SemOpenAlex |

SemOpenAlex

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2938254257> ?p ?o ?g. }

Showing items 1 to 100 of ±120 with 100 items per page.

W2938254257 endingPage "1642" @default.
W2938254257 startingPage "1625" @default.
W2938254257 abstract "Arctic ecosystems are experiencing rapid environmental changes (e.g., reduction in sea-ice extent, rising temperatures) coupled with the effects of increasing human activity associated with resource extraction, vessel traffic, and commercial fishing (Pompa et al. 2011, Doney et al. 2012, Moore et al. 2012). As a result, anthropogenic impacts on Arctic wildlife such as bowhead whales (Balaena mysticetus) are expected to escalate (Reeves et al. 2012). Assessing stress responses in marine wildlife by quantifying adrenal steroid hormones (i.e., glucocorticoids; cortisol, corticosterone, and/or their metabolites) has been a valuable tool for evaluating the physiological impacts of anthropogenic disturbance (Ayres et al. 2012; Rolland et al. 2012, 2017; Atkinson et al. 2015; Kellar et al. 2015), and for monitoring the impacts of ecological changes (Romero and Wikelski 2001, Bechshøft et al. 2012). Glucocorticoid hormones (GCs) have been analyzed in several sample types in marine mammals, including blood (i.e., serum, plasma), blubber, feces, hair, saliva, exhaled respiratory vapor (“blow”), cerumen (i.e., earwax, ear plug), and baleen (e.g., Hogg et al. 2005, 2009; Amaral 2010; Rolland et al. 2012, 2017; St. Aubin et al. 2013; Trumble et al. 2013; Hunt et al. 2014; Kellar et al. 2015; Champagne et al. 2016; Robeck et al. 2017; Burgess et al. 2018). The temporal signature of the physiological response manifested as concentrations of GCs in these different types of biological samples varies from real-time (blood) or near real-time (blow), to hours or days (blubber, feces) or months to years (cerumen, hair, and baleen). Experimental design and data interpretation should consider the temporal dynamics of the hormones accumulated or sequestered in different sample types. Thus, concentrations of stress hormones in blood and blow reflect acute stress responses, while those measured in feces, blubber, baleen, cerumen, and hair indicate chronic or repeated hypothalamic-pituitary-adrenal (HPA) axis activity (Dickens and Romero 2013, Dantzer et al. 2014, Rolland and Moore 2018). In this study, we analyzed GC hormones in baleen from a western Arctic bowhead whale that endured a severe, prolonged entanglement in fishing gear to investigate whether a chronic stress response from the entanglement could be detected. Analysis of steroid hormones in baleen is uniquely valuable in that a retrospective longitudinal record of hormone concentrations over many years can be documented on a single plate (depending on the species and length of the plate) with at least monthly resolution (Hunt et al. 2014). Baleen is a keratinous, integumentary tissue similar in structure to hair, nails, and feathers. These tissues grow continuously throughout life, and steroid hormones have been quantified in all of these matrices using immunoassay techniques (e.g., Davenport et al. 2006, Bortolotti et al. 2008, Bechshøft et al. 2011, Hunt et al. 2014, Izawa et al. 2015). Researchers have hypothesized that hormones are incorporated into these integumentary tissues by passive diffusion from capillaries feeding the highly vascularized follicles from which they grow (Meyer and Novak 2012). Thus, the hormone content of a baleen sample from a given location along the plate reflects an integrative measure of the circulating levels of that hormone during the period of tissue growth. Studies have shown that hormone concentrations in keratinized tissues increase during prolonged or repeated elevation of circulating levels, but not in response to single, acute hormone elevations (Endo et al. 2017, Tallo-Parra et al. 2017). Therefore, GC concentrations in these integumentary tissues are being explored as a method for assessing a record of chronic stress responses (Meyer and Novak 2012, Mack and Fokidis 2017). In bowhead whales, we previously validated immunoassays for progesterone and cortisol (i.e., immunoreactive hormones and/or their metabolites) in baleen, and found that levels of both hormones varied according to sex, maturity, and pregnancy status (Hunt et al. 2014). In the current study, we validated an immunoassay system in bowhead baleen for an additional adrenal cortical hormone, corticosterone. Increased GCs in baleen in response to both anthropogenic and natural stressors have been reported recently in right whales (Eubalaena sp.). Lysiak et al. (2018) found elevated corticosterone in a baleen plate from a North Atlantic right whale (E. glacialis) with a chronic fishing gear entanglement that was eventually fatal. Fernández Ajó et al. (2018) attributed postnatal increases in baleen GCs to chronic stress from repeated wounding by kelp gulls (Larus dominicanus) in two southern right whale calves (E. australis). Variation in baleen GCs associated with energetically demanding life history stages such