Handwritten files provide sediment treasure chest

Handwritten files provide sediment treasure chest

A NIWA scientist who spent years poring over handwritten scientific notes stored in about 50 large wooden drawers, has seen the fruits of her labour now being used in ways she never imagined.

Marine geologist Dr Helen Bostock has created a new seabed sediment database for New Zealand’s Exclusive Economic Zone (EEZ) and extended continental shelf. The database, called nzSEABED, provides information on the percentage of mud, sand and gravel contained in seafloor sediment, which she has used to produce charts plotting their distribution.

A carbonate percentage is also included, which reveals how much of the sediment is produced by marine creatures to create their shells, versus the amount of sediment washing off land.

The results have just been published in two papers in the New Zealand Journal of Geology and Geophysics, one focussing on the EEZ and the other on the coastal regions.

Dr Bostock first started work on the database 10 years ago when she was looking for information for a project that required her to look up archived paper files dating back to the 1970s and then digitise them.

“I thought that this was crazy and that we should have a digitised database where this information can be readily accessed.”

She also realised that an easy-to-access database could have a range of applications for scientists and others working in related fields, so set about creating it.

In the wooden drawers stored at NIWA’s Wellington site were folder after folder of information about historic sediment samples collected and analysed by researchers, some dating as far back as 1950 when depth was recorded in fathoms and there was no GPS to pinpoint latitude and longitude.

Dr Bostock first needed to interpret the handwritten information and then key it in by hand to the database. That took three years and ended up comprising approximately 10,000 data points.

“It’s been an interesting historical exercise seeing how things used to done, the methods used and the detailed work done on some of the samples. I really hope people take the dataset and use it as opposed to having it in a paper archive that is rarely used.”

Much of the information was originally collected in the 1960s and 70s when the New Zealand Oceanographic Institute was making a concerted effort to collect seabed samples around New Zealand.

From 1970 to the 1990s a series of New Zealand coastal charts were produced by researchers working on specific areas of commercial or scientific interest. But coastal charts of some regions were not completed, so the idea of this project was to produce a seamless map of the sediments of the EEZ.

With the help of an overseas collaborator, 20,000 data points were then added from international databases held at overseas research institutes that helped fill in gaps, particularly in offshore areas. That data also included information from the Challenger expedition from 1872-76, a scientific voyage of discovery that laid the foundation for modern oceanography.

However, it is how the database is being used now that most excites Dr Bostock. “It is already being used for more things than I had ever imagined.”

So far NIWA scientists have used it as a base layer to predict the habitat of marine species that live on the seabed – working out the types of sediment different species prefer and mapping where they may be located.

Other researchers are using it for “sound modelling” for Maui dolphins as they seek to better understand the soundscapes of dolphin habitats, which will vary in regions of soft and hard seabeds.

For scientists interested in the sediment itself, the database will aid understanding about dispersal and variability in sediments around New Zealand.

“I don’t think of this as an end point – it’s more of a starting point for a range of new research. We have established a baseline and with that information we can go out and make comparisons about how the seafloor changes and work out why, whether that is a result of land use changes or climate change."

The published paper has been deliberately targeted at an audience wider than the scientific community as Dr Bostock believes the database will be useful for people working in adjacent fields, including marine infrastructure such as installing marine cables, and regional councils who need better information about the seafloor.

“I hope it will be used by a wide variety of people who would never have previously had access to this information.”

The dataset can be accessed here: https://nzodn.nz

Sn image of what makes up the seafloor around Wellington and the north of the South Island. credit NIWA.

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