After K-Pg impact darkness, what did ocean recovery lean on before normal food webs?

Answer: Bacterial prey base

Deep coral forests — Deep coral forests are real ecosystems, but they are not the reset button described for K-Pg plankton recovery. Corals with photosymbionts can be vulnerable to light loss, and deep corals do not replace the ocean's microscopic production base. The early recovery story is much smaller and stranger.

Bacterial prey base ✓ — Bacterial prey base is the right idea. The Science Advances study argues that impact darkness temporarily reset the marine food chain toward bacteria-dominated prey, then mixotrophic plankton helped rebuild production. The memorable twist is that the ocean's comeback began less like a green field and more like microbes eating microbes.

New whale browsers — New whale grazers are impossible for this moment: whales evolved tens of millions of years after the K-Pg event. This wrong choice is useful because it exposes a scale error. The first recovery mechanism was microscopic and nutritional, not a quick replacement by large modern animals.