Whereever there are nutrients and light something will grow. There may be some subtle relationships between ocean pH and NPP, perhaps mediated through trace nutrient availability or something like that, but I do not think there is any first order impact of ocean acidification on net primary productivity (NPP).
Ocean acidification is about ecological disturbance and biodiversity and not about NPP. The tendency, on land and ocean, is the ascendancy of weeds. We are disturbing environments. Invasive generalists (i.e., weeds) will benefit and species that are finely tuned to very particular condition will suffer. _______________ Ken Caldeira Carnegie Institution for Science Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 [email protected] http://dge.stanford.edu/labs/caldeiralab https://twitter.com/KenCaldeira On Thu, Nov 28, 2013 at 6:59 PM, Fred Zimmerman <[email protected]>wrote: > How much acidification is required to affect npp? > On Nov 28, 2013 4:04 PM, "Ken Caldeira" <[email protected]> > wrote: > >> Of course, even under rather extreme assumption, changes in planktonic >> productivity can do little to slow the rising tide of ocean acidification. >> (see Cao and Caldeira, 2010 for a relevant study) >> >> The main threat from ocean acidification is not to net primary >> productivity, but rather to biodiversity. >> >> >> _______________ >> Ken Caldeira >> >> Carnegie Institution for Science >> Dept of Global Ecology >> 260 Panama Street, Stanford, CA 94305 USA >> +1 650 704 7212 [email protected] >> http://dge.stanford.edu/labs/caldeiralab >> https://twitter.com/KenCaldeira >> >> >> >> On Thu, Nov 28, 2013 at 8:00 AM, M V Bhaskar <[email protected]>wrote: >> >>> >>> >>> >>> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0079890 >>> Iron Limitation Modulates Ocean Acidification Effects on Southern Ocean >>> Phytoplankton Communities >>> >>> >>> - Clara J. M. Hoppe, >>> - Christel S. Hassler, >>> >>> >>> - Christopher D. Payne, >>> >>> >>> - Philippe D. Tortell, >>> >>> >>> - Björn Rost, >>> >>> >>> - Scarlett Trimborn >>> >>> >>> - Published: Nov 20, 2013 >>> - DOI: 10.1371/journal.pone.0079890 >>> >>> >>> Abstract >>> >>> The potential interactive effects of iron (Fe) limitation and Ocean >>> Acidification in the Southern Ocean (SO) are largely unknown. Here we >>> present results of a long-term incubation experiment investigating the >>> combined effects of CO2 and Fe availability on natural phytoplankton >>> assemblages from the Weddell Sea, Antarctica. Active Chl *a* fluorescence >>> measurements revealed that we successfully cultured phytoplankton under >>> both Fe-depleted and Fe-enriched conditions. Fe treatments had significant >>> effects on photosynthetic efficiency (Fv/Fm; 0.3 for Fe-depleted and >>> 0.5 for Fe-enriched conditions), non-photochemical quenching (NPQ), and >>> relative electron transport rates (rETR). pCO2 treatments significantly >>> affected NPQ and rETR, but had no effect on Fv/Fm. Under Fe limitation, >>> increased pCO2 had no influence on C fixation whereas under Fe >>> enrichment, primary production increased with increasing pCO2 levels. >>> These CO2-dependent changes in productivity under Fe-enriched >>> conditions were accompanied by a pronounced taxonomic shift from weakly to >>> heavily silicified diatoms (i.e. from *Pseudo-nitzschia* sp. to >>> *Fragilariopsis* sp.). Under Fe-depleted conditions, this functional >>> shift was absent and thinly silicified species dominated all pCO2 treatments >>> (*Pseudo-nitzschia* sp. and*Synedropsis* sp. for low and high pCO2, >>> respectively). Our results suggest that Ocean Acidification could increase >>> primary productivity and the abundance of heavily silicified, fast sinking >>> diatoms in Fe-enriched areas, both potentially leading to a stimulation of >>> the biological pump. Over much of the SO, however, Fe limitation could >>> restrict this possible CO2 fertilization effect." >>> >>> >>> regards >>> >>> Bhaskar >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "geoengineering" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/geoengineering. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/geoengineering. >> For more options, visit https://groups.google.com/groups/opt_out. >> > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/groups/opt_out.
