Retrospective analysis of the lifetime endocrine response of southern right whale calves to gull wounding and harassment: A baleen hormone approach

Ajó, Alejandro A. Fernández; Hunt, Kathleen E.; Giese, Adriana Carolina; Sironi, Mariano; Uhart, Marcela; Rowntree, Victoria J.; Marón, Carina F.; Dillon, Danielle; DiMartino, Matias; Buck, C. Loren

doi:10.1016/j.ygcen.2020.113536

Cited by 20 publications

(15 citation statements)

References 56 publications

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“…During this period of baleen growth (2012–2016), the North Pacific marine ecosystem experienced a severe heatwave from 2014 to 2016 that resulted in increased sea surface temperatures (anomalies greater than +3°C; Cavole et al, 2016 , Di Lorenzo and Mantua, 2016 ) and weakened coastal upwellings that could have contributed to this whale’s nutritional stress. A similar rise-then-fall pattern in GCs has been documented in baleen of southern right whale ( Eubalaena australis ) calves with chronic wounding from kelp gulls ( Fernández Ajó et al, 2018 ; Fernández Ajó et al, 2020 ). In these calves, baleen GCs gradually increased as wounding became more severe, and then abruptly decreased to baseline or lower immediately before death.…”

Section: Discussionsupporting

confidence: 66%

“…Physiological state is most commonly assessed via blood sampling, but that requires animals to be handled (in captivity or by trapping), neither of which are feasible for baleen whales. Non-traditional sample media have instead been used to inform physiological state, including earplugs ( Trumble et al , 2013 ; Trumble et al, 2018 ) or baleen ( Hunt et al , 2017a ; Hunt et al , 2017b ; Fernández Ajó et al, 2018 , Hunt et al, 2018 ; Fernández et al, 2020 ) from dead whales. In live whales, measures of stress response have been obtained from feces ( Hunt et al, 2006, 2019 ; Pérez et al, 2011 ; Hunt et al , 2014a ; Corkeron et al , 2017 ; Rolland et al, 2017 ; Valenzuela-Molina et al , 2018 ), respiratory vapour ( Burgess et al , 2018 ; Mingramm et al , 2019 ) or blubber ( Pallin et al , 2018 ; Teerlink et al , 2018 ; Mingramm et al , 2020 ).…”

Section: Introductionmentioning

confidence: 99%

“…Baleen is an especially promising sample type for long-term stress and reproductive analysis because hormones are incorporated into the keratinous baleen plate as it grows ( Hunt et al, 2016 , 2017b , 2018 ; Fernández et al, 2018, 2020 ). Since baleen grows slowly and continuously over many years, a single baleen plate can hold a retrospective longitudinal record at approximately a monthly or bimonthly resolution, depending on sampling distance, of the concentrations of GCs in the whale over the baleen growth record.…”

Section: Introductionmentioning

confidence: 99%

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Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Lowe

Hunt

Robbins

et al. 2021

Conservation Physiology

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Baleen whales are subject to a myriad of natural and anthropogenic stressors, but understanding how these stressors affect physiology is difficult. Measurement of adrenal glucocorticoid (GC) hormones involved in the vertebrate stress response (cortisol and corticosterone) in baleen could help fill this data gap. Baleen analysis is a powerful tool, allowing for a retrospective re-creation of multiple years of GC hormone concentrations at approximately a monthly resolution. We hypothesized that whales that died from acute causes (e.g. ship strike) would have lower levels of baleen GCs than whales that died from extended illness or injury (e.g. long-term entanglement in fishing gear). To test this hypothesis, we extracted hormones from baleen plates of four humpback whales (Megaptera novaeangliae) with well-documented deaths including multiple and chronic entanglements (n = 1, female), ship strike (n = 2, male and female) and chronic illness with nutritional stress (n = 1, male). Over ~3 years of baleen growth and during multiple entanglements, the entangled whale had average corticosterone levels of 80–187% higher than the other three whales but cortisol levels were similar to two of the other three whales. The nutritionally stressed and chronically ill whale showed a slow increase in both cortisol and corticosterone spanning ~3 years, followed by a sharp decline in both hormones before death, possibly indicative of adrenal failure in this moribund individual. This whale’s correlation between cortisol and corticosterone was significant but there were no correlations in the other three whales. Our results show that cortisol and corticosterone concentrations vary according to the type and duration of illness or injury. Single-point GC concentrations should be interpreted with caution as low values can occur in whales experiencing pronounced stress and individual baselines can be highly variable. Baleen analysis is a promising tissue type for retrospective analyses of physiological responses to various stressors affecting baleen whales.

