>> Can you name even one organism that needs biodiversity to survive?
>>
>Humans, for all their ingenuity, would be hard-pressed to survive with
>no biological material other than other humans to live off....
There's a big distinction between low biodiversity and low biomass.
Polar seas have low biodiversity, for oceans, but are extremely
productive during the summer. Our own farms are exceedingly low
in biodiversity, but breathtakingly productive nonetheless.
The biomass we survive on comes mostly from our own farms. The only
major sources of wild biomass for food we still have is fish, and
it appears that is rapidly coming to an end and being replaced by
fish farms.