Table 1.
Seawater carbonate chemistry data (mean ± s.e.) and experimental conditions.
Fig 1.
Giant clam shell measurements.
Fluted giant clam Tridacna squamosa juvenile a) with mantle out, and b) and c) showing shell dimensions measured: length (anterior-posterior measurement), height (dorso-ventral measurement), width including ornamentation and width excluding ornamentation.
Fig 2.
Influence of elevated CO2 on giant clam survival at each light level.
Effects of CO2 on juvenile fluted giant clam survival shown by Kaplan-Meier survival trajectories at a) low-light (PAR 35 μmol photons m-2 s-1), b) mid-light (PAR 65 μmol photons m-2 s-1) and c) high-light (PAR 304 μmol photons m-2 s-1). At high-light, survival was 100% so survival trajectories are the same for all CO2 levels.
Fig 3.
Influence of elevated CO2 and light on giant clam growth.
Effects of CO2 and PAR on juvenile fluted giant clam growth in a) total animal mass, b) principle component analysis (PCA) component 1 (i.e. all shell linear dimensions), and individually, c) shell length, d) shell height, e) shell ornamentation width, and f) shell width gains. Numbers of replicates are the same for each graph and are shown above the bars in a). *denotes a significant difference from the control at each light level (for a, c-f). +denotes a significant difference from the PAR 35 control-CO2 level in PCA component 1 (for b). Error bars represent ±1 s.e.
Fig 4.
Conceptual diagram showing the relationship between CO2 and light availability.
Seawater CO2 level (ocean acidification) and light availability influence the likelihood of sub-lethal and lethal effects on juvenile giant clams. This diagram is based on experimental data and is therefore for the range of light levels investigated this study only (PAR 35–304 μmol photons m-2 s-1).