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Section: Discussionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Lowe

Hunt

Robbins

et al. 2021

Conservation Physiology

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“…Our results are also consistent with a recent study that found no differences in the fatty acid profiles of living and dead calves in Península Valdés, which indicates no evidence of inefficient transfer of fatty acids from mothers to calves or variation in maternal diets. Also, another study in dead calves of this population showed stable levels of triiodothyronine (T3), a metabolic hormone that decreases under nutritional stress (Fernández Ajó et al, 2020). Notwithstanding, although we found no evidence of thinner blubber or less fat content in calves that died during high mortality years, a nutritional factor cannot be ruled out as a contributor to calf deaths in those years.…”

Section: Discussionmentioning

confidence: 96%

Patterns of blubber fat deposition and evaluation of body condition in growing southern right whale calves (Eubalaena australis)

Marón

Lábaque

Beltramino

et al. 2021

Marine Mammal Science

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Marine mammals rely on blubber mainly for energy storage, buoyancy, and streamlining. Mysticetes are born with a relatively thin fat layer that grows rapidly during nursing. However, little information on blubber deposition patterns is available for baleen whale calves. We measured blubber thickness at nine body locations in 350 southern right whale (Eubalaena australis) newborn to 4–6‐month‐old calves that died on the Península Valdés (Argentina) calving ground from 2003 to 2019, to document changes in blubber thickness with growth. Additionally, we looked for differences in blubber thickness and lipid content of the outer/superficial blubber in calves that died in years with high (2003, 2005, 2007–2013) and low calf mortality (2004, 2006, 2014–2019) to test whether the former were suffering from gross nutritional stress. Blubber thickness increased at all body locations with calf length. Along the cranio‐caudal axis, blubber increased in the dorsal and ventral planes, but decreased laterally towards the peduncle, possibly to improve streamlining. We found no difference in blubber thickness and lipid content between high and low mortality years, suggesting that individuals were not undernourished. This is the first study to describe progressive increases in calf blubber during growth and contributes knowledge to right whale health and ontogeny.

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“…Glucocorticoids are traditionally measured in plasma, but plasma sampling from free-ranging large whales is currently impossible. However, alternative sample types such as fecal samples, baleen, respiratory vapor, and blubber can be utilized to quantify GCs in large whales (Rolland et al 2005(Rolland et al , 2017Hunt et al 2006Hunt et al , 2014Hunt et al , 2019Hogg et al 2009;Fernández Ajó et al 2020). The analyses of fecal glucocorticoid metabolites (fGCm) have proven particularly useful for endocrine assessments of free-swimming whales, with several studies showing that fGCm correlate in meaningful ways with presumed stressors.…”

Section: Introductionmentioning

confidence: 99%

Potential endocrine correlation with exposure to domoic acid in Southern Right Whale (Eubalaena australis) at the Península Valdés breeding ground

et al. 2021

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In waters off Península Valdés (PV), Argentina, southern right whales (SRW, Eubalaena australis) are occasionally exposed to domoic acid (DA), a neurotoxin produced by diatoms of the genus Pseudo-nitzschia. Domoic acid toxicity in marine mammals can cause gastrointestinal and neurological clinical signs, alterations in hematologic and endocrine variables, and can be fatal in extreme cases. In this study, we validated an enzyme immunoassay to quantify fecal glucocorticoid metabolites (fGCm) in 16 SRW fecal samples from live and dead stranded whales in PV from 2013 to 2018 and assessed fGCm levels associated with DA exposure. Overall, fGCm levels were significantly lower in SRWs with detectable fecal DA (n = 3) as compared to SRWs with undetectable fecal DA levels (n = 13). The highest fecal DA was observed in a live lactating female, which had low fGCm compared to the other lactating females studied. The highest fGCm was observed in a lactating female with undetectable DA; interestingly, at the time of sample collection, this female was sighted with two calves, an extremely unusual occurrence in this species. Though the sample size of these exceptionally rare breeding-season fecal samples was unavoidably small, our study provides evidence of potential adrenal alterations in whales exposed to an environmental neurotoxin such as DA.

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Retrospective analysis of the lifetime endocrine response of southern right whale calves to gull wounding and harassment: A baleen hormone approach

Cited by 20 publications

References 56 publications

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Patterns of blubber fat deposition and evaluation of body condition in growing southern right whale calves (Eubalaena australis)

Potential endocrine correlation with exposure to domoic acid in Southern Right Whale (Eubalaena australis) at the Península Valdés breeding ground

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