Fig. 3. Breaking strain for threads over time of exposure in four seasons. Symbols represent means ± s.e.m. values (N=11–29). Tests were performed in a 15°C seawater bath at an extension rate of 10 mm min^–1. Note that no testable threads persisted beyond four weeks during the summer; the value for six weeks exposure was conservatively estimated from the four-week values (broken line).