Table 1.
Effects of temperature and pH on reproductive traits in echinoderms.
Fig 1.
Sand dollar embryos 3 hours post-fertilization.
(A). fertilized and unfertilized embryos at 50× magnification. (B). Close up at 112× magnification highlighting fertilization membrane. Z-stack images were captured using an Axio Zoom V16 stereo microscope equipped with an Axiocam 506 color camera (Zeiss, Germany).
Fig 2.
Effect of water temperature on reproductive traits of sand dollars, Dendraster excentricus.
(A). fertilization rates, (B). sperm curvilinear velocity, and (C). proportion of sperm that were motile. Data for the three traits were fitted with non-linear functions (quadratic, modified gaussian and gaussian respectively) and plotted with 95% confidence intervals (shaded areas) determined by residual bootstrapping [102].
Fig 3.
Effect of water temperature on reproductive traits of red urchins, Mesocentrotus franciscanus.
(A). fertilization rates (B). sperm swimming velocity, and (C). proportion of sperm that are motile. Data were fitted with non-linear functions (modified gaussian for fertilization, quadratic for sperm velocity and motility) and plotted with 95% confidence intervals (shaded areas) determined by residual bootstrapping [102].
Fig 4.
Estimates for derived parameters from thermal performance curves of sand dollar and sea urchin reproductive traits.
Reproductive parameters include rmax = maximum rate, Topt = thermal optimum, and Breadth = thermal breadth in panels A-C respectively. Error bars represent the 95% bootstrap confidence intervals.
Fig 5.
Combined effects of temperature and pH on reproductive traits of sand dollars, Dendraster excentricus.
(A). fertilization rate, (B). sperm curvilinear velocity and, (C). sperm motility. N = 3 adult pairs. Error bars represent 1 SE.
Fig 6.
Comparison of empirical and modelled fertilization rates in single factor experiments.
Fertilization responses to sperm swimming velocity (panels A, D), motility (panels B, E) and water temperatures (panels C, F). Top row are for sand dollars and bottom row are for sea urchins. Lines represent estimates from fertilization kinetics model [97, 109] parameterized with swimming velocities and symbols represent empirical fertilization rates from this study.
Fig 7.
Comparison of empirically measured versus modelled sand dollar fertilization rates.
Fertilization responses to: (A). sperm swimming velocity; (B). sperm motility; (C). water temperature and; (D) pH. Lines represent estimates from fertilization kinetics model parameterized with swimming velocities and symbols represent empirical fertilization rates from this study [97, 109].