ISOTOPIC ANALYSIS OF CORONULID BARNACLE SHELLS TO RECONSTRUCT MYSTICETE WHALE MIGRATION

Modern mysticete whales migrate thousands of miles each year to reach the seasonally productive waters on which they rely. Migration is a critically important aspect of mysticete ecology and natural history, yet relatively little is known about migratory pathways in the prehistoric past. The fossil record of coronulids – the epizoic barnacles that attach to many mysticetes – offers a potential proxy for reconstructing prehistoric migration routes. The isotopic composition of each growth increment of a coronulid shell depends on the temperature and isotopic makeup of the seawater in which it was formed, and thus a barnacle attached to a migrating whale may preserve a high-resolution geochemical record of the whale’s annual migration path (Killingley, 1980). Coronulid genera now closely associated with specific mysticete genera are found in the Pliocene–recent fossil record, offering the possibility of assessing the stability of migration patterns over geological timescales. Here we present initial results from an ongoing investigation of modern and fossil coronulids. Oxygen isotope profiles of Coronula diadema specimens collected from a beached humpback whale are consistent with the whale having migrated along the common route of the population to which it belonged, suggesting that the fossil record of coronulids offers a promising new window into the ecological history of mysticete whales.