Development of embryos of Hormosira banksii from three source regions (southwest Victoria, eastern Victoria/southern NSW, and Port Phillip Bay, pooling three sites in each region) after 7 days of culture at 15, 18, and 21°C showing a) mean (±SE) percentage of embryos with greater than four cell divisions and well‐developed rhizoids, and (b) mean (±SE) rhizoid length. Broken horizontal lines above bars in (b) indicate significant differences among temperature treatments based on Tukey's test after the full ANOVA model, whereas letters on bars in (a) indicate Tukey's test results among treatments for each region individually after simple main effects analysis (because of significant temperature × region interaction in the full model)