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Home , Plastic, Plastic pollution

Vol. 37: 295303. 1987 MARINE ECOLOGY - PROGRESS SERIES Published May 6 Mar. Ecol. Prog. Ser.

REVIEW

Marine birds and

Marie Y. Azzarello & Edward S. Van Vleet

Department of Marine , University of South Florida, 140 Seventh Avenue South, St. Petersburg, Florida 33701,USA

ABSTRACT: The intrinsic properties and widespread presence of plastic particles in the marine environment have profound effects on birds inhabiting the world's oceans. Industrial and user- composed of , , , styrofoam, and are the most prevalent forms of plastic . Their dispersal and accumulation, in average of 1000 to 4000 pieces km-2, are controlled by surface currents, wind patterns, and different geographic inputs. in the order ProceUariiformes are most vulnerable to the effects of plastic ingeshon due to their smaller and their inability to regurgitate ingested plastics. Planktivores have a higher incidence of ingested plastics than do piscivores as the former are more likely to confuse plastic pellets with copepods, euphausiids, and cephalopods. Hence, &et may be a major factor determining the quantity of plastic ingested. Physiological effects related to the ingestion of plastics include obstruction of the gastrointestines and of subsequent passage of food into the intestines, blockage of gastric enzyme secretion, diminished feeding stimulus, lowered steroid levels, delayed ovulation and reproductive failure. As plastic manufacture and use increases and subsequent disposal at sea becomes more extensive, the impact of dscarded plastic on birds inhabiting the marine environment may also be expected to increase.

The beauty and geiiius of a work of ari nldy be ment, and specifically to marine birds. Distinct reconceived, though its first expression be methods of foraging, breeding and molting as as destroyed; a vanished harmony may yet again inspire well-defined distribution patterns of seabirds result in the composer; but when the last individual of a race of varying degrees of vulnerability to . living beings breathes no more, another heaven and Some seabirds are more susceptible in their breeding another earth mustpass before such a one can be quarters, others where they molt, and still others in again. places where they spend their term of immaturity. To WiLliarn Beebe evaluate the environmental threat posed by discarded 1877-1962 plastics, it is crucial to understand their role in ecology. A comprehensive review of plastic ingestion by marine birds has been provided by Day et al. (1985). INTRODUCTION Here we expand on several points made by Day et al., and include several species and aspects not discussed Although plastics have been produced in large in detail in their review. quantities since the end of World War 11, it was not until the 1970's that the existence of widespread plas- tic pollution of oceanic waters was discerned. Accord- AND SOURCES OF PLASTIC ing to the National Academy of (1975) POLLUTION approximately 4.5 X 104 metric tons of plastic are discarded at sea annually. Since the production of non- Much has been published in the last 10 yr on the biodegradable plastics and subsequent waste disposal prevalence of plastics as a in the marine practices have been increasing worldwide, it is likely environment. A large body of evidence has been that levels of will continue to increase gathered indicating widespread marine contamination and pose an escalating threat to the marine environ- by plastic jetsam discharged from (Wong et al.

