Table 2. Exoskeleton thickness, mineral composition, and mechanical properties.
| Segment | Exposure period | Treatment | Thickness* | Ca (wt. %) | Mg (wt. %) | Ca:Mg | Hardness (GPa) | Stiffness (GPa) |
|---|---|---|---|---|---|---|---|---|
| merus | 3 months | ambient | 8.62 ± 1.34 (N = 6) | 35.38 ± 6.52 (N = 6) | 2.86 ± 0.25 (N = 6) | 12.47 ± 2.80 (N = 6) | 0.48 ± 0.03 (N = 7) | 6.41 ± 0.48 (N = 7) |
| reduced pH | 9.91 ± 1.6 (N = 8) | 41.13 ± 10.47 (N = 7) | 2.99 ± 0.71 (N = 7) | 14.50 ± 5.14 (N = 7) | 0.49 ± 0.02 (N = 8) | 4.98 ± 0.73 (N = 8) | ||
| reduced pH/increased temp | 9.21 ± 0.72 (N = 7) | 34.74 ± 1.96 (N = 6) | 2.83 ± 0.33 (N = 6) | 12.43 ± 1.52 (N = 6) | 0.47 ± 0.07 (N = 8) | 4.14 ± 0.92 (N = 8) | ||
| 6 months | ambient | 9.41 ± 1.36 (N = 12) | 46.46 ± 6.19 (N = 11) | 2.62 ± 0.58 (N = 11) | 19.03 ± 7.52 (N = 11) | 0.51 ± 0.07 (N = 12) | 5.18 ± 1.07 (N = 12) | |
| reduced pH | 9.38 ± 2.22 (N = 11) | 44.28 ± 5.21 (N = 11) | 3.37 ± 0.81 (N = 11) | 13.90 ± 3.68 (N = 11) | 0.51 ± 0.05 (N = 10) | 4.52 ± 0.19 (N = 10) | ||
| reduced pH/increased temp | 9.20 ± 1.70 (N = 12) | 46.84 ± 7.18 (N = 12) | 2.57 ± 0.51 (N = 12) | 19.16 ± 5.70 (N = 12) | 0.57 ± 0.07 (N = 11) | 6.70 ± 1.38 (N = 11) | ||
| carapace | 3 months | ambient | 9.84 ± 1.66 (N = 8) | 37.67 ± 5.73 (N = 6) | 2.36 ± 0.42 (N = 6) | 16.61 ± 5.51 (N = 6) | 0.38 ± 0.02 (N = 8) | 6.12 ± 0.24 (N = 8) |
| reduced pH | 11.84 ± 1.57 (N = 6) | 35.54 ± 3.93 (N = 5) | 2.95 ± 0.71 (N = 5) | 12.93 ± 4.69 (N = 5) | 0.39 ± 0.05 (N = 7) | 2.99 ± 0.79 (N = 7) | ||
| reduced pH/increased temp | 10.54 ± 1.54 (N = 7) | 32.95 ± 6.50 (N = 7) | 2.52 ± 0.51 (N = 7) | 13.75 ± 4.48 (N = 7) | 0.43 ± 0.05 (N = 8) | 5.62 ± 0.67 (N = 8) | ||
| 6 months | ambient | 9.94 ± 1.11 (N = 12) | 41.33 ± 8.32 (N = 11) | 3.01 ± 0.61 (N = 11) | 14.37 ± 4.61 (N = 11) | 0.48 ± 0.09 (N = 10) | 6.84 ± 0.80 (N = 10) | |
| reduced pH | 10.57 ± 2.38 (N = 11) | 39.16 ± 7.13 (N = 11) | 3.18 ± 0.60 (N = 11) | 12.64 ± 2.94 (N = 11) | 0.55 ± 0.09 (N = 11) | 10.18 ± 1.32 (N = 11) | ||
| reduced pH/increased temp | 10.95 ± 1.94 (N = 11) | 40.41 ± 6.69 (N = 12) | 3.04 ± 0.70 (N = 12) | 13.80 ± 3.56 (N = 12) | 0.51 ± 0.05 (N = 11) | 8.62 ± 0.83 (N = 11) |
Values are mean ± standard deviation. N = number of individuals. Bold values indicate significant difference between treatments (see text for statistics). Values in italics indicate significant difference between exposure periods within treatments (α = 0.05). *Thickness is unitless, as it was corrected for body size by dividing values by carapace length.