Comment by moh_maya | Hacker News Reader

Comment by moh_maya | Hacker News Reader

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Not really. Deep sea mining on the floor will kick up sediments, that will probably affect growth of plankton, which form one of the foundations of the ocean ecosystem. Also related to what I've quoted below, you'll probably end up releasing a lot of minerals into the ocean water that drive algal blooms.

"Bottom trawling also stirs up the sediment at the bottom of the sea. The resulting undersea plumes of “suspended solids” can drift with the current for tens of miles from the source of the trawling, introducing turbidity throughout the water that inhibits the transfer of light down to the depths where it is needed for photosynthesis in plankton, sea kelp and other undersea plants that serve as the basis for the marine food chain. Also, ocean sediments serve as natural safe resting places for many persistent organic pollutants (such as DDT and PCBs). Dredging these sediments up effectively reintroduces such toxins into the water where they are unwittingly absorbed and consumed by the fish we eat and other marine life already trying to cope with otherwise compromised undersea habitats. The sediment plumes also reintroduce nutrient solids from agricultural and other practices, increasing demand for oxygen in the water (causing algae blooms) and contributing to the outbreak of ocean “dead zones” devoid of marine life." [1]

[1] https://www.scientificamerican.com/article/saving-deep-ocean...

The link is talking about damaging coral. Coral requires sunlight. I'm not sure what they mean by "deep sea", but if it's got sunlight it's not what's under discussion here. They're not pulling valuable fish species like tuna out of the hadal zone. It's confusing, to countenance the current abuses like those described in that link but use them to criticize a completely unrelated activity.

Not all coral species need light. There are "coral forests" adapted to cold waters. Lophelia builds "deep-water briars" there. They are super-mega-slow growing.

And of course there are comercial species of very expensive yummy crustaceans living there. A couple of trawls and all is lost for the next thousands of years.

1000 m < 5500 m

What we do on the surface has far more effect on these species than does the researchers' mud-digging at far greater depths.

Hem, nope, because you are messing with the deep water layers. You are messing with the marine snow, temperature, salinity and oxygen at a local scale. Research activity is one thing. Mining the sea bottom for rare matherials is a totally different situation, even if wouldn't be so hugely expensive.

You're assuming that, but that isn't how energy works in the ocean. Stuff in the water falls down. Disturbances at 5500 m and deeper do not affect distant (hundreds of nautical miles) seafloor life at far shallower depths. If a mud-collection operation transported lots of abyssal mud to the surface and then dispersed it into the water column, it would affect pelagic life in that location, but not coral. Coral do not grow at these depths. Anyway, any feasible rare earth operation would need to "refine" the mud before hauling it to the surface, as described in TFA, so the mud wouldn't be dispersed into the water column anyway.

Actually even Lophelia should be considered in the category "too deep to worry about", because as you pointed out they don't photosynthesize. They don't interact with us, and they don't interact with anything we interact with.

> If a mud-collection operation transported lots of abyssal mud to the surface and then dispersed it into the water column, it would affect pelagic life in that location, but not coral

First of all, you are forgetting that all corals are pelagic species.

The "too deep to worry about" and "don't interact with anything we interact with" is also wrong both as concept and also as fact.

Lophelia reefs are the coral reefs of temperate areas. Can be found between 30 and 3000 m deep.

Until relatively recent times, we didn't even knew that we have coral reefs in UK, Norway or Canada. Still we don't know a lot about this places, but coral reefs are among the most rich ecosystems in the planet supporting an astonishing amount of biodiversity. As any other reef we know that they provide refuge for a (still poorly know, but probably very high) number of crustaceans, other invertebrates and fishes. It seems that Is an important refuge for sharks for example. Sharks play a role in keeping healthy marine ecosystems.

Next Cape Cañaveral growths a similar (much shallower) cold reef in a relatively narrow band that was the first marine area closed for research in USA. The Oculina Bank area of particular concern. Many fisheries depend on the Oculina reef. Their damage was directly linked with the demise of Florida's grouper fisheries for example.

We are also also slowly understanding how complex are soft bottom ecosystems. Much more complex that we previously though. Under the silt there are the equivalent of fields of grasses and shrubs but carved on negative space.

Is not just sand, is also 4000 years old antipatharians, is really smart predators that hold the key to made robots coated in one of the most resistent bio-matherials known in the planet. One that is able to stand high pressures, but that is also light, and that can also generate ultra-fast movements enduring well the mechanical damage

In silt bottoms we can found animals able to literally make the water boil around them. They can raise the temperature of a tiny amount of water to around 4000 degrees C. And they can do it in less than a second. Not, I'm not joking.

And there is also the "too deep to worry about" and "don't interact with us" small Aequorea, that blew our minds and changed forever how we, humans, do modern biosanitary research in the entire planet.

Lots and lots and lots of valuable things for humans.

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