A spill of fuel oil which occurred near the Wild Harbor salt marsh in 1969, affected and contaminated salt marshes with up to 6000 micrograms of oil (per gram) of wet mud. It contaminated also the local populations of Uca pugnax. Concentrations of oil that spilled greater than 1000 micrograms (ppm) were directly toxic to adults, 100 to 200 ppm, on the other hand, were toxic to juveniles, so how much more its effect to salt water marsh plants. They were not able to recover from toxins.