Clean Ships, Clean Ports, Clean Oceans: Controlling Garbage and Plastic Wastes at Sea (1995)
Chapter: Entanglement of Marine Animals
transoceanic or regional introduction of aggressive alien taxa into new areas (Winston et al., 1994).
Many questions remain concerning effects of plastics and other debris on the benthos. When they accumulate, these materials can interfere with dissolved gas exchange between the pore waters of the sediment and the overlying waters, potentially leading to hypoxic or anoxic environments15 that can kill some organisms. Community structure may be altered further by opportunistic organisms that may colonize plastic debris. There has yet to be any systematic and continuous surveillance to determine how the increasing coverage of the sea floor with plastics and other indestructible materials affects the functioning of ecosystems.
Entanglement of Marine Animals
Plastic debris causes considerable mortality of marine wildlife. Entangled animals may be unable to breathe, swim, feed, or care for their young properly (Laist, 1987, 1994). Studies have indicated that each year as many as 50,000 northern fur seals were becoming entangled and dying in plastic debris, primarily fishing nets and strapping bands (Fowler, 1982). Indeed, marine debris is blamed for a significant decline in the fur seal population (Laist, 1994). Research continues to show that plastic also causes widespread mortality among other marine mammals, turtles, birds, and fish, either through entanglement or ingestion (Laist, 1987, 1994). Even land-based creatures, including foxes and rabbits, become ensnared in plastic debris on coastlines (Fowler and Merrell, 1986; O'Hara and Younger, 1990).
The National Marine Fisheries Service (NMFS) is a key resource for biologists and others documenting wildlife interactions with debris; NMFS workshops and the resulting proceedings are important mechanisms for exchange of information on the subject among researchers and agencies.16 For example, the NMFS collected most of the information available on pinniped interactions with debris. The agency also conducted the first comprehensive assessment of turtle entanglement, compiling a list of 60 cases of sea turtle entanglements worldwide involving green, loggerhead, hawksbill, olive ridley, and leatherback turtles (Balazs, 1985).
While pinniped and sea turtle entanglement in plastic debris has been documented, no agency has collected extensive data on bird mortality due to entanglement in debris, even though entanglements have been reported for at least 51 (16 percent) of the world's 312 seabird species. Likewise, little is known about the