as pregnancy and lactation has been reported in E. glacialis (Hunt et al. 2017a). Additional steroid and thyroid hormones have also been extracted and quantified in baleen from mysticete whales (Hunt et al. 2017b), potentially expanding insights into reproductive physiology, metabolic activity, and nutritional status. Here, we analyzed baleen samples for both GC hormones (i.e., immunoreactive cortisol and corticosterone and/or their metabolites) along the length of a baleen plate from an 11.1 m juvenile male bowhead whale that was severely entangled in fishing rope when it died. For comparison, we present data on the same adrenal hormones measured in baleen samples from seven apparently healthy, male bowhead whales as a nonentangled reference group. The objectives of this study were to (1) determine whether we could detect an increase in GCs in baleen that might reflect sustained activation of the HPA axis related to the entanglement; (2) investigate the approximate timeframe of the entanglement event based on the location on the plate of the initial elevation of GCs above baseline concentrations for the whale, and estimated baleen growth rates; (3) assess the relative variation in cortisol and corticosterone in baleen in response to chronic stress from entanglement; (4) compare baleen GC concentrations in the entangled whale to those of nonentangled male bowheads; and (5) evaluate GC concentrations in a second sample type, feces, collected shortly after death during a time when the whale was known to be severely entangled. The entangled bowhead whale (17B6) was hunted for subsistence on 5 May 2017 by Inupiaq hunters from Utqiaġvik (Barrow), Alaska, under a quota approved by the International Whaling Commission. The captain and crew described the whale as lethargic (“resting at the surface”) as they approached it by boat, and they noted a rope trailing from the whale. They assumed it was a whale that may have been struck earlier, but lost. The hunters killed the whale instantly with a penthrite projectile that struck the cervical vertebrae. The whale was towed and hoisted (or “landed”) onto shorefast sea ice, where a severe, multicontact rope entanglement became apparent; the hunters estimated that 100–200 m of 19 mm diameter rope was attached to the whale. The rope was tightly anchored to the baleen rack, wrapped once around the left pectoral flipper, and wrapped tightly six times around the peduncle, penetrating ∼10 cm through the epidermis into the underlying blubber tissue (Fig. 1). (Note that the rope was briefly used as a towline, but not to hoist the whale onto the ice, nevertheless some penetration into subsurface tissues may have partially been a handling artifact.) The rope was cut off the whale by the hunters during harvest, and fraying of the rope ends was consistent with cut ends that had not been heat sealed or whipped (Fig. 2). It could not be determined from the available evidence whether the fishing gear was in active use when the whale became entangled. The rope removed from the whale measured 84.02 m in length and weighed 17.27 kg, although not all of the rope was retrieved or available for examination, so these are minimum measurements. There appeared to be two different types of rope including a white rope that was probably nylon and a blue flecked rope that was likely a copolymer fishing line (Fig. 2). Growth of algae and some marine worms on the rope suggested either prolonged fishing gear deployment or chronic entanglement. The gear was not marked; therefore, the specific fishery of origin was unknown, although rope characteristics (type, diameter and length) were consistent with Bering Sea fixed-gear pot fisheries (e.g., crab and cod). Pathological findings included an open traverse laceration (∼35 cm long) in the posterior body of the tongue. This lesion extended into the underlying muscle and the wound bed appeared somewhat necrotic (“pus” was noted). Histopathological results for the glossal rope injury were characterized by myofiber degeneration (multifocal, mild with stromal edema), and mucosal epithelial hyperplasia (diffuse, moderate with stromal fibrosis and lymphoplasmacytic glossitis). About 50% of the white chin patch was discolored yellow likely due to colonization by diatoms or algae. Incidental findings included a nuclear cataract (left eye) that obscured about 50% of the field of vision (RS, unpublished data). The right eye was not collected. Body condition appeared poor to hunters and observers based on a thin body shape, especially in the posterior region (see Fig. 1A). This observation was supported by the umbilical girth measurement (594 cm), which was the smallest measured for bowheads of this body length (11.0–11.2 m length, n = 9, umbilical girth (mean ± SD) = 676.9 ± 71.5 cm). Although the axillary girth (730 cm) was typical for a whale of this size there was some doubt about the accuracy of this measurement, and Miller et al. (2012) found that the umbilical area (i.e., 60% of the body length from the snout) showed the largest variation in width with body condition