Fig 1.
Schematic of design of experiment to determine the effects of ocean acidification on snow crab embryos and larvae. Arrow indicates that the same females were held over the full 2-year experiment and were mated between years. Larval treatments were fully crossed (9 total combinations) but only one treatment expansion is shown for sake of space.
Table 1.
Water physical and chemical parameters in female experimental tanks.
Fig 2.
Effect of pH on snow crab embryo stage.
Effects of three different pH treatments on the stage of embryo development in snow crabs over two successive brooding cycles (Year 1 and Year 2). Symbols are the mean stage for each month and error bars are one standard deviation. All embryos were sampled on the same day; however, treatments are offset for clarities sake.
Fig 3.
Effect of pH on snow crab embryo morphometrics.
Non-metric multidimensional scaling plots of snow crab embryo morphometrics measured monthly during two brooding cycles (years) and reared in 3 different pH treatments. Plots on the left represent the year 1 embryos (first brooding cycle), and those on the right represent year 2 embryos. Top row of plots graph the data by month to show embryo development and the bottom 2 rows graph the data by pH treatment.
Fig 4.
Effect of pH on snow crab fecundity.
Fecundity, defined as the number of viable larvae hatched, in females held in 3 different pH treatments over 2 years. There are no statistically significant differences among treatments in either year. Error bars are plus 1 standard error.
Fig 5.
Effect of pH on snow crab hatching success.
Hatching success in female snow crabs held in three different pH treatments for 2 years. Values represent the mean in each category. There are no statistically significant differences among treatments in either year.
Fig 6.
Effect of pH on snow crab carapace mineral content.
Calcium and magnesium content and Mg:Ca ratio in the carapaces of female snow crabs held for 2 years in 3 different pH treatments. Error bars are 1 standard deviation. There are no statistically significant differences among treatments.
Table 2.
ANOVA result for effects of water pH on snow crab embryos and females.
Table 3.
Water physical and chemical parameters in two years of larval experiments.
Fig 7.
Effect of pH on larval snow crab starvation-survival.
Cumulative percent mortality of snow crab larvae in starvation survival experiments in two years of experiments. Treatments represent the pH treatments during the embryo and larval portions of the experiments: A-Ambient pH, 7.8-pH 7.8, 7.5-pH 7.5. Points represent the average of five replicate trials and lines show the best fit curves (see Table 2 for parameter estimates).
Table 4.
Ranking of snow crab larvae starvation survival models.
Table 5.
Snow crab larval starvation survival model parameters.
Fig 8.
Water pH and snow crab larval mass.
Effects of holding pH during the embryo and larval stages on the dry mass of snow crab larvae. Bars are means + 1 standard deviation. For larval treatments, “At hatching” represents larvae sampled immediately after hatching and Ambient, pH 7.8, and pH 7.5 represent larvae held at those pH treatments for 7 days. Statistically significant differences (Tukey’s test) among treatments are indicated with different letters.
Fig 9.
Water pH and snow crab larval elemental composition.
Effects of holding pH during the embryo and larval stages on the carbon and nitrogen contents and the C:N ratio of snow crab larvae. Bars are means + 1 standard deviation. For larval treatments, “At hatching” represents larvae sampled immediately after hatching and Ambient, pH 7.8, and pH 7.5 represent larvae held at those pH treatments for 7 days. Statistically significant differences (Tukey’s test) among treatments are indicated with different letters.
Fig 10.
Water pH and snow crab larval calcium and magnesium content.
Effects of holding pH during the embryo and larval stages on the calcium and magnesium contents of snow crab larvae. Bars are means + 1 standard deviation. For larval treatments, “At hatching” represents larvae sampled immediately after hatching and Ambient, pH 7.8, and pH 7.5 represent larvae held at those pH treatments for 7 days. Statistically significant differences (Tukey’s test) among treatments are indicated with different letters.
Table 6.
Summary ANOVA results for snow crab larval experiments.
Fig 11.
Effect of water pH on snow crab larvae morphometrics.
Non-metric multidimensional scaling plots of morphometrics of snow crab larvae hatched from larvae held in three different pH waters in the first and second years of the experiment.
Table 7.
SIMPER analysis results for effect of water pH on snow crab larval morphometry.