The $5.25 billion expansion of the Panama canal is set to open Sunday at a difficult moment for the international commercial shipping market.

Canal Administrator Jorge Luis Quijano says the shipping market is cyclical, and will rebound.

Quijano said Wednesday the canal expects to benefit in coming years from increased U.S. trade in oil and natural gas.

The drop in world oil prices, the slowdown in China and other factors are affecting traffic and income at the canal.

But the expansion will allow larger ships to pass, increasing efficiency.

The expansion will double the canal's capacity, tap new markets such as liquid natural gas shipments and cut global maritime costs by an estimated $8 billion a year.