Dear Colleagues, We are pleased to announce the publication of two articles on mercury in pinnipeds that will be published in an upcoming issue of Archives of Environmental Contamination and Toxicology. The full text of both articles can be found in the Online First section on the journal website ( http://link.springer.com/journal/244/onlineFirst/page/1). If you do not have access to this journal, please email either Sarah (sarahpeterson23@ gmail.com) or myself (emchuron@ucsc.edu) if you would like a pdf of either article. Peterson SP, McHuron EA, Kennedy SN, Ackerman JT, Rea LD, Castellini JM, O'Hara TM, and Costa DP (2015) Evaluating hair as a predictor of blood mercury: the influence of ontogentic phase and life history in pinnipeds. Arch Environ Contam Toxicol DOI 10.1007/s00244-015-0174-3 *Abstract* Mercury (Hg) biomonitoring of pinnipeds increasingly utilizes nonlethally collected tissues such as hair and blood. The relationship between total Hg concentrations ([THg]) in these tissues is not well understood for marine mammals, but it can be important for interpretation of tissue concentrations with respect to ecotoxicology and biomonitoring. We examined [THg] in blood and hair in multiple age classes of four pinniped species. For each species, we used paired blood and hair samples to quantify the ability of [THg] in hair to predict [THg] in blood at the time of sampling and examined the influence of varying ontogenetic phases and life history of the sampled animals. Overall, we found that the relationship between [THg] in hair and blood was affected by factors including age class, weaning status, growth, and the time difference between hair growth and sample collection. Hair [THg] was moderately to strongly predictive of current blood [THg] for adult female Steller sea lions (*Eumetopias jubatus*), adult female California sea lions (*Zalophus californianus*), and adult harbor seals (*Phoca vitulina*), whereas hair [THg] was poorly predictive or not predictive (different times of year) of blood [THg] for adult northern elephant seals (*Mirounga angustirostris*). Within species, except for very young pups, hair [THg] was a weaker predictor of blood [THg] for prereproductive animals than for adults likely due to growth, variability in foraging behavior, and transitions between ontogenetic phases. Our results indicate that the relationship between hair [THg] and blood [THg] in pinnipeds is variable and that ontogenetic phase and life history should be considered when interpreting [THg] in these tissues. McHuron EA, Peterson SP, Ackerman JT, Melin SR, Harris JD, Costa DP (2015). Effects of age, colony, and sex on mercury concentrations in California sea lions. Arch Environ Contam Toxicol DOI 10.1007/s00244-015-0201-4. *Abstract* We measured total mercury (THg) concentrations in California sea lions (*Zalophus californianus*) and examined how concentrations varied with age class, colony, and sex. Because Hg exposure is primarily via diet, we used nitrogen (*δ*15N) and carbon (*δ*13C) stable isotopes to determine if intraspecific differences in THg concentrations could be explained by feeding ecology. Blood and hair were collected from 21 adult females and 57 juveniles from three colonies in central and southern California (San Nicolas, San Miguel, and Año Nuevo Islands). Total Hg concentrations ranged from 0.01 to 0.31 μg g-1 wet weight (ww) in blood and 0.74 to 21.00 μg g-1 dry weight (dw) in hair. Adult females had greater mean THg concentrations than juveniles in blood (0.15 vs. 0.03 μg g-1ww) and hair (10.10 vs 3.25 μg g-1 dw). Age class differences in THg concentrations did not appear to be driven by trophic level or habitat type because there were no differences in *δ*15N or *δ*13C values between adults and juveniles. Total Hg concentrations in adult females were 54% (blood) and 24% (hair) greater in females from San Miguel than San Nicolas Island, which may have been because sea lions from the two islands foraged in different areas. For juveniles, we detected some differences in THg concentrations with colony and sex, although these were likely due to sampling effects and not ecological differences. Overall, THg concentrations in California sea lions were within the range documented for other marine mammals and were generally below toxicity benchmarks for fish-eating wildlife. Best Regards, Liz McHuron and Sarah Peterson -- Elizabeth McHuron, PhD Student Ecology & Evolutionary Biology Center for Ocean Health, Long Marine Lab 100 Shaffer Rd. University of California Santa Cruz, CA 95060 emchuron@ucsc.edu