Assessing Fukushima-Derived Radiocesium in Migratory Pacific Predators.

The 2011 release of Fukushima-derived radionuclides into the Pacific Ocean made migratory sharks, teleosts, and marine mammals a source of speculation and anxiety regarding radiocesium (134+137Cs) contamination, despite a lack of actual radiocesium measurements for these taxa. We measured radiocesium in a diverse suite of large predators from the North Pacific Ocean and report no detectable (i.e., ≥ 0.1 Bq kg-1 dry wt) Fukushima-derived 134Cs in all samples, except in one olive ridley sea turtle (Lepidochelys olivacea) with trace levels (0.1 Bq kg-1). Levels of 137Cs varied within and across taxa, but were generally consistent with pre-Fukushima levels and were lower than naturally occurring 40K by one to one to two orders of magnitude. Predator size had a weaker effect on 137Cs and 40K levels than tissue lipid content. Predator stable isotope values (δ13C and δ15N) were used to infer recent migration patterns, and showed that predators in the central, eastern, and western Pacific should not be assumed to accumulate detectable levels of radiocesium a priori. Nondetection of 134Cs and low levels of 137Cs in diverse marine megafauna far from Fukushima confirms negligible increases in radiocesium, with levels comparable to those prior to the release from Fukushima. Reported levels can inform recently developed models of cesium transport and bioaccumulation in marine species.

Blue whale earplug reveals lifetime contaminant exposure and hormone profiles.

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.

Salmonella Newport omphaloarteritis in a stranded killer whale (Orcinus orca) neonate.

Salmonella enterica serovar Newport (Salmonella Newport) was isolated from multiple tissues in a neonate killer whale (Orcinus orca) that stranded dead in 2005 along the central coast of California, USA. Necrotizing omphaloarteritis and omphalophlebitis was observed on histologic examination suggesting umbilical infection was the route of entry. Genetic analysis of skin samples indicated that the neonate had an offshore haplotype. Salmonellosis has rarely been identified in free-ranging marine mammals and the significance of Salmonella Newport infection to the health of free-ranging killer whales is currently unknown.

Seasonal differences in biochemical adaptation to fasting in juvenile and subadult Steller sea lions (Eumetopias jubatus).

Nine Steller sea lions (Eumetopias jubatus) aged 1.75-6 yr were experimentally fasted for 7-14 d during the breeding and nonbreeding seasons to identify changes in plasma metabolites that are indicative of fasting and to determine whether the ability of sea lions to fast varies seasonally or with age. Although some animals approached the limit of their protein-sparing ability by the end of our fasting experiments, there was no sign of irreversible starvation biochemistry. Plasma blood urea nitrogen (BUN) concentrations decreased in all animals within the first week of fasting, reflecting a shift to a fasting-adapted state; however, significant increases in plasma BUN concentration at the end of the nonbreeding season fasts suggest that subadult Steller sea lions were not able to maintain a protein-sparing metabolism for a full 14 d during the nonbreeding season. In contrast, juveniles were able to enter protein sparing sooner during the nonbreeding season when they had slightly higher initial percent total body lipid stores than during the breeding season. Subadult and juvenile sea lions had low circulating ketone body concentrations compared with young sea lion pups, suggesting an age-related difference in how body reserves are utilized during fasting or how the resulting metabolites are circulated and catabolized. Our data suggest that metabolite concentrations from a single blood sample cannot be used to accurately predict the duration of fast; however, threshold metabolite concentrations may still be useful for assessing whether periods of fasting in the wild are unusually long compared with those normally experienced.