A Galápagos penguin is perched on the molten rock of the Isabela Islands. The authors captured this photo during a 2021 expedition to collect microplastics in the Galápagos Marine Reserve. Credit: Karly McMullen
Key points:
- Microplastics have been found in seawater samples from an island that has nearby Galápagos penguin colonies.
- The unique model not only revealed the presence of the plastics, but also showed the potential for bioaccumulation in the penguins’ food web.
- The model predicts contamination across the penguins’ prey organisms, resulting in Galápagos penguins showing the highest level of microplastics per biomass.
Researchers are using the endangered Galápagos penguin (Spheniscus mendiculus) as an indicator species to trace how deeply microplastic bioaccumulation has entered the food web in the isolated Galápagos Islands.
In a new study in PLoS One, scientists collected seawater samples from Santa Cruz Island—a human-populated island—that has nearby Galápagos penguin colonies. They quickly discovered microplastics, particles with a size from 1 micron to <5 millimeters, in the samples.
Then, using the Galápagos penguin diet (barracuda, sardine, herring, salema, and anchovy), as well as penguin scat, researchers tracked the bioaccumulation potential of microplastics in the penguins’ food web through a unique food web model. They also applied a wider model for Bolivar Channel Ecosystem—between Fernandina and Isabela islands—and part of the penguin’s habitats, located at the western regions of the Galápagos Islands.
The model predictions showed a rapid increase in microplastic accumulation and contamination across the penguins’ prey organisms, resulting in Galápagos penguins showing the highest level of microplastics per biomass, followed by barracuda, anchovy, sardine, herring, and salema and predatory zooplankton.
“The model predictions highlight the accumulation behavior and residence time of microplastics in the gut,” said Karly McMullen, first author and a former MSc student at the Institute for the Oceans and Fisheries at the University of British Columbia. “With microplastics emerging as a prominent ocean pollutant, entering the environment every day, there is a growing concern for marine fauna and coastal wildlife, particularly if this anthropogenic threat is reaching even the most remote and protected areas such as the Galápagos Archipelago.”
Juan Jose Alava, senior author and principal investigator of the Ocean Pollution Research Unit at Institute for the Oceans and Fisheries at the University of British Columbia, agreed.
“It is imperative that we prioritizing efforts to reduce the input of microplastics into vulnerable ecosystems and food webs, particularly such as that of the endangered Galapagos penguin,” he concluded.