O Inter-ResearchIPrinted in F. R. Mar. Ecol. Prog. Ser. 37: 295-303, 1987

1974) and by polyethylene and polypropylene indu- fishing nets, Lines, and buoys were discarded by fish- strial pellets discharged in waste effluents (Carpenter ing fleets into the world's oceans (National Academy of & Smith 1972, Carpenter et al. 1972, Colton et al. 1974, Sciences 1975). In the Bering Sea alone, about 145000 Gregory 1977, Moms 1980). Plastics present a problem pieces of net fragments per year originate from the in the environment because they float, are non-biode- fishing industry (Merrell 1984). Since Japan has been gradable, and only slowly degrade upon exposure to the principal user of monofilament gill nets in the radiation. Extension of the semce life of Bering Sea and North Pacific Ocean, Merrell (1984, some plastics has been made possible recently by 1985) suggests that the majority of nets and floats incorporation of ultraviolet light stabilizers and anti- washed onto Alaskan originate from Japanese oxidants. This has led to a corresponding increase in fisheries. Gill net floats represented the greatest con- the persistence of plastics and their inherent problems stituent of plastic on Alaskan beaches in in the environment (Dixon & Dixon 1981). Merrell's study. Plastics found at sea may be classified into 2 major types based on their origin. 'User-plastics' are most conspicuous and consist of plastic directly DISTRIBUTION OF PLASTICS IN THE OCEAN used by man, such as plastic , , , pack- aging materials, ropes and nets. These objects are Plastic pellets have been reported in average routinely discarded from commercial and fishing ves- densities of 1000 to 4000 km-' on the surfaces of the seis (Dixon & Dixon 1981). although some originate North Atlantic, South Atlantic, and Pacific Oceans from rivers and ocean dumping of land-generated lit- (Carpenter & Smith 1972, Carpenter et al. 1972, Colton ter. Larger plastic items often break up to form smaller et al. 1974, Moms & Hamilton 1974, Wong et al. 1974, fragments that are more commonly observed in the Gregory 1977, Shiber 1979, Day 1980). Most oceanic oceans (van Franeker 1985). areas investigated, however, have been in the vicinity The second, less conspicuous, type of plastic of coastal industrial sources, near major shipping originates from industrial sources. These formulated lanes, or influenced by wind and current conditions and compounded plastics generally take the form of more Likely to retain and accumulate floating material small cylindrical disks having a diameter of less than than to disperse it (Monis 1980). Hence these estimates 4 mm, although spherical and rectangular granules are Likely to be higher than the oceanic average. also occur. These small plastic particles are the indu- Areas which have shown the highest concentration strial bulk material in which plastics are manufactured of plastics in coastal waters along the Atlantic sea- and transported prior to their transformation into user- board of are those where most plastic plastics by remelting and employing additives (van and processing companies are located Franeker 1985). Colton et al. (1974) suggest that the in southern New England and the middle Atlantic widespread distribution of plastic in rivers. states (Carpenter et al. 1972, Colton et al. 1974). Plastic estuarine, and coastal waters of the is the sheets and pellets were the most abundant and most result of improper wastewater disposal in the plastics widely dispersed particles collected in continental industry. Polystyrene spherules from factory effluents shelf waters between Virginia and Rhode Island, with may be canied down rivers, with some settling out at polystyrene spherules present in concentrations up to the mouths of the rivers and others being transported 14 m-3 (Carpenter et al. 1972). Sheets and pellets were into coastal waters (Hays & Cormons 1974). The most also the only forms of plastics found in appreciable probable cause of compounded plastics in the open quantities in shelf waters south of Cape Hatteras, and ocean is routine waste &sposal at sea by indi- in most stations in the Sea and Antilles vidual vessels (Colton et al. 1974). current area (Colton et al. 1974). observations show that the plastic composi- Carpenter & Smith (1972) demonstrated the presence tion of marine Litter is more diversified nearshore and of small plastic particles in the surface of the Sargasso that it includes primary and secondary packaging, Sea with an average concentration of 3500 pieces km-' cargo-associated and -room wastes, and fishing occumng over a lateral distance of 1300 km. Lower (Dixon & Dixon 1981). Presumably when fishing concentrations were detected in and directly east of the nets were made of plant fibers they disintegrated Gulf Stream, just south of Cape Hatteras and in the rapidly after being lost or discarded at sea. However, Yucatan Channel. No plastic debris was bscovered at with widespread use of more durable netting, stations in the Straits of Florida, in the southeastern the situation has deteriorated. Small and large frag- Gulf of Mexico, or in coastal and Gulf Stream waters ments of monofilament net are now becoming an south of Cape Lookout, North Carolina (Colton et al. integral part of jetsam washed up on beaches (Bourne 1974). 1977). In 1975, approximately 13172 metric tons of An early account of plastic spherules collected in Azzarello & Van Vleet: Ma.rine birds and plastic pollution 297

