The environment below the water in Fiordland is as unique as its acclaimed landscape above. It has a fragile ecosystem and is vulnerable to over-fishing.

In this section

The forty metre band explained in a diagram
The forty metre band of fiord life

The environment below the water in Fiordland is as unique as its acclaimed landscape above.

Runoff from heavy rainfall on the mountains creates a permanent freshwater layer on the surface of the saltwater that varies in depth from 5 cm to over 10 metres.

Tannins, washed out of the vegetation on land, stain the water the colour of weakly brewed tea. This creates a dark layer on the surface that cuts down the amount of light entering the sea water, restricting most of the marine life to the top 40 metres. This band (below the freshwater layer) is calm, clear and relatively warm and is home to sponges, corals and fish of sub-tropical, cool water and deep water varieties.

The fiords support one of the world’s largest populations of black coral trees (about 7 million colonies), with some of them up to 200 years old.

The fiords are also home to brachiopods; clam-like animals that have remained relatively unchanged for over 300 million years.

Although the fiords extend to depths of over 400 metres, life peters out quickly in the gloomy depths. The thin band of life extending around the shores of all 14 fiords is estimated to make up a habitat area of only 42 square kilometres, less than the area of Bluff Harbour on the Southland coast. Because of the small habitat area and the limited opportunity for exchange of material across moraine sills at the entrance to the fiords, these environments are vulnerable to over-fishing.

Bottlenose dolphins (aihe), New Zealand fur seals (kekeno), Fiordland crested penguins (tawaki) and little blue penguins (kororā) are resident in the fiords. Do not stress these animals by approaching them. Let close contact be at their initiation.

The freshwater layer explained.

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