They started in lane six rather than the middle of the field, due to a change in the wind direction, which is done so as not to penalise the fastest crews in qualifying.
Donoghue and Loe had the lead by 1000m and simply eased clear in a terrific performance, winning in 6min 45.08, with the United States 1.49s back in second and Australia third.
The pair had broad smiles as they stood on the dais with flags draped around them.
''We were pretty nervous but we just wanted to go out aggressively and make sure we didn't let anybody get too much of an edge," Loe, daughter of former All Black Richard Loe, in the stroke seat said.
''We're just happy the way it came together."
Harris and Storey, veterans of the elite squad, won their title in thrilling fashion.
They, too, had won both leadup cup regattas but had a real battle with the crews from Poland and Italy.
They were fourth at 500m, third at halfway and got their nose in front at the 1500m mark.
From then it was a cracking tussle with the Poles Zietarski Miroslaw and Meteusz Biskup, the New Zealanders winning in 6:10.070s. 0.59s ahead of Poland with Italians Filippo Mondelli and Luca Rambaldi third 1.26s behind.
''It came to the (final) 500m and we just started sprinting," Harris said.
''Amazing. We've been at it a long time and to finally get it, it hasn't sunk in."
Manson had set the world best time in the Poznan cup regatta and followed that with a second convincing win at Lucerne, but he's been plagued by a niggling side injury in the season.
He was able to get through it at Lucerne but was well off the pace today, finishing fifth more than 12s behind winner Ondrej Synek, which will be a bitter disappointment.
The Czech Republic sculler, who has had a pile of tough duels with two-time Olympic champion Mahe Drysdale in recent years - winning silver behind the New Zealander in Rio last year - triumphed in 6:40.640, holding off Cuban Angel Fournier Rodriguez by almost three seconds, with Britain's Tom Barras third.
The men's eight had taken second earlier in the season at Poznan behind Germany.
They were second behind the same crew today at halfway, but steadily slipped off the pace when the heat went on, finishing last almost 6s behind the winning Germans in 5.34.000, the Germans winning in 5:26.850 with Italy second and the United States third.
But the women's eight, who arrived knowing they were a big chance, can at least reflect on a ripping finale to the championships.
They settled third behind Romania and Britain and had nudged their way to second at halfway. From there it was a rattling battle, the New Zealanders trailing Romania by a mere .022s with 500m to go.
But Canada mounted a fine late surge and just pipped New Zealand for the silver medal by .280s. New Zealand, who had won the Poznan regatta and finished second to Romania in Lucerne, clocked 6:07.270, .690s behind the Romanians, and had made a clear statement that they have become one of the premier eights crews.
''It was tough conditions out there and I guess it just wasn't our day today," stroke Emma Dyke said. ''I thought it was close, that was the hardest we could go."
The Tokyo Olympics in 2020 are clearly in their sights.
''We've got three years to build on that," team mate Lucy Spoors added.
Single sculler Hannah Osborne finished second in the B final.
