Ulva Island Marine Reserve

Department of Conservation (DOC) scientists spent two weeks off Stewart Island testing the health of Ulva Island/Te Wharawhara Marine Reserve. They launched a new monitoring programme for marine reserves, with help from a partnership with Air New Zealand.

Debbie Freeman, Shane Geange and Vincent Zintzen spent much of their time lying on the seabed observing the anemones, polychaete worms, sea cucumbers and other burrowing animals.

‘Watching what was happening on the seafloor told us a lot about the health of the reserve’, said Debbie. ‘Many divers wouldn’t regard the sediment communities as a high point, but it was busy down there. In some places those sandy communities have been damaged or depleted by dredging or sedimentation or fishing practices, but at Ulva Island they're amazingly diverse.

Debbie Freeman is leading the development of the Ecological Integrity (EI) programme, a new ecosystem-based approach to marine monitoring. ‘In the past DOC surveyed maybe just a few key species within a marine reserve, and not always consistently around the country. The information was useful locally, but couldn’t be used for broader management decisions.

The Ecological Integrity programme takes a much more sophisticated approach at both national and individual reserve level. The data collected will allow us to better manage the coastal marine environment as a whole, not just marine reserves

"There was something mystical about the kelp forests.

A major trip task was to collect tissue samples to build a trophic web of the area - learning who is eating who.

Shane explained, ‘If a snapper eats a crab, the amount of nitrogen stable isotope in its body will tend to accumulate and will be higher than that of the crab. This information tracks the web of trophic interactions, giving us quite a nuanced idea of how the reserve is developing and changing.’

The team took over 25 hours of footage of the seafloor, which will be used to draw a habitat map of the reserve. They used drop cameras, sometimes pulled on sleds, for this work. They also spent hours diving in the majestic macrocystis (kelp) forests, photographed here by Vincent Zintzen.

‘There was something mystical about them, the way the light falls’, said Vincent. ‘The seaweeds of Ulva Island and the Stewart Island area are some of the most diverse in the country. It’s particularly well known for its reds, and we did see big beds of red algae with communities of little fishes and invertebrates. They’re spectacular and interesting to study.’

The octopuses were so bold and curious that they proved a problem during the camera work, said Debbie. On several occasions they attached to the camera and we had to pull it up to detach the octopus. We’ve footage of an octopus wrestling a carpet shark which was pretty special.’

The waters around Stewart Island are popular with potentially more dangerous sharks too, namely white pointers, bronze whalers and seven gills. While the team did spot a white pointer in their video footage – ‘cruising past the drop camera’ – Shane said they didn’t encounter any on their dives.

‘We followed strict protocols – diving and ascending from shore (avoiding mid-water ascents), having a lookout, and not hanging around on the surface.’

The EI programme is not just looking at the marine environment, it’s examining interactions across land and sea. For example, at Ulva Island the team counted shag numbers in Paterson Inlet.

‘New Zealand used to be covered in seabirds and they must’ve been important providers of nutrients to terrestrial species’, said Debbie. ‘Ulva Island is a wildlife sanctuary surrounded by a marine reserve, surrounded by a mataitai, so it’s the perfect place to study that land-sea connection.’

After two weeks of perfect weather and intense diving, the team brought their samples back to Wellington for the painstaking job of examining the data. This will take up to a year but, once finished, DOC will have a good idea of the health and functioning of the marine reserve’s ecosystems. They’ll be able to compare it with similar places in New Zealand that are not reserves, building a picture of the health of valuable species and other more intangible assets. Over the next 10 years, the information gathered by the Ecological Integrity programme will enable more sustainable management of our wonderful coastal waters.  

There are 37 marine reserves around New Zealand. The Department of Conservation welcomes diving in marine reserves – please remember to take only photos, leave only bubbles, and take care when anchoring.

Updated number of marine reserves in New Zealand

As of August 2020, there were 44 marine reserves around New Zealand. The Department of Conservation welcomes diving in marine reserves – please remember to take only photos, leave only bubbles, and take care when anchoring.