How will phytoplankton respond to the rising partial pressure of atmospheric CO2 and resulting ocean acidification? A study from the Plymouth Marine Laboratory (Plymouth, UK) and the University of Essex (Colchester, UK) investigated the question.
The Study: 2017 pCO2 concentration compared to projected 2100 pCO2 concentration
Keys et al. (2017) studied the effects of elevated pCO2 on Phaeocystis spp. spring bloom growth during a fifteen-day microcosm experiment. Natural phytoplankton community samples were collected from station L4 in the western English Channel. These populations were then incubated in seawater media with ambient pCO2 concentrations (as measured at station L4 during collection) and elevated pCO2 concentrations (as projected for the end of year 2100). Keys et al. utilized the FlowCam for phytoplankton community analysis for the 18 to 100 µm size fraction. Population factors, such as relative type percentages and biomass, were compared to the 21-year study of phytoplankton community structure collected from station L4.
The Results: Increased growth & dominance
Phaeocystis spp. subjected to elevated pCO2 increased carbon biomass by 330% during the 15-day period and comprised 70% of the total phytoplankton biomass. This study suggests that elevated pCO2 concentrations may result in future Phaeocystis spp. dominance.
The Implications: Ecosystem disruption and marine mortality
Phaeocystis spp. blooms can have adverse effects on marine ecosystems, food web structures, fisheries, and coastal regional tourism. Fish and shellfish mortality, inhibition of copepod grazing, negative effects on diatom growth, and anoxic conditions on surface sediment in coastal regions are all possible side effects of a dense Phaeocystis spp. bloom.
This study was published in Harmful Algae v. 62 pp.92-106. Access the original text here.
Keys, M., Tilstone, G., Findlay, H.S., Widdicombe, C.E., and T. Lawson, (2017), Effects of elevated CO2 on phytoplankton community biomass and species composition during a spring Phaeocystis spp. bloom in the western English Channel, Harmful Algae, v. 67, pp 92-106.