The three aspects of egg orientation (roll, pitch, and yaw) in a single Forster’s tern egg. White areas indicate daytime, while gray areas indicate nighttime.

<p>The red line represents roll, the black line indicates pitch, and the green line indicates yaw. Note the large change in yaw angle relative to roll and pitch, as well as the difference in egg turning activity between night and day.</p

Mercury Exposure May Suppress Baseline Corticosterone Levels in Juvenile Birds

Mercury exposure has been associated with a wide variety of negative reproductive responses in birds, however few studies have examined the potential for chick impairment via the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis regulates corticosterone levels during periods of stress. We examined the relationship between baseline fecal corticosterone metabolite concentrations and mercury concentrations in down feathers of recently hatched (<3 days) and blood of older (15–37 days) Forster’s tern (<i>Sterna forsteri</i>) chicks in San Francisco Bay, California. Baseline fecal corticosterone metabolite concentrations were negatively correlated with mercury concentrations in blood of older chicks (decreasing by 81% across the range of observed mercury concentrations) while accounting for positive correlations between corticosterone concentrations and number of fledgling chicks within the colony and chick age. In recently hatched chicks, baseline fecal corticosterone metabolite concentrations were weakly negatively correlated with mercury concentrations in down feathers (decreasing by 45% across the range of observed mercury concentrations) while accounting for stronger positive correlations between corticosterone concentrations and colony nest abundance and date. These results indicate that chronic mercury exposure may suppress baseline corticosterone concentrations in tern chicks and suggests that a juvenile bird’s ability to respond to stress may be reduced via the downregulation of the HPA axis

The hourly number of turns and egg temperature during the night and during the day in terns.

<p>(A) Hourly number of turns. (B) Egg temperature. The boxes denote the median, 25 & 75% quartiles, the range of data, and outliers.</p

Five days of egg temperature and egg turn rate from a single tern nest.

<p>The blue line represents egg temperature, and the orange bars represent the number of egg turns in each hour. White areas indicate daytime, while gray areas indicate nighttime.</p

Statistical results of the three multiple regressions models.

<p>Statistical results of the three multiple regressions models.</p

Foraging behavior of northern elephant seals and mercury concentrations in blood and muscle

We quantified variables for the full foraging trip (short and long foraging trip) to describe foraging behavior of northern elephant seals, using geography, diving behavior, and stable isotopes (carbon and nitrogen). Most seals were weighed upon recovery. If not, then RecoveryMassEstimated was recorded as 1, meaning that the recovery mass was estimated using body composition and morphometric measurements. The ToppID is the unique ID for the individual and the foraging trip that would link with the full diving and tracking file, housed at the University of California, Santa Cruz. The Seal_ID is an ID that corresponds to each seal in this study and links with their individual histories, also housed at the University of California, Santa Cruz

Mercury Bioaccumulation in Estuarine Fishes: Novel Insights from Sulfur Stable Isotopes

Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the San Francisco Bay Estuary. We employed a tiered approach that first examined processes influencing variation in fish THg among wetlands, and subsequently examined the roles of habitat and within-wetland processes in generating larger-scale patterns in fish THg. We found that δ³⁴S, an indicator of sulfate reduction and habitat specific-foraging, was correlated with fish THg at all three spatial scales. Over the observed ranges of δ³⁴S, THg concentrations in fish increased by up to 860% within wetlands, 560% among wetlands, and 291% within specific impounded wetland habitats. In contrast, δ¹³C and δ¹⁵N were not correlated with THg among wetlands and were only important in low salinity impounded wetlands, possibly reflecting more diverse food webs in this habitat. Together, our results highlight the key roles of sulfur biogeochemistry and ecology in influencing estuarine fish THg, as well as the importance of fish ecology and habitat in modulating the relationships between biogeochemical processes and Hg bioaccumulation

Mercury concentrations in foraging and fasting seals

These are the supporting data for Peterson et al. 2018 “Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal.” Included is the ID of each individual seal, the sex of each seal, and the date of the sample collection. We indicate which samples we used in each paired analysis (blood, muscle, and hair analyses across foraging trips or fasting periods). We indicate the Foraging Trip (Post-breeding vs. Post-molting) or Fasting Period (Breeding vs. Molting) that was used in analyses as well as the time period within a foraging trip (Pre-foraging vs. Post-foraging) or fasting period (Early fasting vs. Late fasting). We provide the mass (kg) of adult female seals and the standard length (cm) of seals. Total mercury (THg) concentrations are presented for blood (wet weight), hair (dry weight), and muscle (dry weight) in micrograms THg per gram (ppm). Note that individual seals are sampled multiple times in this dataset, thus the sampling dates are important to align samples temporally. Please contact the authors before using these data

Supplementary summary tables and figures for Peterson et al. 2018 from Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal

Supplementary summary tables and figures for Peterson et al. 2018 “Foraging and fasting can influence contaminant concentrations in animals: an example with mercury contamination in a free-ranging marine mammal.” ESM Table 1 provides the sample sizes and summary total mercury (THg) concentrations for adult female and male northern elephant seals (Mirounga angustirostris). ESM Table 2 provides a summary of the change in THg concentrations and the percent change in THg concentrations across fasting and foraging periods. ESM Figure 1 shows one year in the life of an adult female northern elephant seal with the direction of observed changes in tissue THg across specific life history events. ESM Figure 2 shows the changes in male tissue THg concentrations across life history events. ESM Figure 3 shows the proportional change in tissue THg concentrations across life history events in relation to the tissue THg concentrations at the start of the fasting or foraging period

Location of study at Agattu Island in the Aleutian Archipelago, Alaska.

<p>Outline of Agattu Mountains is indicated by 300</p