British coastal waters by Morris & Hamilton (1974) collected during both years were similar except that indicated that these particles were negatively buoyant plastic was much more prevalent in 1975. It is sus- (having a of 1.08) and frequently contained pected that much of this debris was discarded from occluded solid phases together with vacuoles. Infrared fishing vessels because debris-containing areas corres- confirmed that these plastics were ponded closely to southern Bering Sea fishing zones. composed of a modified polystyrene containing In the southern Pacific, plastic pellets collected on approximately 13 % of a -butadiene . New Zealand beaches were primarily polyethylene In a later study of plastic on beaches of the United and polypropylene (Gregory 1977). Pellet abundance, Kingdom, Dixon & Dixon (1981) reported that frag- though highly variable, was greatest near important mented plastic was found in 77.8 % of the transects New Zealand industrial centers, exceeding 40000 sampled (compared with frequencies of 34.2 % for , pieces m-'. Even on beaches far-removed from poten- 62.7 % for ). Plastic pieces were found in 94 % of tial industrial contaminants, significant quantities of their transects taken on French and Danish beaches. pellets were detected. Substantial plastic accumulation has also been noted Previous studies have demonstrated a high degree of along the beaches of (Shiber 1979). patchiness in plastic distribution at sea. This patchi- Polyethylene and polypropylene pellets were found ness is attributable to currents, winds, and different to be principal contaminants of the sea surface in the geographic inputs (Shaw & Mapes 1979). Wong et al. Cape Basin area of the South , an area (1974) observed that in the western Pacific, wind stress quite remote from any obvious source of such debris surface eastward to about 170" W (Moms 1980). Morris described these plastic particles where both a weakening in wind stress and a change as primarily hard white or colorless spherules or in the prevailing winds to a southward direction pellets having a diameter of 3 to 5 mm. All had well- occurs. At 143"W, in a region of zero annual wind rounded ends suggesting extensive weathering. stress, an accumulation of plastic was observed (Wong In a survey of plastic particle pollution in the north- et al. 1974). In other areas, such as the Gulf of Alaska, em Pacific off central , Baltz & Morejohn surface currents play a more dominant role in the (1976) found mostly small polyethylene cylinders, dispersal of plastic particles (Day 1980). Morris (1980) although styrofoam, synthetic sponges, and pieces of has suggested that plastics are being transported glob- flexible food wrap and rigid plastic were collected as ally by oceanic current systems, and as a result have well. Most of the plastic cylinders had rounded rather now become as ubiquitous a contaminant of the than sharp edges, signifying substantial wear (Colton world's oceans as tarballs. et al. 1974) which may have occurred either on the h open ocean waters, denser p!astic debris (e.9. beach or in the stomachs of birds (Baltz & Morejohn polystyrene-styrene ) gradually to the 1976). denser, cold mid-water layers where it attains neutral Wong et al. (1974) sampled surface waters along buoyancy and remains suspended in the water column. latitude 35"N near the California , then north This is likely to result in a substantial underestimate of along 125"W to Victoria, British Columbia. Small (0.1 the amount of plastic in the oceans since most studies to 0.5 cm) round colorless plastic pellets weighing 20 report concentrations of plastic in surface waters only to 50 mg each were found in 21 of 23 tows. The average (Morris 1980). concentration was 0.3 mg m-' with a maximum con- centration of 3.5 mg m-', or 34000 pieces km-2. As part of an environmental assessment program of FATE OF PLASTICS the Alaskan continental shelf (60" 00' N, 147O30' W to 5g038' N, 140°00' W), Jewett (1976) reported pollutants Although plastic debris is generally quite resistant to recovered from several benthic trawls. Of the stations microbial or chemical degradation, many plastics are sampled, 57 % were contaminated with refuse consist- transformed from their original nature in the marine ing primarily of plastic materials such as brown or environment. Based upon observations of plastic col- green refuse bags, pieces of clear plastic (bait lected on west European beaches and in waters of wrappers), and plastic used as cargo binding western , Dixon & Dixon (1981) deduced the material. Much of this plastic debris was of Japanese fate of plastic bottles in the marine environment. They and Korean origin. suggest that bottles made from the major therrnoplas- A benthic trawl of the southeast Bering Sea during tics, especially high density polyethylene, are photo- 1975-76 by Feder et al. (1978) brought up man-made degradable at the air-sea interface. debris consisting primarily of metal, rope (synthetic), produces in plastics and subsequent plastic, and , with minor amounts of rubber, wood, fragmentation, generally within 2 to 3 yr following cloth, and products. The various classes of debris their discard at sea (Dixon & Dixon 1981). Mar. Ecol. Prog. Ser. 37: 295-303, 1987

