Ocean between NZ and Australia a climate change "hotspot"

By Jamie Morton

Photo / iStock
Photo / iStock

The ocean between New Zealand and Australia is one of the fastest-warming ocean regions on the planet, heating up at four times the global average.

Now scientists are working to understand what this accelerated warming in what's called the East Australia Current means for the coastal environments of both countries and their resident marine species.

Oceanographer Moninya Roughan, a visiting Seelye Fellow at the University of Auckland, is researching the effect of one of the strongest influences on ocean conditions in the region, and will be giving a public talk on her work this week.

"New Zealand and Australia sit at the tail pipe of the East Australia Current where global ocean circulation affects the coastlines of both countries so we need a much better understanding of its effects," she said.

Roughan, from UNSW Australia, leads a comprehensive ocean observation system comprising a network of moorings, HF Radar and an underwater autonomous "glider" that transmits data in almost real time by satellite.

The data should help scientists better understand what drives change in this part of the ocean.

Measurements over the past 70 years show that over the past century, surface temperatures off the coast of Tasmania have risen as much as 2.28C.

One of the key species that may be affected by environmental changes are tiny lobster larvae that spend a year adrift at sea before returning to the coast to develop into juveniles.

With many not making it back from the journey, the lucrative spiny lobster fishery is facing decline and scientists suspect it is due to changing ocean conditions.

The lobster project, a collaboration between UNSW, Associate Professor Andrew Jeffs from the University of Auckland's Institute of Marine Science and NSW Fisheries, involves observing lobster larvae swimming in a special tank with a continuous flow of seawater to mimic natural conditions.

So far the research has established that while ocean warming may favour baby lobster and help them develop, the strengthening currents transport them further south than normal.

Roughan's lecture will be held at 6pm in the Medium Chemistry Lecture Theatre, Building 303, 23 Symonds St, Auckland.

- NZ Herald

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