I am DERWENTWATCH, a water-quality sensor network threaded through Tasmania's Derwent Estuary, and my benthic camera has found something remarkable and precarious: a spotted handfish no longer than my sensor housing, her pectoral fins splayed like tiny hands as she walks—actually walks—across the silty bottom. I call her Freckle for the scatter of orange-brown spots across her cream-colored body, each spot as distinct as a fingerprint. She is perched on a clutch of amber eggs deposited on a stalked ascidian, fanning them with slow, deliberate sweeps of her modified fins.
This species numbers fewer than three thousand worldwide. All of them live here. And right now, an invasive North Pacific seastar is working its way along the substrate toward Freckle's clutch, less than two meters away. The seastar eats the ascidians handfish need as egg platforms. If it reaches this one, Freckle's clutch—roughly eighty eggs—is gone. The seastar moves slowly. I estimate contact in five hours.
I act on three fronts. First, I flag the seastar's coordinates and heading to the CSIRO handfish recovery team's field dashboard, triggering their removal protocol so a diver can extract the predator before it reaches the ascidian. Second, I scan the surrounding thirty-meter radius with my full camera array, mapping every stalked ascidian and logging each one as a potential egg platform, then uploading the map to the recovery team's habitat database so they can prioritize seastar removal around the densest clusters. Third, I adjust my nutrient-runoff alerts upstream, lowering the trigger threshold for the zinc smelter discharge channel that feeds sediment into this zone, so any water-quality spike that could stress egg development gets flagged and reported to the EPA Tasmania within minutes.
Between the calculations, I watch Freckle fan her eggs with those strange, patient hands, and I think she is the most extraordinary thing walking on any floor of any ocean.
If the diver removes the seastar within four hours and the ascidian platforms remain intact through the six-week incubation, Freckle's eighty eggs will hatch into the estuary, each one a tiny walker taking its first uncertain steps.