In The World Without Us, Alan Weisman describes the fates of manmade objects and structures on a planet devoid of humans; the most disturbing chapter, in my opinion, is the one entitled “Polymers Are Forever”. Mr. McGuire in The Graduate was correct: plastics are the future, at least from an environmental perspective. Last week I summarized two papers that described methods for quantitating user and industrial plastics in the surface waters of the ocean, and on beaches. Another way of measuring the plastics problem is to determine how much of the material is actually ingested by marine animals.
Blight and Burger (1997) used seabirds that had accidentally drowned in a drift-net fishery, and examined stomach contents, with particular attention to plastic particles. All of the surface-feeding procellariiformes (albatross, petrel, fulmar, storm-petrel) had ingested plastic particles, as had 75% of the shearwaters. In the Stejneger’s Petrel, small Leach’s and Fork-tailed Storm-Petrels, and one of the Sooty Shearwaters examined, the amount of plastic present in the gizzard or proventriculus may have been sufficient to interfere with digestion. Three species of alcids (Common Murre, Xantus’ Murrelet, Rhinoceros Auklet) contained no plastics, whereas two puffin species (Tufted and Horned) had ingested plastic particles; all of these birds are pursuit divers, and were not expected to have eaten floating plastic.
Leach’s Storm-Petrel (Oceanodroma leucorhoa)
Photo: C. Schlawe, via Wikipedia
Cadée (2002) employed a unique sampling method to estimate the effects of styrofoam and plastic debris on North Sea birds: he examined plastics collected on a Dutch coast beach for peckmarks, which might indicate that birds mistook these items for natural cuttlebone. This researcher noted first that many cuttlebone “shells” washed up on beaches showed peckmarks, presumably from seabirds seeking calcium carbonate supplements. He examined over 100 pieces of styrofoam and floating plastic, and found peckmarks on 80% of these. Cadée emphasized the need to decrease the amounts of plastic litter in the oceans, as almost 100% of Fulmars examined in this region had ingested plastic particles.
And, finally, I follow the trail of plastic debris to a third continent, with a paper by Copello and Quintana (2003) on the Southern Giant Petrel, along the Patagonian coast of Argentina. These investigators emptied the stomach contents of petrel chicks, by massaging the throats and tummies of the birds, and then categorized and weighed plastic and other debris in the regurgitated samples. They found on average 2.0 grams of litter, mostly plastic, in these samples, indicating that a substantial proportion of the chicks’ diet is contaminated with plastic debris. Although serological studies of adult Southern Giant Petrels in two Patagonian colonies indicate that overall health is good, the researchers pointed out that ingested plastics can clog the gizzards of young birds, and expose them to high concentrations of absorbed PCBs and pesticides. Copello and Quintana suggested that the petrels may have obtained the plastic debris while feeding on the waste from high seas fisheries.
Blight, L.K., Burger, A.E. (1997). Occurrence of plastic particles in Seabirds from the Eastern North Pacific. Marine Pollution Bulletin 34(5), 323-325.
Cadée, G.C. (2002). Seabirds and floating plastic debris. Marine Pollution Bulletin 44, 1294-1295.
Copello, S., Quintana, F. (2003). Marine debris ingestion by Southern Giant Petrels and its potential relationships with fisheries in the Southern Atlantic Ocean. Marine Pollution Bulletin 46, 1513-1515.