Major packaging materials have Table 1. Common and scientific names of marine birds refer- recently been developed with enhanced degradability red to in text (after Harrison 1983) upon exposure to ultraviolet light. By combining exist- ing compounds with photosensitive additives or by Common name Genus and species incorporating minor amounts of CO- contain- ing photosensitive groups, these treated plastics can be Order: Procellariiformes made to degrade faster in the environment. Reports Black-footed Diomedea nigripes Diomedea imm utabds confirm that a subjected to this process will be Kerguelan petrel Pterodroma brevirostris reduced to fragmentable condition within 3 mo com- White-chinned petrel Procellaria aequinoctids pared to 3 yr for its unmodified counterpart (Dixon & Soft-plumaged petrel Pterodroma mollis Dixon 1981). Although plastics with enhanced degrad- Atlantic petrel Pterodroma incerta Wilson's petrel Oceanites oceanicus abfity might well reduce the persistence of these Common diving-petrel Pelecanoides urinatrix materials in the marine environment, any such advan- Broad-billed prion Pachyptda vitta ta tages could be offset by increases in the quantities Greater sheanvater Puffinis gra vis used and therefore discarded at sea. In addition, Sooty sheanvater Puffinis griseus extending the service life of some plastics has recently Manx shearwater Puffinis puffin's Litte shearwater Puffinis assimilis been made possible by incorporating ultraviolet light North Atlantic fulmar Fulmarus glacialis stabilizers and anti-oxidants during the manufacturing British storm-petrel Hydrobates pelagicus process (Dixon & Dixon 1981). Hence the overall Leach's storm-petrel Oceanodrorna leucorhoa degradabihty of plastics currently being discharged to Fork-tded storm-petrel Oceanodroma furcata Grey-backed storm petrel Carrodra nereis the ocean is still unclear. With regard to fishing nets, White-bellied storm-petrel Fregatta grallana Wehle & Coleman (1983) suggest that submerged nets White-faced storm-petrel Pelagodroma marina may remain in the ocean for up to 50 yr. These nets are Order: Charadriiformes highly resistant to processes of degradation in the Red phalarope Phalaropus fulicarius environment due to their minimum exposure to heat, Parakeet auklet Cyclorrh ynchus psittacula light, and abrasion. Horned puffin Fratercula corniculata

