Maritime operations along the lower Mississippi River began slowing down Friday morning as the industry prepares for Tropical Storm Karen.

The Associated Branch Pilots, state-commissioned river pilots who guide foreign ships through the mouth of the Mississippi River, discontinued service at 6 a.m., the Port of New Orleans said.

The river remains open, a spokesman for the Coast Guard’s 8th District said. The Coast Guard has not determined when it will close the river to traffic.

Only one cargo ship was scheduled to arrive at the Port of New Orleans today but it has been delayed. Nine cargo vessels that had been scheduled to leave port this weekend will remain until the storm passes.

Two cruise ships that had been expected to arrive at the port on Saturday and Sunday will be delayed until Monday because of the storm.

The Carnival Elation, which was scheduled to arrive in New Orleans on Saturday after a five-day cruise to Mexico, will remain at sea until the Coast Guard gives clearance for it to return, Carnival said Friday.

As a result, the Elation’s next trip has been cut from a five-day Mexican cruise to three days at sea. Guests who take the truncated trip will receive a 50 percent discount and half off another five-day, Carnival cruise.

The Carnival Conquest, which is operating a seven-day cruise to the Caribbean and Bahamas, also will remain at sea until the storm passes.

The Conquest’s next trip will be shortened from seven days to six days and will include one less port call. Guests who agree to take the modified cruise will receive a one-day, pro-rated refund, Carnival said.