An oil spill occurred in 1969 near the wild harbor salt marsh. researchers have found that several species of salt water marsh plants no longer grow in this area. what is the most likely explanation for these results? all of the original species have hybridized with new ones. pollution from the spill has changed the composition of the marsh. carbon dioxide levels have decreased over the years. the scientists measured the plants incorrectly.

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. 

more words for this could be abiotic and biotic

abiotic: living organisms within an ecosystem

biotic: non-living organisms within an ecosystem