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 CO >> 2 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.
