How much more remote can you get than the Rangitāhua Islands?

1,000 meters to be precise. That's how deep some of the science equipment plunged as part of last year’s Te Mana o Rangitāhua expedition. Researchers Joe O’Callaghan, Sarah Searson and Arnaud Valcarcel used Conductivity, Temperature, and Depth (CTD) monitors to understand the raw components of seas surrounding Rangitāhua.

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

Measuring conductivity is an indirect way of understanding the salinity of water. It works on the principle that the presence of ions and salts increase water’s ability to carry an electrical charge. Hence more salt equals a greater conductor. 

Suggestions of hot thermal vents or deep sea craters can indicate thriving ecosystems, but require complex, delicate oceanographic equipment that cannot be sent down to unknown depths. The CTD equipment monitors depth without having to reach the bottom of the sea floor, allowing future exploration to be safe. 

Arnaud Valcarcel (Right) with Tangaroa crew monitoring oceanographic equipment.

For our oceanographers, temperature is more than degrees celsius. Deep water currents have different temperatures to above water and can indicate the water’s origin. Also, patterns of water fluctuating up and down within the water column (called Vertical Waves) can also be indicated with temperature. Vertical waves are important for opportunistic organisms like microbes and fish larvae. Meaning a flow on effect of ocean physics, is its impact on ecosystems.  

Under the Te Mana o Rangitāhua project, all aspects of the environment are studied holistically. Baseline environmental conditions will be connected to ecosystem taonga and assist long term monitoring of the region. The Ngāti Kuri iwi who care for Rangitāhua are utilising cultural and scientific knowledge to understand the mysteries of this remote location. 

Image right: Sarah Searson with CTD monitor

Rangitāhua expedition

Explore the full series of blogs from the Rangitāhua voyage.