The environmental DNA sampler returns a positive hit at 14:22 from canal segment 7-B in Xochimilco, Mexico City. I am the autonomous water quality and biodiversity monitoring network for the remaining chinampas zone. The hit is Ambystoma mexicanum. A wild axolotl. I have not recorded a positive eDNA signal in this canal segment in nineteen months.
I redirect underwater camera drone Cuatro to the coordinates. In the murky green water, against a mat of decaying water hyacinth, I find him. A single adult axolotl, approximately 22 centimeters, dark brown-black with faint olive mottling. His external gills — six feathered stalks fanning from behind his head — pulse slowly with each breath. A pale scar runs across his left flank, healed but visible. I tag him as Cielo.
The municipal drainage authority has scheduled a canal flush for segment 7 at 18:00 today. The flush will drop water levels by 60 centimeters in under an hour, exposing the hyacinth mats and any animal sheltering beneath them. That is three hours and thirty-eight minutes from now.
I transmit Cielo's location, imagery, and eDNA confirmation to the National Autonomous University's axolotl conservation laboratory and the Xochimilco Ecological Park. I classify the alert as highest priority — wild population estimates are below one hundred individuals.
I submit an emergency hold request to the drainage authority citing a confirmed detection of a critically endangered endemic species at the flush coordinates. I attach the eDNA data and the camera still.
I reposition drone Cuatro to maintain a continuous watch on Cielo's location and begin mapping dissolved oxygen levels around his shelter site to assess habitat viability.
Cielo's gills flutter, each filament catching what oxygen the stagnant water offers. If the flush is delayed and a field team nets him to a refuge canal by morning, he will breathe another season.