An NYT column reports on fur seal whiskers serving as biogeochemical records. This kind of data is more and more common, e.g. otoliths, feathers, shells. What can scientists do with it?
I've mainly seen biogeochemical markers used to infer relatively static traits of individual like origin and age or to make coarse-scale statements about diet (trophic level). The fur seal study got trophic information at a bit finer scale (within-year variation), connecting that to yearly migrations. This is great, but I think really exciting work lies a little further along this path.
Essentially these markers can integrate several years of life for an individual---recording diet and sometimes other environmental features---in some cases they record the entire lifespan. The combination of these integrating markers with tagging data (effectively 'differential' markers) is especially exciting. It would be cool to see cases where hypotheses (models) developed using one type of data were selected using the other type.