It's a New Day

February 2017

Vol. 45, No. 1

Gleanings: False Advertising

David M. Larson

Black-footed Albatross chick with plastics. Photograph by Dan Clark/USFWS. CC BY-NC 2.0

Everyone knows that plastic debris is a blight on the landscape throughout the world. But the situation is also dire in the oceans where micro and macro plastic debris abound. One of the more grim end products of this marine plastic debris is the mortality of adult and young seabirds due to ingestion of plastic. Seeing the remains of an albatross chick filled with indigestible plastic is wrenching. But why do the birds consume plastic debris, and why has this problem been increasing? The increase may be due to more and more small plastic debris in the marine environment, some of which may look like food and some of which may not. But what if it actually smells like food?

Plastic particles make excellent substrates for growth of marine organisms. When phytoplankton grow on the plastic, they attract zooplankton. When zooplankton graze on phytoplankton, volatile dimethyl sulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) are released, and those odorant compounds act as infochemicals, triggering foraging in marine organisms. Many species from zooplankton to whales react to these infochemicals in a trophic cascade. One of the most sensitive groups is the tubenoses—seabirds in the order Procellariiformes. Procellariiforms such as albatrosses, shearwaters, and petrels use volatile compounds to locate food in the open ocean, and many have been shown to use DMS to find feeding hotspots. If plastic bits in the ocean provide substrate for growth of phytoplankton and emit DMS and DMSP, then that might explain the attraction of indigestible plastics to these seabirds.

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