CLASSIFICATION AND CHARACTERISTICS terns and waders. Birds of the order Procellariiformes OF SEABIRDS tend to accumulate more plastic than do other species. However, quantities in the gizzard may vary greatly The fact that seabirds are highly diverse in their among species and individuals (Day 1980, Furness behavior and adapt differently to the marine environ- 1985a). , terns, skuas, and waders, as well as ment makes it somewhat difficult to characterize them other Charadriiformes, habitually regurgitate indigest- as a group. Some sojourn to inland waters and open ible parts of their food items, such as shell and fish country for at least part of the year, and retreat to the bone (Hays & Cormons 1974). Procellariiformes, how- sea only during inclement seasons, while others are ever, have a constriction between the gizzard and year-round marine inhabitants. Many birds are typi- proventriculus, which makes it more difficult for cally marine and come ashore exclusively to roost and qzzard contents to be expelled (Furness 1985a). breed (Bourne 1976). Alexander's classic compendium, Although some Procellariiformes frequently regurgi- The Birds of the Ocean (1928) classifies penguins, tate portions of their stomach contents, the regurgita- , 3 farmlies of petrels, tropic birds, frigate tion often consists only of stomach oil and there may be birds, some pelicans, the gannets and boobies, some a tendency for these buds to retain hard indigestible cormorants and shags, the phalaropes, skuas or objects such as plastics (Rothstein 1973). The low jaegars, gulls, terns, skimmers and auks or alcids as possibility of regurgitation of plastic particles, together seabirds. It is also possible to include the divers, with a smaller gizzard in which to accommodate them, grebes, and sea ducks all of which have a tendency to causes Procellariiformes to be especially susceptible to breed inland yet winter offshore (Bourne 1976). the effects of plastic pellet ingestion (Furness 1985a). Of particular interest to this paper are the 2 orders most extensively researched: Procellariiformes and Charadriiformes (Table 1). The former includes the MODES OF INGESTION following: British storm-petrels, prions, Leach's storm- petrels, white-chinned petrels, greater shearwaters, Ashmole (1971) classified seabirds on the basis of the sooty shearwaters, Manx shearwaters and fulmars. The method by which they ingest food. These methods latter group comprise the red phalaropes, skuas, gulls, include pursuit diving, surface-seizing, dipping, Azzarello & Van Vleet: Manne birds and plastic pollution 299

plunging and piracy. In what appears to be the mosl ships in an effort to feed on dumped waste material, comprehensive work to date on plastic ingestion by unlike Wilson's petrels Oceanites oceanicus, a related marine birds, Day (1980) reported that 15 of 37 species species (Petersen 1947). The absence of plastic in com- of marine birds in Alaska contained plastic particles. mon diving petrels deserves mention as this species is The highest incidence of plastic was found in seabirds strikingly disparate to other small Procellariiformes. Of feeding by pursuit-diving (26 %) whereas 16 O/O of the 19 diving petrels examined by Furness (1985a), 5 Alaskan birds feeding by surface-seizing, 9 O/O feeding contained euphausiids with which brown plastic by dipping, and none of those feeding by plunging or pellets could readily be confused. It is possible that piracy contained plastic. The absence of plastic in because this species feeds by underwater pursuit-div- birds feeding by plunging and piracy is reasonable, as ing, it does not select plastics floating on the surface, as plungers generally retrieve prey items beneath the other petrel species do (Furness 1985a). water's surface, where less plastic is normally found. Birds feeding by piracy retrieve food dropped by other birds, food which is almost always fish (Ashmole 1971) OBSERVATIONS OF SEABIRDS IMPACTED and apparently contains little or no plastic (Day 1980). BY PLASTICS Several known and potential prey items naturally inhabit the epipelagic zone, where plastics might be The fact that marine birds swallow indigestible mistaken for prey or ingested along with them (Day objects is well-documented. Kenyon & Kridler (1969) 1980). Common white, light brown, and red plastic examined the body contents of 100 Laysan albatross particles found at or near the water's surface often Diomedea immutabilis carcasses collected along the resemble the planktonic larvae of a number of crusta- beaches and reefs of . All foreign non-food ceans as well as the adults of other species (Mauchline items were collected and tabulated (Table 2). Only 9 1980, Raymont 1983). Birds feeding predominantly on crustaceans or cephalopods generally have signifi- Table 2. Indigestible material in 100 Laysan albatross car- cantly higher frequencies of ingested plastic than do casses collected along Hawaiian beaches and reefs (from piscivores (Day 1980). Light brown plastic particles Kenyon & Kridler 1969; reprinted with permission of the found in the surface layers of the ocean may also American Ornithologists Union Publishing Co.). F: frequency resemble eggs of many pelagic fishes and crustaceans. of occurence; G: greatest no. in one bird It is interesting to note that Colton et al. (1974) origi- nally classified plastic particles caught in neuston tows Buoyant items Number Weight (g) F G as fish eggs. Thus, birds may also be 'mistahng' these particles for food (Day 1980). Plastics buried within Pumice 546 1063 85 93 egg masses have been recovered from regurgitations of Plastic Laysan albatross (Hamson & Hida 1980). Based on Caps (bottle) 83 69 Misc. (toys) 157 111 these considerations, the relationship to prey type may (polyethylene) l 3 actually be a better predictor of expected plastic inges- Total 24 1 183 74 8 tion than feeding method or foraging , due to the resemblance of plastic particles to prey items (Day Nuts 12 63 12 1 1980). The black-footed albatross Diomedea nigripes has been reported to scavenge trash thrown overboard birds were void of objects. When placed in water, while following ships for long distances (Fisher 1973). 99.4 O/O of the items recovered from the dead birds were Plastics may be ingested by this method, but no buoyant. Approximately 30 % of these were plastic. specific reports have confirmed this mode of ingestion Pieces of plastic typifying those contained in the (Pettit et al. 1981). Similarly, this method of ingestion albatross carcasses were scattered about the beaches. has been proposed by Furness (1983) for white-chinned Although at first it may seem that the beaches were the petrels, greater shearwaters and sooty shearwaters, 3 origin of indigestible items found in young albatross, species which feed primarily by surface-seizing and this is unlikely since albatross rarely ingest food or scavenging (Ashmole 197 1). other items from the shore. It is more probable that the Due to their inability to dive, Leach's storm-petrels plastic items were retrieved at sea by the parents and consume indigestible objects floating within a few subsequently passed on with regurgitated food to their centimeters of the ocean's surface (Palmer 1962). It is young (Kenyon & Kridler 1969). likely that these particles were broadcast over the open In a recent study of seabirds from Gough Island ocean near ships or dumps, since Leach's (40°21'S, go53'W), South Atlantic Ocean, Furness petrels infrequently feed in inland waters or follow (1985a) determined that the most highly contaminated 300 Mar. Ecol. Prog. Ser. 37: 295-303, 1987

