Ocean acidification increases the accumulation of toxic phenolic compounds across trophic levels

Abstract

Increasing atmospheric CO2 concentrations are causing ocean acidification (OA), altering carbonate chemistry with consequences for marine organisms. Here we show that OA increases by 46–212% the production of phenolic compounds in phytoplankton grown under the elevated CO2 concentrations projected for the end of this century, compared with the ambient CO2 level. At the same time, mitochondrial respiration rate is enhanced under elevated CO2 concentrations by 130–160% in a single species or mixed phytoplankton assemblage. When fed with phytoplankton cells grown under OA, zooplankton assemblages have significantly higher phenolic compound content, by about 28–48%. The functional consequences of the increased accumulation of toxic phenolic compounds in primary and secondary producers have the potential to have profound consequences for marine ecosystem and seafood quality, with the possibility that fishery industries could be influenced as a result of progressive ocean changes.

Interactive network configuration maintains bacterioplankton community structure under elevated CO<sub>2</sub> in a eutrophic coastal mesocosm experiment

“…Differences in bacterioplankton community diversity between the HC and LC treatments were also not remarkable. These results suggest the possibility that the whole bacterioplankton community has a certain degree of resilience to elevated CO 2 , which is consistent with a previous stated hypothesis (Joint et al, 2011).…”

“…Furthermore, marine bacterioplankton play an essential role in marine ecosystems and global biogeochemical cycles central to the biological chemistry of Earth (Falkowski et al, 2008). The null hypothesis is that elevated CO 2 will not affect biogeochemical processes (Liu et al, 2010;Joint et al, 2011); however, more investigation is required to adequately test this. Ocean acidification mesocosm experiments provide good opportunities to explore the responses of marine bacteria to elevated CO 2 .…”

“…In this way, we were able to investigate the effect of ocean acidification on phytoplankton and bacterioplankton in naturally eutrophic waters while minimizing the complexity of shifting compositions of natural phytoplankton communities. Correlated data about the effects of ocean acidification on the artificial phytoplankton community using the same mesocosm system are available in Jin et al (2015) and Liu et al (2017).…”

Changes in Bioenergetics Associated with Ocean Acidification and Climate Changes

“…Phytoplankton species (diatoms and coccolithorphores) grown under OA accumulate more phenolics within their cells, which lead to higher contents of phenolics in copepods who feed them [9]. This is caused by alterations in metabolic pathways (ß-oxidation and the Krebs cycle) that are considered to provide extra energy to cope with acidic stress under OA treatment (Figure 1).…”

“…This aspect is certainly worth looking into from biochemical and molecular aspects, since degradation of extra phenolic compounds requires more related enzymes or higher activity of them, which then have imprints on expressions of genes. Figure 1: Ocean acidification up-regulated (red) and downregulated (green) metabolic pathways in a calcifying microalga (Emiliania huxleyi) Jin et al [9].…”