Blue whale earplug reveals lifetime contaminant exposure and hormone profiles

Abstract

Lifetime contaminant and hormonal profiles have been reconstructed for an individual male blue whale (Balaenoptera musculus, Linnaeus 1758) using the earplug as a natural aging matrix that is also capable of archiving and preserving lipophilic compounds. These unprecedented lifetime profiles (i.e., birth to death) were reconstructed with a 6-mo resolution for a wide range of analytes including cortisol (stress hormone), testosterone (developmental hormone), organic contaminants (e.g., pesticides and flame retardants), and mercury. Cortisol lifetime profiles revealed a doubling of cortisol levels over baseline. Testosterone profiles suggest this male blue whale reached sexual maturity at approximately 10 y of age, which corresponds well with and improves on previous estimates. Early periods of the reconstructed contaminant profiles for pesticides (such as dichlorodiphenyltrichloroethanes and chlordanes), polychlorinated biphenyls, and polybrominated diphenyl ethers demonstrate significant maternal transfer occurred at 0-12 mo. The total lifetime organic contaminant burden measured between the earplug (sum of contaminants in laminae layers) and blubber samples from the same organism were similar. Total mercury profiles revealed reduced maternal transfer and two distinct pulse events compared with organic contaminants. The use of a whale earplug to reconstruct lifetime chemical profiles will allow for a more comprehensive examination of stress, development, and contaminant exposure, as well as improve the assessment of contaminant use/emission, environmental noise, ship traffic, and climate change on these important marine sentinels.cetaceans | cerumen | persistent organic pollutants

Function and evolution of specialized endogenous lipids in toothed whales

“…Wax esters are present in smaller quantities in a variety of species: for example, the wax blooms on the surface of desert insects, where they serve to limit water loss and reflect solar radiation, and in the earwax (9% wax esters) of humans, where it serves to protect the eardrum from debris particles (Hadley, 1985;Bortz et al, 1990;Okuda et al, 1991). Baleen whales have plugs of wax in their ear canals (Trumble et al, 2013), the functions of which are unknown. However, the toothed whales are the only mammals to store large amounts of wax esters within adipose tissues.…”

Multi-year longitudinal profiles of cortisol and corticosterone recovered from baleen of North Atlantic right whales (Eubalaena glacialis)

“…For example, fecal GCs of North Atlantic right whales (Eubalaena glacialis, NARW) show significant increases corresponding with energetically-demanding states such as pregnancy and lactation, as well as with anthropogenic stressors of chronic ocean noise and entanglement Hunt et al, 2006;Rolland et al 2005Rolland et al , 2012. Unfortunately, longitudinal glucocorticoid profiles from individual whales have been extremely difficult to obtain, the best exemplar being one study of GC content of annual cerumen (earwax) layers from a single blue whale (Trumble et al, 2013). Whale earwax plugs, however, are relatively rarely collected, decompose rapidly in stranded specimens, and their temporal resolution appears limited to 6-month periods.…”

From coral reefs to whale teeth: estimating mortality from natural accumulations of skeletal materials

“…In marine mammals, the annual growth rings can additionally be counted on earplugs, which also carry indispensable information on other life history events such as attaining sexual maturity, exposure to contaminants, reconstruction of life-time profiles of hormonal activities (e.g. Ruud & Jonsgård 1950, Ottestad 1950, Trumble et al 2013). The annual regularity of dentine increments still needs validation, though there is a consensus that this method can be applied to some species, taking into account that AD might be underestimated above a particular age (Adams & Watkins 1967, Keay 1996, O'Connor 2000.…”