changes in closely related Eubalaena sp. Additionally, while blubber thickness (19 cm ventral, 23 cm dorsal) was considered normal for a whale in this age-class, the hypodermis was thin (1–2 cm; North Slope Borough, unpublished data), and George et al. (2015) showed that blubber thickness scaled with body length, not body condition (or presumably lipid percentage) and Rosa (2006) noted large variation in the percent lipid in bowhead blubber. While it is possible that the whale was able to feed while entangled, foraging efficiency would have been compromised by the damage to the tongue and baleen. Further, van der Hoop et al. (2016) showed that severely entangled right whales (Eubalaena glacialis) experience greatly increased energetic expenditures from the drag created by carrying fishing gear, which would have accelerated the loss of body condition in this whale. Gross examination results including extensive scar tissue formation associated with the rope embedded around the peduncle, algal growth and marine worms on the fishing lines, and the poor body condition of the whale were all evidence of a chronic entanglement of unknown duration. The opinion of the hunters and attending biologists was that the entangled whale was severely compromised physically, there was a low probability that the rope would have been shed, and had it not been harvested, the whale would not have survived. A single 227 cm long baleen plate was extracted from the rostrum, gum tissue (mammaq) was manually scraped off the base (closest to the maxilla), and the plate was stored at ambient temperatures in Utqiaġvik until shipment to the New England Aquarium Laboratory (Boston, MA). Prior to sampling, the plate was wiped clean of any surface contaminants using 100% ethanol. A measuring tape was fixed to the labial margin to guide accurate sample collection intervals along the plate (Fig. 3). Samples of pulverized baleen powder were obtained using a hand-held electric Dremel rotary tool (Model 3000 Variable Speed) fitted with a tungsten carbide cutter tip (model 9901). Pulverized baleen powder was collected by drilling full thickness through the plate (∼0.5 cm wide) across the transverse growth lines down the midline of the plate (Fig. 3). The Dremel tool, tip, and baleen were cleaned thoroughly with ethanol between sampling locations to prevent cross-contamination. Sample collection intervals were designed to maximize the possibility of capturing data on the entanglement event from more recent baleen growth, and to establish baseline levels of GCs prior to the presumed start of the entanglement using samples of the older (more distal) end of the baleen. Baleen grows faster in younger whales, reaching an asymptote in adult bowheads (Lubetkin et al. 2008, George et al. 2016). Without a method such as stable isotope analysis to establish a specific timeline for the sampling locations on the plate, an estimated baleen growth rate was used for this study which is likely underestimated, especially for the oldest samples (when the whale was younger and the baleen growth rate was faster). Because our priority was the timeline for the most recent samples during the entanglement, we based the sampling intervals on an estimated 17.5 cm/yr of baleen growth for adult bowhead whales (Lubetkin et al. 2008), since this whale was close to sexual maturity based on body length (12–13 m; Koski et al. 1993, O'Hara et al. 2002). Starting at the plate base, samples were collected every 1.25 cm for the first 35 cm, and then every 2.5 cm for the remainder of the plate up to 202.5 cm (the tip of the plate was too thin to drill sufficient baleen powder for analysis). Based on the estimated baleen growth rate, for the first 35 cm of the plate (∼2 yr of growth) each data point represented approximately 26 d, whereas later points at the wider sampling interval represented ∼52 d. These parameters were used to estimate the timeframe of a physiological response by the whale in response to the entanglement. A total of 96 samples were drilled from 17B6's plate for analysis, spanning the month of harvest (May 2017) retrospectively through approximately November 2005. For each sample, 0.1 ± 0.01 g of baleen powder was weighed into 16 × 100 mm borosilicate glass test tubes and extracted with 4.0 mL of 70% ethanol. Samples were vortexed for 2 h before centrifuging for 15 min (4,000 × g) to separate the baleen pellet from the supernatant. Next, 3.0 mL of supernatant was pipetted into a clean tube and evaporated completely under compressed airflow and heat (45°C). The dried sample was reconstituted in 0.5 mL of buffer (Arbor Assays #X065) and vortexed briefly to reconstitute and homogenize the hormone extract before decanting into a cryovial. Following overnight storage (−20°C), extracts were thawed, spun in a mini-centrifuge to form a pellet from any remaining baleen particulates, and the supernatant was decanted into a clean cryovial and stored at −20°C until hormone assay. Glucocorticoids were measured using DetectX Cortisol (#X003) and DetectX Corticosterone (#X014) enzyme