The lush marshes also rank as one of the earth's most productive ecosystems, creating more organic material per acre than the richest farmland. The marsh grasses are the basic food source in the marsh. Dead marsh grass is broken down by bacteria into detritus . The detritus mixes with algae and other material to create a kind of nutrient rich soup. Marsh inhabitants such as shellfish, along with crabs, worms and other animals survive on this food.
Grasshoppers eat the grasses directly and are in turn eaten by spiders, fish and birds.
Larger birds such as great blue heron, will eat marsh fish and small rodents. Mammals like raccoon will visit the marsh to consume crabs and shellfish. Humans depend on the marsh more than people realize. Two-thirds of all commercial fish and shellfish need the protected coastal marshes to survive. The decrease in fish population is probably due, in part, to the destruction of coastal wetlands like Rumney Marsh.