Waikato oceanographer says Rena oil best washed up on beaches

A University of Waikato oceanographer says the Bay of Plenty has dodged a bullet with oil from stricken ship Rena washing up in the best possible places.

Beaches Less Damage

Dr Willem de Lange from the Waikato University Coastal Marine Group says oil from Rena is far better being washed up on the beaches and rocky coastline, than in areas where it will do permanent damage such as estuaries.

Dr de Lange has been studying the effect of winds and currents on the dispersal of 350 tonnes of oil that leaked from the ship after it crashed into Astrolabe reef in early October.

“With Tauranga, so much oil in such a small place tends to overwhelm the natural ecosystem for a while, but the ecosystem is equipped to handle this.

“Oil floats on top of the water so it affects the upper parts of the tidal reaches, so high up on the beaches, on rocks and into estuaries.”

Oil from Rena first began to hit Bay of Plenty beaches on October 10, and while the main beach is open beaches continue to be monitored and could be closed again at short notice if fresh oil is found. Clean up is continuing on the worst affected beaches.

“Sometimes the best thing to do with oil spills is leave them alone,” says Dr de Lange. Where the oil goes depends on the wind, waves, tides and the current. With rocky coastline and beaches, given time the oil will be eaten by bacteria.”

Estuaries Safe

Thankfully oil from Rena has so far had a relatively low impact on the environment and is yet to be found in any estuaries in large quantities, says Dr de Lange.

“The problem is when oil settles in estuaries. Estuaries are very difficult to clean and don’t have an environment that aids biodegradation. When oil gets into the vegetation in estuaries it’s almost impossible to clean and any attempt to do so destroys the environment and the wildlife.”

Unlike on beaches and on rocky coastline, where oil will be exposed to microbes in seawater and sunlight – both key in biodegradation – estuaries do not have an environment conducive to biodegradation and will be heavily affected by any oil that reaches them, says Dr de Lange.

“The Rena spill has been highly visible and highly emotive, but it’s not going to have a huge environmental impact. Oil spills are not uncommon but it’s not often they happen on prime coastline."

Work completed by Coastal Marine Group and other Waikato University staff in the days following the Rena grounding will provide a platform to monitor recovery. The University of Waikato Coastal Marine Group has more than 30 years’ experience in state-of-the-art sampling, measurement and monitoring of shallow water environments.