Yes and in the meantime sea creatures that rely on sight will starve, and the ocean will absorb more heat from the sun. This will further speed up its destruction while causing more catastrophic weather events on the surface.
Calm down with the hyperbole. Catastrophic weather events, my lord.
Concern for the planet and climate is a worthy cause and ought not to be discredited by obvious nonsense like this. Extreme reactionary climate conservatism is ultimately self-defeating, much like it's less sexy social conservatism cousin.
Sea floor mining will happen at 200m - 6500m deep. The recently granted exploration license for the Clarion-Clipperton zone is at 4000-5500m deep. There's very little life that deep, and certainly no sunlight to get absorbed by murkier water.
But as there's no way to prevent sediment from polluting large areas of the sea, the depth at which mining occurs is irrelevant. And companies will mine at whatever depths make money.
Still, it's nice to just dismiss it as hyperbole instead of thinking we need to take serious action to prevent further damage to our planet.
Absolutely nothing to be concerned about.