New controls on imports entering Britain from the Republic of Ireland have come into effect.
The changes, which are a result of Brexit, require firms to pre-lodge customs declarations ahead of shipping products across the Irish Sea.
Agri-food exports also have to be pre-notified to the UK authorities and in some cases they have to be accompanied by an Export Health Certificate.
The additional requirements come on top of formalities already in place for goods that are being exported to the EU.
Loads which have not had the required documentation properly completed and filed at least 24 hours in advance will not be allowed to board ferries leaving Ireland for the UK.
But while authorities had been concerned about the preparedness of smaller Irish businesses for the changes, major disruption at ports is not anticipated.
This evening a spokesperson for the Department of Transport said Dublin Port and Rosslare Europort continued to operate efficiently this morning.
"Overall, there is a high-level of awareness and preparedness among hauliers of the new UK import rules and compliance with same," the spokesperson said.
"These are significant changes by the UK. They will require businesses, particularly those in the agri-food sector, to examine their supply chain and to, in many cases, make changes to adapt their business processes."
"The Department will continue to engage with the shipping and haulage sector and monitor any impacts arising from these new UK import rules at the ports."
Physical checks of goods entering Britain from Ireland will not be introduced until later in the year.
Explainer: The new controls on Irish exports to the UK
The controls were supposed to be put in place a number of times over recent years, but were repeatedly delayed because UK agencies were not ready.
Campaigns have been run by Irish and British government agencies to bring Irish exporters, logistics providers, ferry operators and others up to speed since the plans to commence the controls were announced last August.
The requirements do not apply to goods that are moving from Ireland to Northern Ireland, while qualifying goods originating in Northern Ireland will continue to have unfettered access to Britain.
The rules do apply though both to goods transported directly from Ireland to Britain or indirectly via Northern Ireland to Britain.