immunoassay (EIA) kits (Arbor Assays, Ann Arbor, MI). Validation tests for the DetectX Cortisol EIA for bowhead baleen samples were previously performed by our laboratory (see Hunt et al. 2014). Standard assay validation tests (parallelism and accuracy) were performed for the corticosterone EIA to ensure that the assay system could reliably detect and measure corticosterone in bowhead whale baleen samples. Parallelism was assessed on pooled sample extracts of both recent baleen growth (5 cm from the plate base) and older growth (95 cm from the base). These two locations were tested to ensure that hormones deposited in baleen plates exhibited similar antibody binding regardless of more prolonged exposure to seawater in the older samples. Baleen extracts were serially diluted (1:1 [neat, no dilution] up to 1:128). Results were graphed as percent-bound (y-axis) vs. relative hormone dose (x-axis). An F-test was used to confirm that the slope of the linear portion of the serial-dilution curve was not different from the standard curve (i.e., parallel slopes). Assay accuracy was assessed by spiking a duplicate standard curve with an equal volume of pooled baleen extract at 1:1 (neat). Results were graphed as observed vs. expected standard concentration, and linearity and slope were assessed. The corticosterone EIA demonstrated good parallelism and accuracy for bowhead baleen extracts. For the parallelism tests, both the new and old extract pools showed relatively low, but detectable corticosterone. The slope of the serially-diluted extracts was not significantly different from the standard curve for new (F1,8 = 0.23; P = 0.64) or old (F1,8 = 3.24; P = 0.19) growth baleen, indicating the assay system could reliably detect the hormone of interest in both recent growth and older baleen samples. Good parallelism indicates that the assay antibody reliably binds to an immunoreactive component in the sample with an affinity that is similar to the target hormone. Accuracy test results showed that the slope of the observed vs. expected concentration graph was 0.8363 with an r2 = 0.9958. This falls within the accepted slope range of 0.8–1.2, indicating that there were no substances within the baleen extract matrix interfering with accurate measurement of immunoreactive corticosterone in this assay system. Based on validation results, baleen samples were assayed neat (1:1) following the manufacturer's protocol—except for the cortisol assay, where assay buffer #X065 was substituted for use (instead of the #X053 buffer included with the kit). All samples were analyzed in duplicate, low and high hormone dose controls were assayed in tandem, and zero dose (blanks) and nonspecific binding wells were run on all plates to ensure consistency across the data set. Samples exceeding 10% coefficient of variation (CV) between duplicates were reassayed. Interassay CVs for control samples were 9.1% (low) and 5.0% (high) for cortisol (n = 9 assays); and 8.2% (low) and 3.5% (high) for corticosterone (n = 14 assays). Hunt et al. (2017b, table 2) gives the details of antibody cross-reactivity for both assays. Final hormone results are presented as nanograms of immunoreactive hormone per gram of baleen powder (ng/g). Baseline concentrations for immunoreactive cortisol and corticosterone in baleen from whale 17B6 were calculated from the preentanglement hormone data (ca. 2005–2015) using an iterative process that excluded all data points greater than the mean+2SD until no points exceeded this maximum value (following Lysiak et al. 2018). Glucocorticoids were considered elevated if they were above this baseline concentration +2SD. Standard descriptive statistics were also calculated (mean ± SD) for the pre-entanglement data interval. The relationship between the two GCs in baleen from 17B6 was analyzed using Pearson's correlation coefficient and log10 transformed data (due to nonnormal data distributions based on skewness and kurtosis). Data analyses were performed using SPSS Statistical Software (version 25.0; IBM Corp., Armonk, NY). For all analyses, P < 0.05 was considered significant. Additionally, a fecal sample was collected from the colon of 17B6 at harvest and stored frozen (−20°C) until hormone analysis. In contrast to the multisample longitudinal hormone record laid down in baleen, this fecal sample represented an integrative measure of recent average concentrations of circulating GCs (approximately 1–2 d prior to harvest based on estimated gut transit time for balaenid whales; Rolland et al. 2005). The sample was freeze-dried (∼7 d), and GC metabolites were extracted with 90% methanol using methods similar to those published for North Atlantic right whales (Hunt et al. 2006). The sample was diluted 1:80 in the radioimmunoassay (RIA) buffer (steroid diluent #07199196, MP Biomedicals, Costa Mesa, CA) for analysis, and GC concentrations were measured using a 125I double-antibody corticosterone RIA kit (#07-120102; MP Biomedicals), which was previously validated for bowhead whale feces (RMR, unpublished data). Results are presented as ng of immunoreactive