Spanish lobster, common on deep rubble reefs in the Hauraki Gulf. (Photo: Crispin Middleton, NIWA)

NIWA undertakes sea floor mapping survey

NEW ZEALAND
Wednesday, August 22, 2012, 00:40 (GMT + 9)

The National Institute of Water and Atmospheric Research’s (NIWA) vessel Tangaroa set sail from Wellington on 21 August to map the seabed in the mid-to-outer Greater Hauraki Gulf.

The Hauraki Gulf, which includes the coast off Coromandel, is one of the country’s most heavily used marine areas. It faces pressure from fishing, aquaculture, marine transport, tourism and sediment run-off from land.

NZ’s Government has recognised this and sought to protect it through the Hauraki Gulf Marine Park Act and its management through the Hauraki Forum.

"The seafloor mapping work will help New Zealand better manage and sustainably develop its ocean resources," said NIWA's project manager Neville Ching.

The mid-to-outer Greater Hauraki Gulf spans 2,100 sqkm, of which about half will be covered within the 22-day survey. Researchers will explore water depths of 40-200 m.

Red mullet (goatfish) sitting on shelly habitat.         (Photo: Crispin Middleton, NIWA)

"We don't know what fish habitats and associated biodiversity are in the mid-to-outer Gulf areas at depths of 40 – 200 m,” said Dr Mark Morrison, who leads NIWA's Coastal Conservation Management project. “That will help us to understand more about what fish do, where they go seasonally and therefore, whether they are at risk from the effects of human activities, such as pollution and sediments."

High-resolution survey lines based on information from retired commercial fishers will be run over special habitat areas and cover deep sponge gardens, tubeworm fields, horse mussel beds, bryozoan ('lace coral') patches and green-lipped mussel and dog cockle beds plus deeper water reefs.

The survey data will supplement information for any future biodiversity assessment and help establish coastal fish-habitat classification.

"We do habit mapping - it's excruciatingly detailed and the positive side of that is people can target things better. The negative side is the fish have less and less chance of hiding," Morrison said, NZ Herald reports.

This research will help government bodies better understand how the Gulf is vulnerable to tsunami impacts. There is some evidence that suggests past tsunami deposits could have reached 14 m above current sea level on Motuihe Island, and the inner Hauraki Gulf.

"The multibeam mapping data collected will significantly help with contributing to the modelling of the risks associated with tsunami events also," said Ching.

This survey voyage is funded by Land Information New Zealand (LINZ) as part of the all-of-government Ocean Survey 20/20 programme that LINZ coordinates to provide NZ with better knowledge of its ocean territory.

By Natalia Real
editorial@fis.com
www.fis.com

Print