Scramble of results could undermine common method of pollution monitoring
Many scientists using the eggs of wild birds to monitor pollution levels are failing to properly standardize their work, according to a study led by Roland Klein, a biogeographer at Trier University in Germany.
Pollution-monitoring programmes often use birds’ eggs because they are relatively easy to collect and the animals’ positions near the tops of their food chains means that if there are pollutants in the environment birds are likely to take them up. The studies are used to check the levels of pollutants such as flame retardants and mercury from the Arctic to Africa.
Klein and his team went through 86 peer-reviewed papers involving the collection of aquatic birds’ eggs, published between 2002 and 2010, and found that information they view as vital was often missing — including details of sample collection, selection criteria for eggs and how the eggs were transported back to the lab1. All of these factors could influence the results obtained. The team also notes that in general “little attention” has been given to standardizing the collection and storage of eggs across the field.
“There’s high standardization in analysis but poor standardization in collection and sample preservation,” says Klein.
Among the problems identified by the study are that only 45% of papers gave ages for collected eggs, only 41% listed the transport temperature and only 16% provided details of random sampling of nests. All of these factors could undermine the data gleaned from eggs, making comparisons between studies difficult or impossible, Klein says.
Although his team’s work does not quantify the variation that might result from not tackling these issues, Klein says that they do need to be addressed given the huge number of programmes that rely on the monitoring of birds’ eggs. “We spend a lot of money on these things,” he notes.