[iwr]

Even if predators can't metabolize the mirror molecules, they can still eat them (possibly dying afterwards). So you'd need to release the mirror algae( ?) in very large quantities for them to overcome the predatory pressures in their environment.

It also means that by killing predators (zoo-plankton), mirror algae are creating a niche for standard algae too. So you could end up with a soup of R and L life, but diminished predatory activity.

[stcredzero]

There would be evolutionary pressure for the predators to be able to distinguish the mirror algae and not eat them. Such predators would undoubtedly arise, which would give mirror-algae an evolutionary advantage.

Mirror-algae would only have to be released in large enough quantities to gain a toehold.