Furthermore, the disparity between fluorescent and O2 flux measurement is not solved by reference to respiration rates (Rdark or Light-enhanced dark respiration, results not shown for the latter) as they follow a similar trend as Pnmax and Pgross. C. implexa grew profusely under November-PI conditions,

but, Pnmax was greatest under November-A1FI conditions. An uncoupling between biomass accumulation and growth rate has been observed in other studies (e.g., Israel et al. 1999 and Xu and Gao 2012) and in at least one species this has been attributed to changes in carbon allocation (Gordillo et al. 2001). Likewise, changes in resource allocation may have occurred in C. implexa, where Rdark tended to be greater under November-A1FI, suggesting that much of the carbon accumulated by day is respired by night, as opposed to converted into biomass for growth. Furthermore, see more there is a tendency for the amount of carbon per dry weight of tissue to be less in the PI and present-day treatments than in the B1 or A1FI treatments, suggesting a bias against the formation of carbon storage compounds such as laminarin and fatty acids (Michel et al. 2010, Gardner et al. 2013). This bias is especially noticeable in the contrast between nutrient-enriched

versus ambient treatments. In this case, algal tissue from enriched treatments, irrespective of experimental time point or scenario, are relatively deplete in carbon and enriched in both Neratinib ic50 nitrogen and phosphorus, clearly demonstrating that the enrichment was assimilated by the algae, even if it did not lead to differential

growth. The reduction in tissue carbon content observed under nutrient addition may have been caused by its release as dissolved organic carbon; this has been suggested for various other tropical algal species under seasonal nutrient enrichment (Wild et al. 2008). The nitrogen assimilated into the tissue of C. implexa can be stored as inorganic nitrogen, used medchemexpress in nitrogen rich pigments such as Chl a, or amino acids and proteins (Chapman and Craigie 1977, Wheeler and North 1980, Bird et al. 1982). The present results suggest that the additional nitrogen is not used for Chl a synthesis in C. implexa because (i) no increase was observed with nutrient addition and (ii) winter Chl a concentration decreased under nutrient addition. This leaves proteins, amino acids, and inorganic nitrogen storage as possible nutrient sinks. The relative xanthophyll pool, that does not include nitrogen as a component, increased with nutrient enrichment, but this response was principally driven by the reduction in Chl a levels, rather than an increase in xanthophyll synthesis. Interestingly, neither reduction in Chl a nor the increase in the relative xanthophyll pool appeared to have consistent effects on either dark-adapted Fv/Fm or Pnmax.