hormone metabolites per gram of dried feces (ng/g). The concentration of fecal corticosterone in this whale at harvest was compared to mean concentrations for bowhead whales of this sex and age-class determined in previous work (RMR, unpublished data). Baleen plates from the reference group of male bowheads (n = 7) were collected during subsistence harvests in Utqiaġvik and Gambell, Alaska, between 2006 and 2012. This cohort included three subadult males (one juvenile and two pubertal), and four adult males based on body length (Koski et al. 1993, O'Hara et al. 2002). This reference GC data set was compiled from archived baleen powder taken at ∼2.5 cm intervals along the plate of each male, using the same sampling method described above for 17B6. Pulverized baleen samples from consecutive sampling sites were combined to achieve adequate mass for analysis to delineate either biannual or annual values, depending on the available sample weight. A total of 127 samples were analyzed from the reference group, with individual whales contributing between 10 and 37 baleen samples. Baleen cortisol and corticosterone concentrations in these samples were assayed concurrently using the same methods described for whale 17B6. The mean, SD, baseline (calculated using the methods described above), and maximum cortisol and corticosterone concentrations were determined for the subadult and adult males (as two separate groups) to compare with baleen GC concentrations in whale 17B6. Glucocorticoid concentrations along the entire length of 17B6's baleen plate ranged from 0.01 ng/g to 3.23 ng/g for cortisol and from 0.17 ng/g to 1.14 ng/g for corticosterone. Cortisol and corticosterone were positively correlated, showing similar trends (two-tailed Pearson's correlation coefficient, r = 0.614, P < 0.01, n = 96). Concentrations of both GCs were <1.0 ng/g with little variability for approximately a decade before the presumed entanglement event, and corticosterone was consistently present at higher levels than cortisol during this interval (Fig. 4). Mean hormone concentrations (± SD) during this preentanglement period (∼2000–2015), were 0.15 ± 0.06 ng/g for cortisol and 0.53 ± 0.17 ng/g for corticosterone, and these were also the baseline concentrations since there were no outlier values (Table 1). The baseline cortisol and corticosterone concentrations in 17B6 were lower than the baselines (± SD) in the healthy male subadults (cortisol = 0.49 ± 0.12 ng/g; corticosterone = 1.02 ± 0.25 ng/g) and adults (0.32 ± 0.04 ng/g; 0.74 ± 0.13 ng/g; Table 1). Baleen cortisol concentrations in 17B6 first exceeded the cutoff level (baseline + 2SD) at 11.25 cm from the plate base (∼September 2016), with a slightly increased concentration (0.31 ng/g). Cortisol was chronically elevated (at least double baseline) for approximately 6 mo (starting approximately October 2016), and increased dramatically to the maximum level detected (3.23 ng/g) about 1 mo prior to death (Fig. 4). Cortisol started to decline in the most recent sample of baleen (although still highly elevated at 2.09 ng/g), possibly due to the severely debilitated physical state of the whale. The peak cortisol concentration was over 20-fold higher than the preentanglement baseline in this whale, clearly showing a significant adrenal stress response was recorded in baleen. Peak cortisol levels in 17B6 were 6–10 fold higher compared to the nonentangled male baselines, and double the maximum value (1.6 ng/g) found in these reference whales. In 17B6, baleen corticosterone showed a much less pronounced response to the entanglement compared to cortisol. Corticosterone concentration was first elevated several months later than cortisol (∼January 2017), and remained above the baseline + 2SD throughout the most recent baleen samples (Fig. 4). The maximum corticosterone level (1.14 ng/g) was only about 2-fold higher than this whale's baseline concentration. It was only slightly higher than the baselines for the reference group of subadults (Table 1; 1.02 ± 0.25 ng/g) and adults (0.74 ± 0.13 ng/g), and was exceeded by the maximum concentration seen in two healthy subadults (1.90, 2.70 ng/g) and two adults (1.23, 1.67 ng/g). Higher concentrations of both GCs in the most recent baleen samples from the two pubertal males influenced hormone concentrations in the subadult male reference group. This increase in GC levels was likely related to enhanced steroidogenesis associated with the onset of sexual maturation. Because 17B6 was a juvenile whale with immature gonads, the increased baleen GCs in this whale were not related to reproductive maturity, persisted for 4–6 mo, and for cortisol, greatly exceeded both this whale's baseline and the reference group's baseline concentrations. Fecal GCs in 17B6 were 370.93 ng/g, which is over five-fold higher than reference levels for subadult male bowhead whales (mean ± SE: 66 ± 12 ng/g, n = 22; RMR, unpublished data), confirming the extreme stress response present in this whale in the days before harvest (Rolland et al. 2005). In addition, blood analysis indicated