a role in the formation of dunes by promoting the accumulation of wind-blown sand. Human impacts Inorganic debris Manmade objects are often washed ashore in the wrack zone, posing a threat to coastal animals. Plastics in particular are the most common form of litter found on beaches, and it is estimated that 46% of shorebirds ingest plastic in their lifetime while 26% experience entanglement. A variety of effects have been observed in animals that ingest plastic, including reduced reproductive success, changes in immune function, and increased mortality. There is also growing evidence suggesting that plastic bioaccumulates through the food web, so predators may be affected by the accumulation of plastic in their prey's diet. Beach raking Sandy beaches are often groomed for aesthetic and recreational value. The removal of organic debris limits habitat and food availability for wrack-associated animals and inhibits the formation of dunes. Shoreline hardening Sea walls and other coastal armoring structures can affect the location of a wrack zone and reduce the accumulation of organic material. This can negatively impact the structure and diversity of coastal habitats. See also References Coastal geography