Reptiles

Polythene bags drifting in ocean currents look much like the prey items targeted by turtles [93-95]; see Figure 2.4. There is evidence that their survival is being hindered by plastics debris [96], with young sea turtles being particularly vulnerable [97]. Balazs [98] listed 79 cases of turtles whose guts were full of various sorts of plastic debris, and O’Hara et al. [99] cited a turtle found in New York that had swallowed 540 m of fishing line. Entanglement in plastic debris, especially in discarded fishing gear, is a very serious threat to marine reptiles. It also affects the survival of sea turtles as there are endangered [97].

Invertebrates

Plastic effects on invertebrates are mainly attributed to microplastics. Various studies have been well documented [3,100-103]. Some of the effects of microplastics on aquatic invertebrates include blockages throughout the digestive system or abrasions from sharp objects resulting in injuries, blockage of enzyme production, diminished feeding stimulus, nutrient dilution, reduced growth rates, lowered steroid hormone levels, delayed ovulation and reproductive failure and absorption of toxins [3]. There is potential for microplastics to clog and block the feeding appendages of marine invertebrates or even to become embedded in tissues [1]. Table 2.5 presents a comprehensive list of evidence of impacts of plastic debris on marine organisms by various studies.

Study

Animal

Encounter Type

Predominant Debris Type

Impact Response

[92]

Grey seals

Entanglement

MF line, net, rope

Constriction

[Ю4]

Manatees

Entanglement

MF line, bags, other debris

Death

[105]

Elephant seals

Entanglement

MF line, fishing jigs

Dermal wound

[1061

Fur seals

Entanglement

Packing bands, fishing gear, other debris

Dermal wound

[1071

Seabirds, pinnipeds

Entanglement

Fishing gear

External wound

[108]

Fur seals

Entanglement

Trawl netting, packing bands

Death

[108]

Fur seals

Entanglement

Trawl netting, packing bands

Reduced population size

[109]

Invertebrates, fish, seabirds, marine mammals

Entanglement

Derelict gillnets

Death

[1101

Seabirds, marine mammals

Entanglement

Plastic, fishing line

Death

[1111

Gorgonians

Entanglement

Fishing line

Damage/breakage

[112]

Sea turtles

Entanglement

Fishing gear

Death

[113]

Whales

Entanglement

Plastic line

Dermal wound

[114]

Whales

Entanglement

Plastic line

Dermal wound

[104]

Manatees

Ingestion

MF line, bags, other debris

Death

[115]

Sea turtles

Ingestion

MF line, fish hooks, other debris

Intestinal blockage, death

[П61

Penguins

Ingestion

Plastic, fishing gear, other debris

Perforated gut, death

[117]

Lugworms (laboratory)

Ingestion

Microplastics

Biochemical/cellular, death

[95]

Sea turtles

Ingestion

Plastic bags, ropes

Gut obstruction, death

[H8]

Seabirds

Ingestion

Plastic particles, pellets

Perforated gut

[119]

Fish (laboratory)

Ingestion

Nanoparticles

Biochemical/cellular

[1201

Seabirds

Ingestion

Plastic pellets, foam

Biochemical/cellular

(Continued)

Study

Animal

Encounter Type

Predominant Debris Type

Impact Response

[107]

Seabirds, pinnipeds

Ingestion

Fishing hooks

Internal wound

[90]

Sperm whale

Ingestion

Identifiable litter items

Gastric rupture, death

[74]

Seabirds

Ingestion

Plastic fragments, pellets, identifiable litter

Gut impaction, ulcerative lesions

[87]

Sperm whales

Ingestion

Fishing gear, other debris

Gastric rupture, gut impaction, death

[12Ц

Copepods (laboratory)

Ingestion

Micro- and Nanoplastics

Death

[122]

Fish (laboratory)

Ingestion

Microplastics

Biochemical/cellular

[123-125]

Fish (laboratory)

Ingestion

Microplastics

Biochemical/cellular

[72]

Birds (laboratory)

Ingestion

Microplastics

Reduced organ size

[112]

Sea turtles

Ingestion

Marine debris

Gut obstruction

[3]

Lugworms (laboratory)

Ingestion

Microplastics

Biochemical/cellular

[1261

Mussels (laboratory)

Ingestion and gill uptake

Microplastics

Biochemical/cellular

[127]

Epi benthic mega fauna

Interaction (contact)

Plastic bottles, glass jars

Altered assemblage

[128]

Sessile invertebrates (coral reef)

Interaction (contact)

Lobster traps

Altered assemblage

[129]

Assemblage on sediment

Interaction (contact)

Plastic litter

Altered assemblage

[130]

Sessile invertebrates (coral reef)

Interaction (contact)

MF line, lobster trap, hook and line gear

Tissue abrasion

[131]

Sessile invertebrates (coral reef)

Interaction (contact)

Hook and line gear

Tissue abrasion

[1321

Seagrass

Interaction (contact)

Crab pots, tires, wood

Breakage, suffocation, death

[133]

Sea turtles

Interaction (obstruction)

Waste, medical waste

Reduced population size

[134]

Ghost crabs

Interaction (obstruction)

Beach litter, mostly plastic

Reduced population size

[134]

Ghost crabs

Interaction (substrate)

Beach litter, mostly plastic

Altered assemblage

[101]

Marine insects

Interaction (substrate)

Microplastics

Increased population size

Source: From Law KL. Annu Rev Mar Sci 2017, 9, 205-229.

Note: This table is based on analysis by [135] for publications through the year 2013, extracting studies for plastic marine debris only. Abbreviation: MF, monofilament line.

Impact on plant communities is minimal compared to threats to animals. Natural flotsam, of both marine and terrestrial origin (seaweeds and plants), together with jetsam of indeterminate sources, tends to accumulate along high tide strandlines, where it is commonly known as the “the wrack” [59]. These areas are often ephemeral, dynamic and seasonal environments and also tend to accumulate significant quantities of manufactured materials, in particular, those also made of plastic and other indestructible materials [59]. As a consequence, wrack environments are commonly unsightly, and the demands of local authorities to clean up the mess are frequent and can be expensive [137,138]. Maximum impacts on the floral communities are, however, observed in the form of microplastics. Recent studies (such as [3]) emphasized the important role of microplastics as they are easily ingestible by small organisms, such as plankton species, and form a pathway for contaminants to enter the food web.

 
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