New Zealand’s National Institute of Water and Atmosphere (NIWA) will launch at $3.7 million study to assess the potential impacts of deep-sea mining.

The New Zealand Herald reported that the study, led by Malcolm Clark of NIWA will focus largely on the impact of sediment plumes that would be created by a disturbance to the seafloor by mining operations.

The government of New Zealand has stated a strategic priority to reap benefits from seabed resources, the sustainability and integrity of the natural environment also had be maintained, he said.

What we know about the structure of deep-sea communities remained limited, Clark said; it's estimated that only 20 to 30 per cent of the seafloor species have been formally described.

"Of particular importance, however, is a lack of knowledge of the key species or communities that drive ecosystem function, and when human activities could tip a system from the one we know to something different."

Global estimates of the number of known marine species total 250,000 - but scientists believe this figure is only about one quarter of what is believed to really be out there.

The study will test the belief that life is highly sensitive to sedimentation stirred by seabed disturbance, and investigate specific impacts, any differences in resilience and prospects for recovery.

Clark said general effects could be expected from seabed mining, ranging from physical damage to the seafloor as it was mined, to those that could affect a wider area, through sediment plumes that could bury animals, or eco-toxic releases that could contaminate environments are already known.

Yet, because deep-sea mining had not yet taken place anywhere in the world, the actual effects were uncertain.

Most studies to date had focused on the direct impact of disturbance, and there had been little work looking at the effects of sedimentation from deep-sea mining.

Work that had been carried out in shallow water couldn't be applied to what might be expected in deep-sea habitats, where effects would vary between sites and depths.

But Clark said it could still be assessed how ecosystems responded to decreased light levels, how their feeding or respiration was affected and whether such effects were lethal or could be tolerated for certain periods of time.

The Niwa-led study would combine in-situ observations on the effects of sediment deposition with lab-based experiments.
Areas of the seabed would be disturbed, then closely monitored by ship-based surveys, with sampling to be repeated over time to determine which seafloor communities were more affected than others, and whether species and communities could eventually recover.

The churned-up sediment itself would also be assessed to refine plume models that predict spread, while back in labs, experiments would use live deep-sea coral and sponge species to assess their resilience.

Ultimately, the research would define the levels at which sediment impacts became ecologically damaging and offer insights into how such impacts might be reduced.