species included greater shearwaters and white-faced EFFECTS OF PLASTICS ON SEABIRDS storm-petrels (with up to 53 particles per bird). To a lesser degree broad-billed prions, white-bellied storm- Most investigators strongly caution that seabirds are petrels, gray-backed storm-petrels, a Tristan skua, lit- likely to be injured by ingested plastic. Consumption tle shearwater, Kerguelan petrel, Atlantic petrel, and of plastic particles could result in blockage or internal soft-plumaged petrel were also found to be contami- injury, although some seabirds may eventually regur- nated with plastic. The most contaminated birds con- gitate plastic pellets with other indigestible matter, tained plastic equal to 96 % (white-faced storm-pet- thereby reducing harmful effects (Hays & Cormons

rels) and 81 O/O (greater shearwater) of their relaxed 1974, and many others). gizzard volume. Although smaller species tended to Post-mortem examination of 4 young albatross con- contain smaller particles, the smaller species appear to firmed that regurgitation of plastics from adult to chick ingest more plastic than larger ones relative to body occurs in this species (Pettit et al. 1981). Plastics were size. In a similar study, Furness (1985b) detected no found in each chick. In one young bird, the large parhcles in the intestines of any birds he examined. quantity of indgestible matter contributed to intestinal Though it is possible that plastic particles may be obstruction, while another bird with bulky plastics in slowly worn down in the gizzard until small enough to the proventriculus had ulcerations in the mucosa. The pass through the intestines, there are no reports con- retention of relatively small, smooth-surfaced plastics firming that this actually takes place. Moreover, size indicate that even small, hard objects do not ordinarily frequency distribution implies that it probably does not pass through the adult bird's proventriculus and occur since small parhcles were rarely found in the gizzard to enter the lower digestive tract. Plastic par- birds' yzzards (Furness 1985b). ticles were never observed in the excreta of this Plastic particles and pellets have been reported in species (Pettit et al. 1981). several other studies of surface waters and birds off Birds that do not regurgitate solid matter can southern (Moms 1980, Ryan 1985) and in the accumulate plastic which may interfere directly with South Atlantic (Bourne & Imber 1982, Furness 1983). their digestion. The presence of non-food items in The fact that plastic particles were found in stomachs birds' may not only cause gastrointestinal of Antarctic and sub-Antarctic species is of parbcular blockage (Day 1980), but may also be directly related concern as it indicates that pollution is now commonly to feeding stimulus and activity (Sturkie 1965). Hunger found in what has long been believed to be a relatively and satiety are controlled by receptors in the bird's pristine environment. hypothalamus where stimuli perceived by the central Stomach contents of 22 fulmars collected in 1980 at nervous system regulate food intake. Those factors Bear Island (74" 24' N, 19" 00' E) and 29 fulmars col- stimulating appetite (hunger) include contraction of an lected in 1983 at Jan Mayen (71" 00' N, 09" 00' W) were empty stomach, low temperatures, and the sight of analyzed by van Franeker (1985). Although far- food; whereas those factors inhibiting appetite (satiety) removed from industrial areas or major shipping include dehydration and distention of the stomach routes, approximately 80 O/O of the fulmars at both or intestines. Large quantities of plastic in a bird's islands contained plastics. Plastic particles were also stomach could therefore depress feeding activity by found in 39 % of greater sheanvater stomachs sustaining stomach distention or by preventing examined at Brier Island (44" 15'N, 66"22'W), and in stomach contraction, signifying 'satiety' to the hypo- 75 % of those investigated from Placentia Bay (ca thalamus (Sturlue 1965). Birds collected from Gough 47" 00' N, 54" 30' W), eastern (Brown et al. Island in whlch plastic pellets were found in the 1981). Similarly, 8 % of sooty shearwater stomachs gizzard invariably lacked fresh food in the proven- dissected at Brier Island and 5 % at Placentia Bay triculus (Furness 1985a). Moreover, the presence of a contained plastic. Plastic ingestion by marine birds large number of particles in the stomach may impede appears to be very widespread in the North Atlantic. the secretion of gastric enzymes or the movement of Ingestion of plastic by seabirds has been confirmed food into the small intestine (Day 1980). Plastic inges- for a number of other species: fork-tailed storm-petrels tion may also be detrimental to reproduction, since Oceanodroma furcata, homed puffins Fratercula cor- DDT, DDE, PCB's and other chlorinated hydrocarbon niculata and parakeet auklet Cyclorrhynchus psitta- pollutants associated with plastics may lower steroid cula in the Aleutian Islands (Ohlendorf et al. 1978). hormone levels causing delayed ovulation (Peakall adult and nestling Leach's storm-petrels Oceanodroma 1970). leucorhoa in Newfoundland and New Brunswick, Connors & Smith (1982) report the incidence of plas- Canada (Rothstein 1973) and in regurgitated and tic in a small but unique sample of migrating red tern pellets from Long Island Sound, (Hays phalaropes Phalaropus fulicarius, small sandpiper-hke & Cormons 1974). shorebirds adapted for swimming in surface layers and Azzarello & Van Vleet: Ma~rine birds and plastlc pollution 301