a leucocyte profile consistent with chronic stress in vertebrates (low white blood cell count; low lymphocyte count; Atkinson et al. 2015). Results of this study support the conclusion that chronic adrenal gland activation caused by a severe fishing rope entanglement was recorded in the baleen from this bowhead whale. Significantly elevated baleen GCs were also reported in a North Atlantic right whale that was fatally entangled in fishing gear (Lysiak et al. 2018). Studies in other taxa have also documented chronic adrenal gland activation recorded in hair and other keratinized tissues (D'Anna-Hernandez et al. 2011, Bryan et al. 2013, Mack and Fokidis 2017). Recent research using ACTH stimulation to mimic HPA axis activation in goats and calves showed that acute fluctuations in circulating GCs were not reflected in hair—the authors concluded that elevated hair GCs likely resulted from longer term activation of the HPA axis (Endo et al. 2017, Tallo-Parra et al. 2017). These studies from other taxa provide further evidence that the elevation of GCs over multiple months found in baleen from 17B6 reflected an adrenal response to the chronic entanglement experienced by this whale. In addition, marked increases in fecal GCs at harvest confirmed an enhanced stress response in this whale using a second sample matrix. The fecal corticosterone level was consistent with the range of fecal GC concentrations reported for chronically entangled North Atlantic right whales (Rolland et al. 2017). Entanglements in this right whale population have been well documented, and persist from months to years (mean of 6 mo), resulting in severe physical trauma, highly elevated stress hormones, poor body condition, reduced reproduction and often a prolonged health decline prior to death (Cassoff et al. 2011; Schick et al. 2013; Rolland et al. 2016, 2017). Bycatch in fishing gear is among the most significant anthropogenic threats to large whales globally (Cassoff et al. 2011, Knowlton et al. 2012, Reeves et al. 2013). Although not yet a major conservation threat for the Bering-Chukchi-Beaufort Seas (BCBS) population of bowheads, about 50% of adult bowhead whales in the western Arctic showed evidence of fishing gear entanglement based upon the presence of characteristic scars (George et al. 2017). Commercial fishing effort has expanded northward with diminishing ice cover leading to an increased risk of encountering fishing gear for bowhead whales and other marine mammals. Given the variability of baleen growth rates (especially in younger whales), and several months difference in the responses of the two GCs, the date when 17B6 became entangled cannot be precisely determined, but the hormone data suggest that it occurred sometime between autumn 2016 and early winter of 2017. This approximate timeframe is consistent with the southward migration of BCBS bowhead whales from summer feeding habitats in the Beaufort and Chukchi Seas to the northern Bering Sea in autumn where there is extensive commercial fishing activity. Analysis of stable isotopes in parallel with hormone analysis in future work could further refine the timeline, and, therefore, the presumed location of this entanglement (Lysiak et al. 2018). Immunoreactive cortisol and corticosterone were both measurable in baleen from 17B6, and baseline corticosterone concentrations were over 3-fold higher than baseline cortisol. This is consistent with other recent studies of GCs in baleen, in which corticosterone concentrations were up to 4-fold higher than cortisol in baleen (Hunt et al. 2017a, 2018; Lysiak et al. 2018). Although the specific mechanisms for deposition of circulating GCs into baleen have not been determined, the different physicochemical properties of the two glucocorticoids undoubtedly affects both accumulation and retention of the two GCs in the baleen matrix. For example, the partition coefficient for corticosterone is almost double that of cortisol for crossing the blood-brain barrier in rats, and is related to the lipid solubility of the compounds and the tendency to form hydrogen bonds with water (Partridge and Mietus 1979). Therefore, baseline concentration of corticosterone within baleen may be increased relative to cortisol due to its greater lipophilicity or other properties that enhance its retention within the baleen matrix. In addition, the potential effects of structural alteration of GCs deposited in baleen are unknown (if this occurs), as is the possible influence of local hormone production, as reported for GCs measured in hair follicles (Keckeis et al. 2012). Although both GCs exceeded baseline values in 17B6 for multiple months presumably due to the entanglement in the current study, the response by cortisol occurred earlier and was much more pronounced compared to corticosterone. Cortisol is believed to be the predominant form of circulating GC in cetaceans (“cortisol-dominant”; Ortiz and Worthy 2000, Atkinson et al. 2015, O'Brien et al. 2017), and the results of the current study indicate a primary role for cortisol in the adrenal response to this chronic