Establishing growth chronologies from marine mammal teeth: a method applicable across species

摘要: Abstract Multidecadal datasets are important for investigating the effects of a changing climate on top predators, particularly if short-term variations to be differentiated from long-term trends. Annual increments (growth layer groups: GLGs) formed in teeth marine mammals have potential provide multidecadal proxy records or chronologies energy budgets associated with growth, allowing investigation environmental drivers interannual variability and longer-term changes growth. To date, methodology universally applicable across mammal species developing such has not been established. Methodologies developed often “bespoke” being specifically individual datasets. This thereby limits applicability methodologies other regions introduces difficulties replication methods. By modifying dendrochronology (tree-ring dating) techniques, we method GLG widths using sperm whales ( Physeter macrocephalus ) long-finned pilot Globicephala melas as examples. The firstly utilizes statistical crossdating identify correct errors identification ensuring assignment GLGs calendar year. Common “detrending” methods were then tested most appropriate applied remove age-related trends specific each example dataset. Finally, comprised standardized growth index calculated averaged into master chronology dataset, maximizing common patterns individuals reducing noise data due variability. described approach development provides number advantages over others previously used mammals; first, it basis well-established techniques second step-by-step process that is readily repeatable, direct comparisons between similarly different regions. Once developed, can modeling studies compared annually resolved indices explore sensitivities tooth energetic conditions.