The port operator said those market dynamics were expected to continue for the rest of the year, weighing on the annual result.
It also said it expected a temporary hit from the coronavirus outbreak, but that it was too early to predict how much.
"There is normally a slow-down in trade after Christmas and the Chinese New Year, but this is being exacerbated by measures taken globally to slow the spread of the virus. There is a human impact and our thoughts are with those affected. We will continue to closely monitor the situation," Coutts and Gibson said.
Rival Port of Tauranga trimmed its annual earnings guidance last week due to the impact of the virus outbreak, with the logging sector hit the hardest. Auckland differs in that it's primarily an import hub.
Stats NZ today estimated that New Zealand exports to China since the coronavirus outbreak were down about 19 per cent. The data, based on exporter intentions in the period January 27 to February 23, suggested trade with China was about $300m lower than would have been the case without covid-19.
Separately, TIL Logistics also noted the impact of the coronavirus outbreak on the logging sector when it reported a 38 per cent decline in earnings before interest, tax, depreciation, and amortisation of $8.7m in the six months ended December 31, excluding accounting adjustments. That was in line with a profit warning in January.
TIL renegotiated its banking arrangements with ASB Bank, and noted that the covid-19 coronavirus posed a risk to freight volumes if trade was disrupted. However, those disruptions could also support TIL's warehousing revenue if product had to be stored.
State-owned KiwiRail last week said it expected the transport market to remain challenging in the first six months of calendar 2020, as importers, producers, and logistics firms contend with the coronavirus outbreak.