Finally, draining marshes increases the direct runoff flowing to the ocean. Marshes are able to absorb toxic chemicals that leach into waterways from pesticides used in agriculture, as well as industrial pollutants. Without the marshy sponge, runoff flows directly to the ocean, often creating coastal "dead zones" where there is little life below the water's surface. The frequent dead zones that regularly develop around the Chesapeake Bay and the Gulf of Mexico are not only the result of agricultural and industrial runoff, but a lack of marshland to combat such runoff.