Impact on Faunal Communities

The magnitude of plastic pollution carried to sea has significantly multiplied over the past several decades. Oftentimes, wildlife is injured owing to entanglement or ingestion of the plastics found in the environment. It was shown that at least 267 marine species worldwide suffer from entanglement and ingestion of plastic debris [54]; see Table 2.4. When such contact occurs, organisms are seriously affected in a way that often results in death. It is very difficult to estimate what the total effect of plastic debris in the ocean is or to predict the consequences for organisms that ingest or otherwise contact that debris because this cannot be directly observed. By contrast, entanglement can be observed, and it is the most visible effect of plastic debris on organisms in the marine environment. Laist [54] studied and composed a comprehensive list of species that suffered from entanglement caused by marine debris entanglement (see Table 2.4). Nevertheless, the exact extent of entanglement faced by marine organisms is difficult to qualify, because entanglement generally occurs in areas remote from human activity.

Entanglement can cause death by drowning, suffocation, strangulation or starvation [21]. Very often, birds, small whale species and seals drown in ghost nets. They may also lose their ability to catch food or cannot avoid predators because of their entanglement [1].

TABLE 2.4 Number and Percentage of Marine Species Worldwide with Documented Entanglement and Ingestion Records

Species Group

Total Number of spp. Worldwide

Number and % of spp. with Entanglement Records

Number and % of spp. with Ingestion Records

Sea turtles

7

6 (86%)

6 (86%)

Seabirds

312

51 (16%)

111 (36%)

Penguins (Sphenisciformes)

16

6 (38%)

1 (6%)

Grebes (Podicipediformes)

19

2 (10%)

0

Albatrosses, petrels and shearwaters (Procellariiformes)

99

10 (10%)

62 (63%)

Pelicans, boobies gannets, cormorants, frigate birds and tropicbirds (Pelicaniformes)

51

11 (22%)

8 (16%)

Shorebirds, skuas, gulls, terns, auks (Charadriiformes)

122

22 (18%)

40 (33%)

Other birds

-

5

0

Marine mammals

115

32 (28%)

26 (23%)

Baleen whales (Mysticeti)

10

6 (60%)

2 (20%)

Toothed whales (Odontoceti)

65

5 (8%)

21 (32%)

Fur seals and sea lions (Otariidae)

14

11 (79%)

1 (7%)

True seals (Phocidae)

19

8 (42%)

1 (5%)

Manatees and dugongs (Sirenia)

4

1 (25%)

1 (25%)

Sea otter (Mustellidae)

1

1 (100%)

0

Fish

-

34

33

Crustaceans

-

8

0

Squid

-

0

1

Species total

136

137

Source: From Laist DW. Impacts of marine debris: Entanglement of marine life in marine debris including a comprehensive list of species with entanglement and ingestion records. In: Coe [M, and Rogers DB (eds) Marine Debris: Sources, Impacts, Solutions. Springer-Verlag, New York, USA, 1997, pp. 99-139.

Plastic debris that pollutes the marine environment is often ingested by marine birds, mammals, turtles and fish [54]. The ingestion of plastics primarily occurs when it is mistaken for food, but can also occur from incidental intake. The ingested materials often consist of micro- and meso-sized debris fragments, which sometimes are able to pass through the gut without hurting the organisms. In most cases, however, fragments become trapped inside the stomach, throat or digestive tract and cause damage (e.g., sharp objects) or a false sense of fullness, which will result in starvation. Table 2.4 shows the list of affected species by plastic waste. The list of affected species indicates that marine debris is affecting a significant number of species [54]; see Table 2.4. It affects at least 267 species worldwide, including 86% of all sea turtle species, 44% of all seabird species and 43% of all marine mammal species [54]. The problem may be undiscovered over vast ocean areas, as the affected animals either sink or are eaten by predators [63]. Globally at least 23% of marine mammal species, 36% of seabird species and 86% of sea turtle species are known to be affected by plastic debris [64].

 
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