entanglement. Serum GCs from a physically debilitated, live-stranded North Atlantic right whale had much higher concentrations of cortisol compared to corticosterone, suggesting that a cortisol response was also predominant in this highly stressed right whale (Rolland et al. 2017). However, Lysiak et al. (2018) found that baleen corticosterone concentrations were highest, and cortisol levels were actually lower than the baseline during a chronic entanglement in an adult female North Atlantic right whale. Hunt et al. (2018) suggested that both GCs were increased during the approximate interval when a North Atlantic right whale experienced a mild entanglement along with the presence of white skin lesions. In the latter study, baleen corticosterone was at higher concentrations than cortisol, although marked variability in both GCs was evident for the entire data series, and any elevation in GCs was much less pronounced than in the current study. The disparity in baleen GC responses to entanglement in these studies may be because they are based on plates from single whales, species differences in adrenal responses, variation in the biological responses of these individuals to entanglements of varying severity, or temporal differences in the GC responses in these different studies. Additional research on a larger number of whales of differing sex and age-class is needed to determine the relative responsiveness of both GCs to different types of both natural (e.g., pregnancy, lactation) and anthropogenic stressors, to develop a reference dataset of baleen GC levels, and to better understand the biological relevance and temporal aspects of increased baleen hormone concentrations. Recent research on both terrestrial and marine species has suggested that the two GCs may signal independently, and, therefore, studies of acute and chronic stress should include analysis of both hormones (Koren et al. 2012, Chinn et al. 2018, DeRango et al. 2019). In conclusion, analysis of adrenal hormones extracted from baleen is a viable tool for monitoring the physiological effects of chronic entanglements in bowheads and other mysticetes. Serial sampling and analysis of GCs along the length of a baleen plate can provide a retrospective, longitudinal timeline of adrenal responses potentially over a decade or more, which can enhance management efforts with information on entanglement events, the timing (if coupled with stable isotope analysis) and, potentially, the geographic location of entanglements. This approach can also be applied to assess chronic stress responses to other environmental and anthropogenic factors impacting baleen whales because they are mediated through the same physiological pathway. Because of the integrative nature of adrenal stress hormones measured in baleen, a recent report by the National Academies of Sciences, Engineering and Medicine (2017) discussed application of this approach to investigate the cumulative effect of multiple stressors, and to investigate historical trajectories of stress responses based on museum specimens. In sum, baleen hormone analysis shows great promise as an approach for long-term monitoring of stress physiology to assess bowhead whale responses to the unprecedented environmental changes and increased human activity occurring in a rapidly changing Arctic ecosystem. We greatly appreciate the support for this study from the North Slope Borough Department of Wildlife Management biologists and staff. We are grateful to the Alaska Eskimo Whaling Commission and the whaling captains and crews from Utqiaġvik (Barrow), and Gambell, St. Lawrence Island, Alaska, for allowing us to obtain samples from these whales. Without their cooperation and assistance this research project would not have been possible. Our thanks also to Dave Ramey for assistance with sample packaging, coordination and shipment; and Malissa Langley, Janell Kaleak, Stephen Prophet and Thomas Williams for administrative assistance. We are grateful to Elizabeth Burgess for a very helpful review of this manuscript, Nadine Lysiak for providing archived baleen powder from the reference group of whales, and Scott Kraus for assistance with photographs and his deep knowledge of large whale entanglements. This study was funded by the NSB/Shell Baseline Studies Program Contract #2015-102. Marine mammal tissues collected for this study (baleen, blood, select tissues) occurred under NMFS permits (# 814-1899-00; #17350; # 17350-01) issued to the North Slope Borough Department of Wildlife Management. The authors have no conflict of interest to declare." @default.
W2938254257 created "2019-04-25" @default.
W2938254257 creator A5000369127 @default.
W2938254257 creator A5021416306 @default.
W2938254257 creator A5035568301 @default.
W2938254257 creator A5043568170 @default.
W2938254257 creator A5080747171 @default.
W2938254257 date "2019-03-25" @default.
W2938254257 modified "2023-10-16" @default.
W2938254257 title "Chronic stress from fishing gear entanglement is recorded in baleen from a bowhead whale (<i>Balaena mysticetus</i>)" @default.