grazing upon zooplankton. These authors classified fat and may be readily assimilated from the ingested plas- deposition in the phalaropes on a scale from 1 (no fat) tics (Aldershoff 1982). Carpenter et al. (1972) found to 5 (excessive fat) without knowledge of stomach that plastics recovered from marine surface waters contents. These values ranged from 1.5 to 3.5 (Table 3). contained polychlorinated (PCB's) in a con- centration of 5 ppm. Since PCB's are not added during Table 3. Weight, fat condition and plastic particle occurrence the manufacture of , these authors sug- in 7 red phalaropes, ordered by fat class (from Connors & gested that the probable source was from Smith 1982; reprinted with permission of Pergamon Press Ltd) ambient seawater. Based upon their similar physico- chemical properbes, other toxic organochlorines (such Sex Weight Fat Plastic as DDT or DDE) may also be associated with oceanic class No. Total % of plastic debris. of weight stomach Studies concerning the effects of plastic pollution on pieces (g) volume marine birds are relatively new. Although few defini- M 39.6 1.5 6 0.048 13.0 tive studies have been reported, we have tried to eluci- M 39.2 1.8 6 0.025 11.3 date several potential hazards associated with the F 40.4 2.0 2 0.005 1.4 ingestion of plastics. Although many of these potential F 46.3 2.2 8 0.044 21.2 hazards Lie in the realm of conjecture, we believe that M 43.9 2.5 14 0.047 19.2 M 45.0 3.0 4 0.031 11.9 it is important to work toward prevention or prediction F 50.1 3.5 0 0.000 0.0 of these problems before the actual effects have been realized. Adverse biological consequences resulting from the present levels of plastic in the oceans appear Although only one stomach contained recognizable to be insignificant for most marine organisms com- food items (barnacle larvae and hyperiid amphipods), pared to the deleterious effects of other contaminants 6 of 7 stomachs were contaminated with plastic debris. such as wastes, , or other chemical Most of the recovered plastics were polyethylene residues. Marine birds may be an exception to this 'nibs', an intermediate stage in the plastic manufactur- rule. Escalating production of plastics, compounded by ing process (Colton et al. 1974); although a few parti- improper waste disposal practices, will predictably cles were pieces of styrofoam. The results of Connors & result in increases in the concentrations of these parti- Smith (1982) indicated that fat class was negatively cles in rivers, estuaries and the open ocean. Birds correlated with the number of pieces of plastic. Since inhabiting the marine environment might be expected fat condition plays a major role in determining flight to suffer the greatest consequences from this contami- range capabihties and possibly breeding success in nation. this long-distance migrant, the potential effect carries considerable biological significance (Connors & Smith 1982). Plastic contamination may produce physiologi- LITERATURE CITED cal effects which threaten survival or reproductive success in regions far-removed from pollution sources Aldershoff, W. G. (1982). Gezondheidsaspecten van PVC voor (Holmes 1966, McLean 1969, McNeil & Cadieu 1972, levensmiddelen. Plastlca 35: 58-60 Ashkenazie & Safriel 1979, Connors & Smith 1982). Alexander, W. B. (1928). The buds of the ocean. Pitman. London Wallace (1985) reports that seabirds encountering Ashkenazie, S., Safriel, U. N. (1979). Time-energy budgets of discarded nets face possible . In their obser- the semi-palmated sandpiper Calidris pusdla at Barrow, vations of net debris outside North Pacific fishing areas Alaska. Ecology 60: 783-799 during 1978, Jones & Ferrero (1985) reported that 99 Ashmole, N. P. (1971). Seabird ecology and the marine environment. In: Famer, D. S., Kmd, J. R. (ed.) Avian seabirds were entangled in a 1500 m gill net. Simi- biology, Vol. 1. Academic Press, New York, p. 223-286 larly, Tull et al. (1972), Shaughnessy (1980), Fowler Baltz, D. M,, Morejohn, G. V, (1976). Evidence from seabirds (1982), Piatt & Reddin (1984) and Piatt et al. (1984) of plastic particle pollution off central California. Western report seabird entrapment in abandoned fishing nets Birds 7: 111-112 throughout the world's oceans. Bourne, W. R. P. (1976). Seabirds and pollution. In: John- ston, R. (ed.) Marine pollution. Academic Press, London, Other adverse effects may also result from plastic p. 403-502 ingestion. Although industrial plastic granules are nor- Bourne. W. R. P. (1977). Nylon netting as a hazard to birds. mally considered to be composed of biologically stable Mar. Pollut. Bull. 8: 75-76 plastic , large amounts of additives including Bourne, W. R. P., Imber, M. J. (1982). Plastic pellets collected by a prion on Gough Island, Central South America. Mar. softeners, colorants, and anti-oxidants are often Pollut. Bull. 13: 20-21 employed during the transformation from granules to Brown, R. G. B., Barker, S. P,, Gash, S. P,, Sandeman, E. E. user-plastics. These additives can be toxic in nature (1981). The foods of Great and Sooty Shearwaters, Puffinus Mar. Ecol. Prog. Ser. 37: 295-303, 1987

