Table 1.

Morpholo-physiological characteristics of normoxia-acclimated and hypoxia-acclimated animals

Animal acclimation group Dependence
ParameterNormoxiaHypoxiaAcclimationLc
Carapace length Lc (mm)2.85±0.37 (17)2.63±0.35 (17)see Fig. 2
Number of embryos14.5±5.0 (17)13.8±5.0 (17)see Fig. 2
Stroke volume Vs (nl)15.3±6.0 (34)12.3±5.0 (34)see Fig. 5
O2 at 18 kPa (nmol h−1 mg−1)268±39 (17)210±45 (17) ***
Hb concentration (μmol l−1)130±29 (17)476±107 (17) *** +
In vitro P50 (kPa)1.09±0.17 (16)0.74±0.18 (16) *** +
Hill coefficient2.10±0.21 (17)1.93±0.15 (17) *
Appendage beating rate fA (min−1)
At normoxia287±65 (34)232±71 (32) **
At Pc,A299±26 (34)318±43 (34) * +
Heart rate fh (min−1)
At normoxia181±30 (34)188±25 (34)+
At PHP346±42 (34)344±29 (34)
At Pc,H379±36 (34)355±26 (34) *** +
Indicators of oxygen tolerance
PHP (kPa)6.1±0.7 (34)6.2±0.8 (34)
Pc,O (kPa)4.3±1.0 (17)2.0±0.6 (17) ***
Pc,N (kPa)2.7±0.5 (32)1.6±0.4 (34) *** +
In vivo P50 (kPa)2.9±0.4 (34)1.9±0.3 (34) ***
Pc,H (kPa)1.4±0.3 (34)1.1±0.3 (34) *** +
Pc,A (kPa)1.6±0.4 (33)0.7±0.3 (34) ***
  • The data show the means ± s.d of all animals of all generations (P, F1 and F2) except for carapace length Lc and number of embryos, for which the data give the means ± s.d of the means of the sampled batches. The numbers of animals and batches, respectively, are indicated in parentheses. The data of the P generation at age 8 days were excluded from the statistical comparison.

    Asterisks indicate significant differences between the two acclimation groups (*P<0.05, **P<0.01, ***P<0.001). A significant (P<0.05) linear relationship between a physiological trait and carapace length (Lc) is marked by a plus sign.