There will no nodule mining in the Cook Islands until there has been a public Environmental Impact Assessment (EIA). In this article Gerald McCormack of the Cook Islands Natural Heritage Trust discuss some topics that need to be researched, and estimate the total time it could take to obtain enough information to implement a robust EIA to decide if nodule mining impacts would be acceptable or not.

Seabed mining is being promoted as a possible major revenue stream to complement tourism and the Tuna fishery. With major revenue streams it is not a matter of no environmental impacts; it is a matter of acceptable levels of impacts in relation to the benefits. For example, for tourism revenue there is a general acceptance of the significant contribution to climate change of long‑haul flights and significant local impacts, such as a greater demand on freshwater resources and a significant increase in landfill waste.

For seabed mining we need scientific research on the numerous possible impacts so we can all discuss the likelihood of each impact occurring, and, more importantly, how large or significant the impact is likely to be.

I will discuss three common concerns about nodule mining, and then analyse an actual research expedition to the Clarion Clipperton Zone (CCZ) to estimate the likely duration of research required on the biodiversity and environment in the nodule-rich Central Area of the South Penrhyn Basin (SPB).

To complement this biological knowledge, I will comment on the likely time to obtain sufficient information on proposed mining technology and processes to implement a robust EIA on the acceptability of impacts.

Ocean acidification

It is well known that the deep sea (below 500m) stores (sequesters) most of the carbon dioxide produced by human activity. Almost all of it is stored within the water as dissolved inorganic carbon (carbonate and bicarbonate ions) which is slightly acidic. As the concentration increases the ocean become increasingly acidic or acidified.

The idea that nodule mining could increase ocean acidity concerns the carbon stored (sequestered) on the seabed as (1) solid inorganic carbon in the form of calcium carbonate (limestone), and (2) solid organic carbon in the form of animal and plant remains that have sunk down from the surface waters. The sinking of organic matter is called “marine snow” or, technically, POC Flux (Particulate Organic Carbon Flux).

The release of acidic soluble carbon from sedimentary limestone is a non‑issue locally because limestone is absent from the sediments at the depth of SPB nodules. The remaining concern is that seabed organic carbon will be mobilised in the sediment plume which will increase its decomposition by bacteria to release acidic soluble carbon into the water.

However, Orcutt et al. (2020) concluded that the mobilisation of seabed organic carbon by nodule mining “will have a trivial impact on the ecosystem service of carbon sequestration” for two reasons: (1) “these sediments contain extremely low quantities of organic matter (< 0.5%)”; and (2) the organic matter is “likely to be highly processed” making it not particularly available for bacterial decomposition and therefore most of it will resettle on the seabed.

Although Orcutt’s report of expert bacteriological opinion concluded that the release of seabed organic carbon will probably be insignificant, we should undertake research to measure the actual level of this impact.

Loss of vital medicines

Medicines have been developed from chemicals found in a very wide variety of bacteria, fungi, plants, seaweeds and animals. Many have also been found in deepsea animals, especially in extreme environments, such as around hydrothermal vents in areas of seafloor volcanism. Although we have no hydrothermal vents in the Cook Islands EEZ, it is still possible that some important medicines could be found in our seabed animals and bacteria.

Although it is often claimed that nodule mining could lead to the loss of vital biochemicals in our seabed biodiversity, there is actually no reason for any such loss. All animals and bacteria recovered during exploratory research should be made available for medicinal assessment.

In this way, instead of waiting for a developed country to fund this important seabed research, we can reap the benefits early by making it part of the baseline biological surveys under the Exploratory Licences.

Major loss of megafauna

Vanreusel et al. (2016) quantified the nodule-associated sessile and slow-moving megafauna in the CCZ; and her paper is commonly used to show nodule mining will cause a major loss of associated megafauna.

The Japanese 2000 expedition (Okamoto, 2003) did a comparable megafauna video-survey in the Central SPB that showed a very low level of nodule-associated attached and slow-moving megafauna.

The graph of megafauna in nodule-rich areas shows that central CCZ samples from the French (IFR), Belgian (GSR) and Ocean Metals (IOM) concessions had around 30 individuals/100m² using ~1km video transects. In very sharp contrast, the Japanese data from a single 20km transect in the Central SPB recorded a mere 0.2 individuals/100m². See Figure 1.

