Many things in our ocean can be called ‘sea-weeds’, but very rarely are they noxious or undesirable. In fact the abundance of seaweeds provides crucial habitat for many animals. Young turtles, fish, crabs, sharks and more, use seaweed environments as nurseries, while species of seahorses, fish, and shrimp will always call seaweeds home.  

Blog by Lauren Timms, Assistant Collection Manager, Te Mana o Rangitāhua 

Scientific Diver Ella Lis with macroalgae sample.

Late last year scientists and Mana Whenua traveled to one of the few pristine environments left in the world; Rangitāhua. This area of the world is not only remote but nutrient poor, making it a perfect place for unusual seaweeds. Of the 154 species recorded at Rangitāhua, 83 are found nowhere else in New Zealand.  

But what is seaweed and what do we know about it? Scientists call most seaweeds macroalgae because they are multicellular-algae. This group are powerhouses of photosynthesizing, and could play a critical role in capturing CO2 to mitigate climate change. Macroalgae contains mixed groups of green, brown, or red, so can be visually very different. Being at the bottom of the food chain, they are a ready food source for many animals, and even humans. 

Macroalgae Liagora sp

Accompanying us on the Rangitāhua voyage was NIWA scientist Roberta D’Archino. A leading researcher in New Zealand’s macroalgae, Roberta was excited to see undescribed species and reproductively active individuals not seen before. Amongst Rangitāhua’s macroalgae we observed fish larvae, crabs, worms, sea stars, urchins and more. Together these small scale organisms and the seaweeds they live on, provide a foundation for the surrounding ecosystems of Rangitāhua.  

By identifying organisms in the environment and understanding the roles they play, we will monitor the health of Rangitāhua over time, and help it remain a pristine environment. The sustainable and local management of this ecosystem will ensure its longevity into the future. 

Macroalgae Delisea pulchra

Rangitāhua expedition

Explore the full series of blogs from the Rangitāhua voyage.