At the two sites, there will be six plots each 1m squared in area. The enclosures will be composed of wooden stakes and screening all spray-painted green before being placed in the field. The height of the pins will not exceed the height of the Spartina and will not be visible from the channels because of their distance from shore. Each month the Spartina in each pin will be measured to test the effects of the three different plots: (1) artificially increased Littorina populations,(2) Littorina populations of zero, and (3) a control population.