Gleanings: False Advertising

Tue, 31 Jan 2017 00:00:00 GMT

Savoca and coworkers (Savoca, et al., 2016) tested this potential trophic cascade by a series of experiments. First, they exposed virgin plastic spheres to an oceanic environment in the photic zone for three weeks, and then they tested the spheres for DMS. Using gas chromatography, there was no detectable DMS coming from samples of virgin high-density polyethylene, low-density polyethylene, or polypropylene beads. However, the marine-exposed bead samples of all three plastic types emitted DMS at concentrations detectable by procellariiforms.

The authors then did a meta-analysis of 55 studies on 25 species of procellariiforms and found a statistically strong relationship between DMS sensitivity and consumption of plastic by these birds. They went on to mathematically model this relationship, which suggested that DMS-sensitive species ingest plastic five times as frequently as nonsensitive species. There is a strong positive relationship between DMS-sensitivity and birds that nest in burrows, as opposed to those that nest on the surface, so the authors used burrow-nesting as a proxy for DMS-sensitivity. This expanded their analysis to 62 procellariiform species. Within this expanded species set, model analysis suggested burrow-nesting tubenoses ingested plastic three times more frequently than surface-nesting species, roughly consistent with the meta-analysis.

This study suggests that DMS-sensitive, tubenosed seabirds are particularly susceptible to ingesting plastic in the marine environment because of the aroma of DMS from the phytoplankton that grows on the plastic. Mediation efforts might be aimed at reducing the plastic load in the oceans—estimated in 2014 at over 250 million metric tons—or at producing plastics that do not support phytoplankton growth. Clearly the problem of plastic ingestion is not limited to seabirds, since many studies have raised the alarm over the increased plastic load in marine fish, marine mammals, and sea turtles. Other studies have demonstrated the importance of DMS in foraging cascades in marine organisms from zooplankton to cetaceans. Seabirds are perhaps the most at risk, with clear negative consequences due to gastrointestinal obstruction and chemical toxicity.

Finally, I found the collaborations in this study to be perfect, pairing biologists with the Department of Viticulture and Enology, all at University of California Davis. It all comes down to the volatiles and the bouquet.

Reference

Savoca, M.S., M.E. Wohlfeil, S.E. Ebeler, and G.A. Nevitt. 2016. Marine Plastic Debris Emits a Keystone Infochemical for Olfactory Foraging Seabirds. Science Advances 2: e1600395. Accessed November 24, 2016.

David M. Larson, PhD, is the Science and Education Coordinator at Mass Audubon’s Joppa Flats Education Center in Newburyport, the Director of Mass Audubon’s Birder’s Certificate Program and the Certificate Program in Bird Ecology (a course for naturalist guides in Belize), a domestic and international tour leader, Vice President of the Nuttall Ornithological Club, and a member of the editorial staff of Bird Observer..

February 2017

Gleanings: False Advertising

Reference