gravis and P. griseus in eastern Canadian waters. Ibis 123: diversity of Arctic sandpipers near Barrow, Alaska. Ph.D. IS30 thesis, University of California, Berkeley Carpenter, E. J.. Anderson, S. J., Harvey. G. R., Miklas, H. P., Mauchline, J. (1980). The biology of mysids and euphausiids. Peck, B. B. (1972). Polystyrene spherules in coastal waters. Adv. Mar. Biol. 18: 1-681 Science 178: 749-750 McNeil, R., Cadieux, F. (1972). Fat content and flight-range Carpenter. E. J., Smith, K. L. (1972). Plastics on the Sargasso capabilities of some adult and fall migrant surface. Science 175: 1240-1241 American shorebirds in relation to migration routes on the Colton, J. B., Knapp, F. D., Burns, B. R. (1974). Plastic particles Atlantic coast. Naturaliste can. 9: 58!+606 in surface waters of the northwestern Atlantic. Science Merrell, T R., Jr. (1984). A decade of change in nets and 185: 491-497 plastic litter from fisheries off Alaska. Mar. Pollut. Bull. Connors, P. G., Smith, K. G. (1982). Oceanic plastic particle 15: 378-384 pollution: suspected effect on fat deposition in Red Merrell, T. R., Jr. (1985). Fish nets and other plastic litter on Phalaropes. Mar. Pollut. Bull. 13: 18-20 Alaska beaches. In: Shomura, R. S., Yoshida, H. 0. (ed.) Day, R. H. (1980). The occurrence and characteristics of plas- Proc. Workshop on the Fate and Impact of tic pollution in Alaska's marine birds. M.S. thesis, Univ. of 27-29 November 1984, , Hawaii. U.S. Dept. Alaska Commerce, NOAA Tech. Memo. NMFS, NOAA-TM- Day, R. H., Wehle, D. H. S., Coleman, F. C. (1985). Ingestion of NMFS-SWFC-54, p. 160-182 plastic pollutants by marine birds. In: Shomura, R. S., Morris. A. W., Hamilton. E. S. (1974). Polystyrene spherules in Yoshida, H. 0. (ed.) Proc. Workshop on the Fate and the Bristol Channel. Mar. Pollut. Bull. 5: 26-27 Impact of Marine Debris, 27-29 November 1984, Hono- Moms, R. J. (1980). Plastic debris in the surface waters of the lulu, Hawaii. U.S. Dept. Commerce, NOAA Techn. Memo. South Atlantic. Mar. Pollut. Bull. 11: 164-166 NMFS, NOAA-TM-NMFS-SWFC-54, p. 344-386 National Academy of Sciences (1975). Marine litter. Asses- Dixon, T. R., Dixon, T. J. (1981). Marine litter surveillance. sing Potential Ocean Pollutants. A Report of the Ocean Mar. Pollut. Bull. 12: 289-295 Affairs Board, Commission on Natural Resources. NAS- Feder, H. M., Jewett, S. C., Hilsinger, J. R. (1978). Man-made NRC, Washington, D.C. debris on the Bering Sea floor. Mar. Pollut. Bull. 9: 52-53 Ohlendorf, H. M., ksebrough, R. W., Vermeer, K. (1978). Fisher, H. I. (1973). Pollutants in the North Pacific Albatross. Exposure of manne birds to environmental pollutants. Pacif. Sci. 27: 220-225 U.S. Dept Interior, Fish and Service, Wildhfe Fowler, C. W. (1982). Interactions of northern fur seals and Research Report 9, Washington, D.C. commercial fisheries. Trans. N. Am. Wildl. Nat. Resour. Palmer, R. S. (1962). Handbook of North American birds, Conf. 47: 278-292 Vol. 1. Yale Univ. Press, New Haven Furness, B. L. (1983). Plastic particles in three Procellaiiform Peakall, D. B. (1970). p,p'DDT: effect on Ca metabolism and seabirds from the Benguelan Current, S. Africa. Mar. concentration of estradiol in the blood. Science 168: Pollut. Bull. 14: 307-308 592-594 Fumess, R. W. (1985a). Ingestion of plastic particles by sea- Petersen. R. S. (1947). A field guide to the study of birds. birds at Gough Island, South Atlantic Ocean. Environ. Houghton Mifflin Co.. Boston Pollut. Series A 38: 261-272 Pettit, T. N., Grant, G., Whittow, G. C. (1981). Ingestion of Furness, R. W. (1985b). Plastic particle pollution: accumula- plastic by Laysan Albatross. Auk 98: 839-841 tion by Procellariiform seabirds at Scottish colonies. Mar. Piatt, J. F., Nettleship, D. N., Threlfall, W. (1984). Net-mortal- Pollut. Bull. 16: 103-106 ity of common murres and Atlantic puffins in Newfound- Gregory, M. R. (1977). Plastic pellets on New Zealand land, 1951-81. In: Nettleship, D. N., Sanger, G. A., beaches. Mar. Pollut. Bull. 8: 82-84 Springer, P. F. (ed.) Marine birds: their feeding ecology Harrison, C. S., Hida, T. S. (1980). The status of seabird and commercial fisheries relationships. Can. Wildl. Sen. research in the northwestem . In: Grigg. Spec. Publ., p. 196-207 R. W., Pfund, R. T. (ed.) Proc. Status Resource Investiga- Piatt, J. F., Reddin, D. G. (1984). Recent trends in the west tions in the Northwest Hawaiian Islands. Sea Grant, Univ. Greenland salmon fishery, and implications for thick- of Hawaii, Hawaii billed murres. In: Nettleship, D. N., Sanger, G. A., Harrison, P. (1983). Seabirds - an identification guide. Springer, P. F. (ed.) Marine birds: their feeding ecology Houghton Mifflin Company, Boston and commercial fisheries relationships. Can. Wildl. Serv. Hays, H., Cormons, G. (1974). Plastic particles found in tern Spec. Publ., p. 208-210 pellets on coastal beaches and at factory sites. Mar. Pollut. Raymont, J. E. G. (1983). Plankton and productivity in the Bull. 5: 44-46 oceans. Zooplankton, Vol. 2, 2nd edn. Pergamon Press, Holrnes, R. T. (1966). Breehng ecology and annual cycle New York adaptations of the red-backed sandpiper (Calidris alpina) Rothstein. S. I. (1973). Plastic particle pollution of the surface in northern Alaska. Condor 86: 3-46 of the Atlantic Ocean: evidence from a seabird. Condor Jewett, S. C. (1976). Pollutants in the northeast Gulf of Alaska. 75: 344-346 Mar. Pollut. Bull. 7: 169 Ryan, P. G. (1985). Plastic pollution at sea and in seabirds off Jones, L. L., Ferrero, R. C. (1985). Observations of net debris Southern Africa. In: Shomura, R. S., Yoshida, H. 0. (ed.) and associated entanglements in the North Pacific Ocean Proc. Workshop on the Fate and Impact of Marine Debris, and Bering Sea, 1978-84. In: Shomura, R. S., Yoshida, H. 27-29 November, Honolulu, Hawaii. U.S. Dept. Com- 0. (ed.) Proc. Workshop on the Fate and Impact of Marine merce, NOAA Tech. Memo. NMFS, NOAA-TM-NMFS- Debris, 27-29 November 1984, Honolulu, haw^. U.S. SWFC-54, p. 523 Dept. Commerce, NOAA Tech. Memo. NMFS, NOM- Shaughnessy, P. D. (1980). Entanglement of Cape Fur Seals TM-NMFS-SWFC-54, p. 183-196 wlth man-made objects. Mar Pollut. Bull. 11: 332-336 Kenyon, K. W., Kridler, E. (1969). Laysan Albatross swallow Shaw, D. G., Mapes, G. A. (1979).Surface circulation and the indgestible matter. Auk 86: 339-343 distribuhon of pelagic tar and plastic. Mar. Pollut. Bd. MacLean, S. F., Jr (1969). Ecoloqcal determinants of species 10: 160-162 Azzarello & Van Vleet: Marine birds and plastic pollution

Shiber, J. G. (1979). Pellets on the coast of Lebanon. Mar. environment: a review. In: Shomura, R. S., Yoshida. H. 0. Pollut. Bull. 10: 28-30 (ed.) Proc. Workshop on the Fate and Impact of Marine Sturkie, P. D. (1965). Avian physiology. Cornell Univ. Press, Debris, 27-29 November. Honolulu, Hawaii. U.S. Dept. New York Commerce, NOAA Tech. Memo. NMFS, NOAA-TM- Tull, C. E., Germain, P,, May, A. W. (1972). Mortality of thick- NMFS-SWFC-54, p. 259-277 billed murres in the west Greenland salmon fishery. Wehle, H. S., Coleman, F. C. (1983). Plastics at sea. Natural Nature, Lond. 241: 271 Hist. 92: 2&26 van Franeker, J. A. (1985). Plastic ingestion in the North Wong, C. S., Green, D. R., Cretney, W. J. (1974). Quantitative Atlantic Fulmar. Mar. Pollut. Bull. 16: 367-369 tar and plastic waste distributed in the Pacific Ocean. Wallace, N. (1985). Debris entanglement in the marine Nature, Lond. 247: 3C-32

This review was submitted to the ehtor; it was accepted for on February 26, 1987