Kelp on shore platform, Curio Bay, Southland

Bull kelp (Durvillaea antarctica) is one of New Zealand’s largest species of seaweed, with thick, rubbery fronds reaching up to 10 metres in length. It is common on the more exposed coasts throughout the country, thriving where many other types of seaweed would suffer great damage or be washed away by heavy swells. The Southland coast is a particularly boisterous environment that is directly exposed to the huge waves churned up by subantarctic storms over the Southern Ocean — a perfect habitat for bull kelp.

Bull kelp has several adaptations which allow it to survive and prosper in such hostile conditions. Its fronds are naturally buoyant which helps them to float towards the surface for maximum light, even in turbulent water. The fronds and stems are also tough and extremely flexible to weather the relentless pounding of storm waves, and the entire plant is literally welded to the bedrock by an extremely strong holdfast which can withstand almost any storm that may pound the coast.

The holdfast of bull kelp can in fact be stronger than the rock it is attached to, so that during particularly severe storms a whole plant may be ripped away from the sea floor, complete with a piece of rock still firmly attached to its holdfast.