Initial composition and abundance of phytoplankton and microzooplankton.

<p>Top panel: The relative contribution of each of the five main phytoplankton groups in the WAP region to total chlorophyll <i>a</i> in the top 50 m of the water column (WC_{0–50 m}) where seawater and krill were collected for the experimental incubations (HPLC pigment CHEMTAX analysis; % contribution to total chlorophyll <i>a</i>). Bottom panel: Abundance of dominant phytoplankton (cryptophytes, diatoms) and microzooplankton (ciliates) in incubation bottles after a 24-hour acclimation period (T₀) in control (no krill added) bottles bubbled with ambient (Amb) and high concentrations of CO₂ (Microscopic analysis; cells ml⁻¹). Values are mean±1 SD.