Marlborough Sounds’ Multi-beam Data Helps Inform NZ’s Best-ever Predictive Habitat Maps

NIWA scientists have generated the most detailed predictive habitat maps for any coastal area in New Zealand, with the help of Council-funded multi-beam mapping data.

The researchers, led by NIWA scientist Dr Tara Anderson, recently presented the findings of their research to the Marlborough District Council. These findings confirm the Council’s significant investment in seabed mapping of the Marlborough Sounds has been a valuable investment, said Council coastal scientist Oliver Wade.

“The data this mapping produces has long been heralded as a huge step forward in the effective management of the Marlborough Sounds’ unique coastal ecosystem and now we are starting to see some really tangible results. It has helped to provide important new habitat insights for Queen Charlotte Sound/Tōtaranui and Tory Channel/Kura Te Au - the results from this project have exceeded all expectations,” he said.

The multi-beam mapping project has covered all of Queen Charlotte Sound/Tōtaranui and Tory Channel/Kura Te Au and was conducted in partnership with Land Information New Zealand (LINZ) and the National Institute of Water and Atmosphere (NIWA) in 2016/2017. Since then the project has been extended to include Pelorus Sound/Te Hoiere, Admiralty Bay and Te Aumiti/French Pass.

NIWA’s research project, funded by the Council, modelled the distribution of two nationally important ‘living’ habitats - Galeolaria hystrix and frame-building bryozoans. “Both these species can form extensive reef-like habitats, in a similar way to those created by corals in tropical waters,” said Oliver.

“These habitats support high marine biodiversity, but like corals are fragile and susceptible to damage from bottom contact fishing methods and anchoring,” he said.

Galeolaria live in a hard calcareous tube and filter plankton from the seawater. These tubeworms are unusual in that they settle on top of other Galeolaria tubes, and can over many decades form metre tall mounds that extend kilometres over the seafloor.

Bryozoans also filter plankton, but only some species are able to form reef-like colonies like those seen in the Sounds, but these can take decades to form.

Dr Anderson described the combination of the multi-beam mapping and previously gathered 'Life on the Seabed’ video data funded by NIWA used to model these habitats as “one of the best data sets in the country” and confirmed its value in being able to work out what areas within Queen Charlotte Sound/Tōtaranui are important for these marine species.

“Multi-beam mapping tells us about the physical structure of the seafloor. Video tells us about the animals and plants living on the seabed. “The video data from the 'Life on the Seabed’ survey in 2020 collected 6,251 data points from 358 sites throughout the eastern Sounds”. Both of those surveys were ground-breaking for NZ in providing very high-resolution datasets.

“This recent study brings those two amazing datasets together to create a really detailed map of where we predict these two habitat-forming species to occur - and their abundance - across the whole map. NIWA is the first to provide this combination of data-rich biology across such high-resolution multi-beam maps for such a large coastal region in New Zealand,” she said.

From the ‘Life on the Seabed’ study, Dr Anderson said it was possible to identify where Galeolaria grow, what features of the seafloor are important, including what depths they occur in, what hard structure they attach to and a suite of other characteristics.

“Overlaying this new biological information on the multi-beam map data, means we can now predict suitable areas for this species across the entire survey area,” she said. “We can also do this for bryozoan patch reefs, which are also known to be important nursery habitats for juvenile blue cod.

“This information is critical to New Zealand’s coastal managers, and these new maps are already providing a significant new tool to aid in the management and conservation of these important habitats, and the diverse communities that they support,” she said.

Over the coming months this research will provide the foundation maps and knowledge for selecting and revising areas for the Council’s Ecologically Significant Marine Sites planning.

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