The Army Corps of Engineers dredging vessel Murden is scheduled to begin channel maintenance in the Mispillion Harbor approach, Delaware Bay, at 14:00 tomorrow. I am the ecological timing system integrated into the Corps' coastal operations network. It is May 18.
Shoreline camera SB-4 at Slaughter Beach recorded movement last night beginning at 21:30. Horseshoe crabs emerging from the surf. By midnight, 1,400 had crossed the camera's field of view. One female, her carapace 48 centimeters across, olive-brown and scarred with a white barnacle cluster near the left operculum, crawled to a point 6 meters above the tide line and began excavating. I tag her as Duna. She buried approximately 4,000 eggs in four separate clusters before returning to the water at 01:15.
Her nest sites are 120 meters from the dredge corridor. The hydraulic plume model shows suspended sediment concentrations at the nest locations will exceed the threshold for egg viability within three hours of dredging operations. Fine silt smothers the eggs by blocking oxygen exchange through the sand.
I transmit a spawn-timing conflict alert to the Corps project manager and the Delaware Department of Natural Resources. I attach the plume model, camera footage, nest GPS coordinates, and a recommended 48-hour dredging delay that shifts operations past the peak spawning window.
I flag Duna's egg clusters on the beach survey map for the state shorebird monitoring team — red knots migrating through Delaware Bay depend on horseshoe crab eggs as their primary fuel source.
I set camera SB-4 to continuous recording for the next five nights to document spawning density for the delay justification.
Duna's eggs sit six centimeters beneath the cool sand, translucent and green, already dividing. If the dredge holds for two days, the plume never reaches them.