Further research is needed to verify the Japanese conclusion in different parts of the Central SPB using short ~1km video-transects. As it stands, nodule mining in the Central SPB will destroy less than 1% of the nodule-associated megafauna that would be destroyed by equivalent mining in the Belgian GSR area of the CCZ.

Biological research duration

Cook Islands nodules were researched during 15 expeditions from 1974 to 2000, mainly by the Japanese RV Hakurei-Maru 2. The research was funded by developed countries, mainly through SPC/SOPAC, and it focused on assessing the distribution, abundance and composition of nodules as a future revenue resource for the Cook Islands. It was not until the 2000 expedition that Hakurei-Maru 2 undertook some preliminary biological research.

We now need much more biological research to assess the likely level of impacts of proposed mining systems to decide if this industry is acceptable or not. Developed countries have not directly or indirectly funded any further nodule-related research in the Cook Islands since 2000, and none is planned in the future. There is little doubt that if the Cook Islands wants information to make decisions on the impacts of mining it needs to rely on expeditions by Exploratory Licensees, involving independent researchers.

Some people claim it will take 10 years or more to obtain enough information to make a decision on the acceptability of nodule mining. Where did the idea of 10 years come from? It seems to be based on the UN’s Decade of Ocean Science for Sustainable Development (2021-2030) rather than any information about the possible rate of focused biological research. It is impossible to discuss this ten-year scenario because it is not based on any analysis of actual research expeditions – it is simply a declaration.

I will analyse a research expedition to the CCZ to enable a discussion on the likely duration of focused research in the Central SPB to obtain enough information for a robust EIA on the likely impacts of nodule mining.

One expedition

In 2015 the German RV Sonne spent five weeks in the CCZ undertaking biodiversity and geochemical research at six sites (GEOMAR Report 2015). See lower-right map in Figure 2.

The expedition obtained a large collection of seabed biodiversity specimens and it enabled two important peer-reviewed papers. The first, Vanreusel et al. (2016) on megafauna was discussed above. The second, Volz et al. (2018) analysed biochemical processes in the sediment, included organic carbon, and similar research is needed in the SPB to check and extend the preliminary Japanese 2000 data which showed a low level of organic carbon.

In the CCZ, the RV Sonne’s six research sites were spread over an area of around 400,000km², a little larger than the area of the entire SPB from Penrhyn south to Palmerston and Aitutaki.  See Figure 2, where the CCZ and SPB to the same scale.

The top-right map shows the details of the six days sampling in the Belgian GSR concession focused within an area of 12km². The main benthic sampling included 5x multi‑cores, 5x box‑cores, 4x epibenthic sledgings, 2x amphipod trappings, and ~1km of ROV video of megafauna with some specimen collecting using the manipulator arm and push-corer. The expedition also twice measured the characteristics of the water column from the surface-to-seabed.

In six days, the expedition collected detailed biological and chemical information from the GSR site; the sampling regime was similar in the other five sites widely separated sites.

Imagine the immensely more detailed information that would be obtained by a 5-week RV Sonne expedition focused on a small area, such as the nodule-rich Central SPB, with an area of only 20,000km² (see Figure 2 left map).

Furthermore, contractors will focus their research within their own allocated 20-year mine areas of about 4000km². In this case a single five-week expedition collecting 30 multi-core and 30 box-core samples in addition to five ~1km ROV-video transects would provide very detailed information. And contractors would probably undertake several such expeditions.

Although collecting biological and environmental data for a robust EIA could take as little as a five-week expedition, the analysis of the data would take much longer, probably one or two years. In some cases, it would also be necessary to set up monitoring systems early so they could run for at least a year to measure variability over time.

However, this detailed biological knowledge is only half of the information required to evaluate the likely impacts of precautionary mining. The other half of the equation is the extraction technology and processes that a mining company proposes to use.

Technological research

Based on existing DSM equipment modelling, development and experiments, it seems likely that any large mining company can develop and test nodule extraction technology in two or three years.

If companies undertake the biological and technological research sequentially, it would take four or five years before an EIA could evaluate the impacts of nodule mining. However, if these complementary research programmes were undertaken concurrently, the data for a robust EIA could be available within two or three years.

References available on request.