How Does Anything Survive in a Lake That’s Dry Most of the Time?
This is one of my favourite things to explain on tour, because the answer is genuinely astonishing once you understand it. Lake Eyre is dry for years, sometimes a decade or more, at a stretch. And yet within days of significant flooding, fish and crustaceans appear in numbers that suggest they’ve been waiting the whole time. In a sense, they have.
The Problem These Species Have Solved
Any organism living in a system like Lake Eyre faces an obvious challenge: how do you survive in a body of water that might not exist for years at a time? Most aquatic species can’t simply wait out a drought — they need water continuously to survive. The species that thrive at Lake Eyre have evolved a different strategy entirely.
Brine Shrimp and Diapause
Brine shrimp — small crustaceans well adapted to saline conditions — produce eggs capable of entering a state called diapause, a form of biological dormancy where development essentially pauses entirely. These eggs can survive in a completely desiccated state, embedded in dried lake mud, for years or even decades, waiting for the specific conditions — sufficient water, appropriate salinity — that trigger them to hatch.
When flooding occurs and conditions become suitable, these dormant eggs hatch in enormous numbers almost simultaneously, producing a burst of brine shrimp population that becomes a critical food source for the birds that arrive to breed.
Native Fish and Their Own Strategy
Native fish species like bony bream don’t have the same dormant-egg strategy as brine shrimp, but they persist through drought periods in a different way — surviving in the deeper, more permanent waterholes and refuge pools within the broader Lake Eyre Basin river systems, even when the lake itself is completely dry. When floodwater moves through these systems toward the lake, fish are carried along with it, arriving at the lake as living populations rather than dormant eggs.
Once in the lake’s nutrient-rich floodwater, these fish breed prolifically, taking advantage of a temporary boom in food availability before the water evaporates again.
The Birds That Depend on This Cycle
This entire chain of dormant eggs, sudden hatching, and fish arrival exists to support one of the most remarkable bird breeding events in Australia. Species like the banded stilt time their breeding specifically around inland flooding events, arriving in enormous numbers to take advantage of the sudden abundance of brine shrimp and other food sources. Without the brine shrimp’s diapause strategy, this entire ecological event simply couldn’t happen.
What This Means When You Visit
If you’re at the lake during or shortly after a flood, what you’re witnessing is the visible expression of a biological strategy that took shape over an enormous span of evolutionary time — species that solved the problem of surviving an unpredictable, harsh environment by essentially pausing their own biology until conditions were right. It’s one of the more genuinely remarkable pieces of natural history in this landscape, and it’s easy to miss if you don’t know to look for it.
