, by volume, the most important shell producers." However, she has a much more optimistic view of the subject, thanks in large part to the recent research of Langer et al. (2009).

The latter scientists -- hailing from France, Germany, Spain and the Netherlands -- grew four different strains of the coccolithophore Emiliania huxleyi in dilute batch cultures of seawater with carbonate chemistries characteristic of those expected to prevail beneath an atmosphere with CO2 concentrations ranging from approximately 200 to 1200 ppm, while they measured particulate organic carbon content, particulate inorganic carbon content, and organic and inorganic carbon production. By these means, they found that the four strains "did not show a uniform response to carbonate chemistry changes in any of the analyzed parameters and none of the four strains displayed a response pattern previously described for this species." In light of these findings, therefore, plus other aspects of their earlier studies (Langer et al. 2006, 2007) and the diverse findings of others (all of whom had used still different strains of the species), the five scientists concluded that "the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis."

Stoll agrees with this assessment, stating that Langer et al. "argue convincingly" in this regard; and she adds that the work of those who foresee disastrous consequences typically "precludes the kind of natural selection and adaptation that might occur over decades and centuries in the ocean." And in further discussing the subject, Langer et al. (2009) write that "shifts in dominance between species and/or between clones within a species might therefore be expected," as the air's CO2 content continues to rise; but they say that far too often "the possibility of adaptation is not taken into account."

This ought not be, for the great genetic diversity that exists, both among and within species, in the words of Stoll, "is good insurance in a changing ocean." Indeed, we interpret it as evidence that earth's coccolithophorids are well prepared for whatever the future may thrust at them in this regard, for as Langer et al. (2006) have more boldly and explicitly stated, "genetic diversity, both between and within species, may allow calcifying organisms to prevail in a high CO2 ocean," which does, in fact, appear to be the consensus of most studies that have moved from the initial state of theoretical speculation to the intermediate crucible of laboratory experimentation to the final field work of real-world observation.

References
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