W2938254257 cites W1973619396 @default.
W2938254257 cites W1977628496 @default.
W2938254257 cites W1986160539 @default.
W2938254257 cites W1989334744 @default.
W2938254257 cites W1994501861 @default.
W2938254257 cites W2000920921 @default.
W2938254257 cites W2003453604 @default.
W2938254257 cites W2005582511 @default.
W2938254257 cites W2006614358 @default.
W2938254257 cites W2025027920 @default.
W2938254257 cites W2038585822 @default.
W2938254257 cites W2043227319 @default.
W2938254257 cites W2052595529 @default.
W2938254257 cites W2063288985 @default.
W2938254257 cites W2066230852 @default.
W2938254257 cites W2068156022 @default.
W2938254257 cites W2074364102 @default.
W2938254257 cites W2082245886 @default.
W2938254257 cites W2084852947 @default.
W2938254257 cites W2086549040 @default.
W2938254257 cites W2094282763 @default.
W2938254257 cites W2097499286 @default.
W2938254257 cites W2103282102 @default.
W2938254257 cites W2103593412 @default.
W2938254257 cites W2107601928 @default.
W2938254257 cites W2122944480 @default.
W2938254257 cites W2126464292 @default.
W2938254257 cites W2127302010 @default.
W2938254257 cites W2133753630 @default.
W2938254257 cites W2149974356 @default.
W2938254257 cites W2168943246 @default.
W2938254257 cites W2170153270 @default.
W2938254257 cites W2312395397 @default.
W2938254257 cites W2320328969 @default.
W2938254257 cites W2320719725 @default.
W2938254257 cites W2332817257 @default.
W2938254257 cites W2335775186 @default.
W2938254257 cites W2337313760 @default.
W2938254257 cites W2460791980 @default.
W2938254257 cites W2520599246 @default.
W2938254257 cites W2520696655 @default.
W2938254257 cites W2537160999 @default.
W2938254257 cites W2555202063 @default.
W2938254257 cites W2564111664 @default.
W2938254257 cites W2580789555 @default.
W2938254257 cites W2593120665 @default.
W2938254257 cites W2754252301 @default.
W2938254257 cites W2764020636 @default.
W2938254257 cites W2767921502 @default.
W2938254257 cites W2771524575 @default.
W2938254257 cites W2802271758 @default.
W2938254257 cites W2804043318 @default.
W2938254257 cites W2810396816 @default.
W2938254257 cites W2882993520 @default.
W2938254257 cites W2888250317 @default.
W2938254257 cites W2891250612 @default.
W2938254257 cites W819914564 @default.
W2938254257 doi "https://doi.org/10.1111/mms.12596" @default.
W2938254257 hasPublicationYear "2019" @default.
W2938254257 type Work @default.
W2938254257 sameAs 2938254257 @default.
W2938254257 citedByCount "15" @default.
W2938254257 countsByYear W29382542572020 @default.
W2938254257 countsByYear W29382542572021 @default.
W2938254257 countsByYear W29382542572022 @default.
W2938254257 countsByYear W29382542572023 @default.
W2938254257 crossrefType "journal-article" @default.
W2938254257 hasAuthorship W2938254257A5000369127 @default.
W2938254257 hasAuthorship W2938254257A5021416306 @default.
W2938254257 hasAuthorship W2938254257A5035568301 @default.
W2938254257 hasAuthorship W2938254257A5043568170 @default.
W2938254257 hasAuthorship W2938254257A5080747171 @default.
W2938254257 hasBestOaLocation W29382542571 @default.
W2938254257 hasConcept C205649164 @default.
W2938254257 hasConcept C2777704720 @default.
W2938254257 hasConcept C2777803996 @default.
W2938254257 hasConcept C505870484 @default.
W2938254257 hasConcept C514101110 @default.
W2938254257 hasConcept C86803240 @default.
W2938254257 hasConcept C90856448 @default.
W2938254257 hasConcept C92878468 @default.
W2938254257 hasConceptScore W2938254257C205649164 @default.
W2938254257 hasConceptScore W2938254257C2777704720 @default.
W2938254257 hasConceptScore W2938254257C2777803996 @default.
W2938254257 hasConceptScore W2938254257C505870484 @default.
W2938254257 hasConceptScore W2938254257C514101110 @default.
W2938254257 hasConceptScore W2938254257C86803240 @default.
W2938254257 hasConceptScore W2938254257C90856448 @default.