Add to this that life in darkness sustained by microbes consuming a rock surface will be rather slow. Because any fast processes would just flash out after a boom/bust cycle or two. And presumably not just slow in terms of no cheetah vs antelope racing, but also much slower than out in the sun in generational turnover.

I wonder how big that cave system is, as in number of barley connected caverns. There might have been quite a few cycles one cavern flashing out and then slowly getting repopulated from the neighboring cavern(s). The "magical" balance we admire in nature isn't a miracle, it's the result of endless series of failure.