Tens of thousands of travellers were stranded across Greece on Wednesday as seamen and train conductors called a 24-hour strike to protest austerity measures.Ferries were moored at ports across the country, and train services were disrupted as employees protested cutbacks, including the abolition of collective labor contracts that safeguard wage levels and other benefits, AP reported.Dock workers were demanding back pay from ship owners and an end to undocumented and uninsured employees. The workers also want the government to cancel a plan to regulate the minimum number of dock workers required in each crew, saying it would lead to layoffs.Air traffic was also expected to be disrupted on Thursday as air-traffic controllers were to hold a 24-hour walkout.Greek unions have held dozens of strikes over the past three years to protest public sector pay cuts and tax hikes. The heavily indebted government passed the measures to secure bailout loans.