Objectives and Hypotheses

The overal aim of this project is to obtain a quantitative understanding of the impact of  Ocean Acidification on the surface ocean biology and ecosystem, and the role of the surface ocean within the overall Earth System.

Our high-level objectives are:

  1. To ascertain the impact of OA on planktonic organisms (in terms of physiological impacts, morphology, population abundances and community compasition).
  2. To quantify the impacts of OA on biogeochemical processes affecting the ocean carbon cycle (both directly and indirectly, such as via availablitity of biolimiting nutrients).
  3. To quantify the impacts of OA on the sir-sea flux of climate active gases (DMS and N2O in particular.

The primary hypotheses which will test are:

(H1)   A decline in pH and  ΩCaCO3 as a result of rising atmospheric CO2 concentrations will  affect  the rate and quality of formation of  CaCO3 shells by planktonic calcifiers.

(H2) Carbonate chemistry changes will influence biogeochemical rates per unit biomass, such as photosynthesis, respiration, calcification and nitrification.

(H3)  Community structure will change and calcifying organisms will make up less of the total community (and consist of less strongly calcified genotypes) under lower pH /ΩCaCO3 conditions.

(H4)   OA will impact on climate through reductions in ballasting by CaCO3 production of albedo-altering DMS and production of the greenhouse gas N2O .

 (H5)   High CO2 will alter zooplankton:phytoplankton and phytoplankton:bacteria ratios through production of increasingly carbon-rich particulate and dissolved organics (food quality and DOC).

(H6)   Some place-to-place differences in in-situ parameters are due to carbonate chemistry gradients rather than to alternative environmental gradients.