Aquatic animals spring to life like magic when rainwater collects in the sandstone potholes of the Colorado Plateau’s high deserts. These temporary pools range from a few inches to 50 feet deep and may last only a short while before they evaporate.
Pothole shrimp have ingenious survival strategies, some of which are well known, like their accelerated life cycles, and eggs that lose 90% of their water, yet remain viable for years. What puzzled scientists was how these shrimp can survive for generations when storms drop only enough rain to awaken the eggs, but the pothole evaporates before the next generation of eggs appears.
In 2021 ecologist Tim Graham partnered with high school student James Davis to solve this survival mystery. They based the study on previous research on shrimp in African ephemeral pools.
Graham and Davis collected their shrimp near Moab, placing males and females together into water-filled beakers. When eggs were laid, they removed the shrimp and allowed the eggs to dry out. Later they rewetted the eggs, caught the emerging hatchlings, and allowed the remaining unhatched eggs to dry, repeating this cycle several times.
Some clutches of eggs took five wet/dry cycles to completely hatch. The requirement of some eggs for multiple wettings prior to hatching saves them for rainier days, so new generations of shrimp can survive a series of scant rainstorms and droughts.
And humans can help, by not walking, bicycling, or driving through dry desert potholes. They may look empty, but they’re full of life.
This Earth Note was written by Elizabeth Blaker and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
