New Zealand’s fiords, in the south-west of the South Island, are unique. They are spectacular to look at – and they are host to a dazzling variety of animal life. Their waters are so dark that creatures which usually live only in the deep ocean can survive there, giving scientists a peephole into little-explored territory.
Full story by Paddy Ryan
Main image: Bowen Falls, Milford Sound
The Short Story
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What is a fiord?
A fiord is a long, narrow inlet of sea, with steep sides gouged out by a glacier.
How the fiords were made
New Zealand’s 14 fiords are in the south-west of the South Island. They were carved out of the mountains about 20,000 years ago by glaciers. When the ice melted, the sea came in and filled the fiords. Mounds of rock block the entrances, so that there is little flow of water between the sea and the fiords.
A unique environment
A layer of fresh water lies over the salt water. It is created when heavy rain runs into the fiords. As the water runs down banks, it becomes brown-coloured. The brown layer of fresh water reduces the amount of sunlight filtering through. The waters are dark and many creatures which usually only survive in very deep, black water can also live in the fiords.
Most creatures in the fiords live on the underwater rock walls. The top layer of fresh water is home to only a few hardy creatures such as mussels, shrimps and barnacles. Just below this layer, the rock walls are covered in huge numbers of sponges, corals, sea stars, sea urchins, lace corals and sea squirts.
Further down, sea cucumbers and glass sponges make their homes.
Not much lives in the dark basins more than 40 metres deep. Heart urchins, tube worms and crabs are among the animals that live on the muddy floors of the fiords.
Fish and marine mammals
Over 150 types of fish live in the fiords. The blue cod and butterfly perch are so tame that they swim up to divers.
Fur seals venture into the fiords to live, and a group of bottlenose dolphins has made a permanent home there.
Fishing and tourism threaten life in the fiords. A group called the Guardians of Fiordland Fisheries and Marine Environment was formed in 1995 to make sure that the area is not harmed. The government established a large marine management area in Fiordland in 2005.