This claim is the opinion of Hans Olav Hide, chair of Loke Marine Minerals.
The basis of the claim is that there needs to be an increase in production of minerals such as nickel, cobalt, and lithium in order to meet the needs for clean energy technology such as batteries. The claim by Loke's chair is that deep-sea mining is the solution to meeting this demand for minerals, rather than the current method of sourcing the materials from China.
It is uncertain the effect deep-sea mining can have on the ecosystem as it is a new practice. There are no global rules for deep-sea mining but the UN backed International Seabed Authority can give exploration licenses for the mining.
An article from Forbes says there is a potential for deep-sea mining to be less destructive than mining on land which can lead to deforestation and impact water usage.
The Forbes article says that deep-sea mining occurs in the aphotic zone of the ocean where light does not reach and there is little biodiversity. The article also referenced a study from MIT where they found 92-98% of sediment from mining re-settled or remained 2 meters above the seabed.
The Financial Times article referenced in the Mastodon post ends with the following quote from Nick Popovic, head of copper and zinc trading at the company Glencore, which highlights the uncertainty in the new field of mining.
"The problem with deep-sea mining is that it’s so early in the game that without any meaningful examples, I would personally struggle to assess it"