Lifetime glucocorticoid profiles in baleen of right whale calves: Potential relationships to chronic stress of repeated wounding by Kelp Gulls

Baleen tissue accumulates stress hormones (glucocorticoids, GC) as it grows, along with other adrenal, gonadal and thyroid hormones. The hormones are deposited in a linear fashion such that a single plate of baleen allows retrospective assessment and evaluation of long-term trends in the whales´ physiological condition. In whale calves, a single piece of baleen contains hormones deposited across the lifespan of the animal, with the tip of the baleen representing prenatally grown baleen. This suggests that baleen recovered from stranded carcasses of whale calves could be used to examine lifetime patterns of stress physiology. Here we report lifetime profiles of cortisol and corticosterone in baleen of a North Atlantic right whale ("NARW" - Eubalaena glacialis) calf that died from a vessel strike, as well as four southern right whale ("SRW" - Eubalaena australis) calves that were found dead with varying severity of chronic wounding from Kelp Gull (Larus dominicanus) attacks. In all five calves, prenatally grown baleen exhibited a distinctive profile of elevated glucocorticoids that declined shortly before birth, similar to GC profiles reported from baleen of pregnant females. After birth, GC profiles in calf baleen corresponded with the degree of wounding. The NARW calf and two SRW calves with no or few gull wounds had relatively low and constant GC content throughout life, while two SRW calves with high numbers of gull wounds had pronounced elevations in baleen GC content in postnatal baleen followed by a precipitous decline shortly before death, a profile suggestive of prolonged chronic stress. Baleen samples may present a promising and valuable tool for defining the baseline physiology of whale calves and may prove useful for addressing conservation-relevant questions such as distinguishing acute from chronic stress and, potentially, determining cause of death.Fil: Ajó, Alejandro A. Fernández. Northern Arizona University; Estados UnidosFil: Hunt, Kathleen E.. Northern Arizona University; Estados UnidosFil: Uhart, Marcela María. University of California at Davis; Estados UnidosFil: Rowntree, Victoria. University of Utah; Estados UnidosFil: Sironi, Mariano. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica; Argentina. Instituto de Conservación de Ballenas; ArgentinaFil: Marón, Carina Flavia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica; Argentina. Instituto de Conservación de Ballenas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Di Martino, Matias. Southern Right Whale Health Monitoring Program; ArgentinaFil: Buck, Charles Loren. Northern Arizona University; Estados Unido

Patrones de abastecimiento de presas en relación con la edad de pollos en el Gaviotín Sudamericano (Sterna hirundinacea)

The study of temporal patterns in diet composition is crucial to interpret adequately severalaspects of seabird ecology and life history. The variation in prey composition and prey size in relation tochick age were evaluated in a South American Tern (Sterna hirundinacea) colony at Punta Loma, Argentina, during the 2006 breeding season. The diet of South American Tern chicks consisted of at least 12 prey items. Fish, mostly Argentine anchovy (Engraulis anchoita) and silverside (Odontesthes argentinensis) were the main prey delivered (91%) to the chicks. The relative proportion of prey types varied amongchick age-classes and the proportion of Argentine anchovy in the diet increased with chick age, reaching 58% in older chicks. Larger prey items were delivered to older chicks. Prey stolen by other adult ternswas significantly larger than the prey actually consumed by the chicks. South American terns at thePunta Loma colony appear to confront the increasing demand of growing chicks by increasing the qualityof prey in each feeding trip, reflected in larger and more energetic prey.El estudio de los patrones temporales en la composiciónde la dieta es clave para interpretar ciertos aspectos de la ecología e historia de vida de las aves marinas. La variación en la composición y tamaño de presas en relación con la edad de los pollos fue evaluado en una colonia de Gaviotín Sudamericano (Sterna hirundinacea) en Punta Loma, Argentina, durantela temporada reproductiva del 2006. La dieta de los pollos de Gaviotín Sudamericano incluyó al menos12 especies de presa. El pescado, mayormente anchoíta (Engraulis anchoita) y pejerrey (Odontesthesargentinensis) fue la principal presa entregada (91%) a los pollos. La proporción relativa de tipos depresa varió entre las clases de edad de los pollos, y la proporción de Anchoíta en la dieta se incrementócon la edad de los mismos, alcanzando el 58% en las crías mayores. El tamaño de las presas aumentócon la edad de los pollos. Las presas robadas por otros gaviotines adultos fueron significativamente másgrandes que aquellas consumidas por los pollos. Los Gaviotines Sudamericanos en la colonia de Punta Loma parecen enfrentar la demanda creciente de los pollos en crecimiento aumentando la calidad de lapresa en cada viaje de alimentación, reflejada tanto en presas más grandes como de mayor contenido energético.Fil: Fernández Ajó, Alejandro A.. Universidad Nacional de la Patagonia “San Juan Bosco”; ArgentinaFil: Gatto, Alejandro Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Yorio, Pablo Martin. Wildlife Conservation Society; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin

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

Physiological measurements are informative in assessing the relative importance of stressors that potentially impact the health of wildlife. Kelp Gulls, Larus dominicanus (KG), resident to the region of Península Valdés, Argentina, have developed a unique behavior of landing on the backs of southern right whale adults and calves, Eubalaena australis (SRW), where they feed on their skin and blubber. This parasitic behavior results in large open wounds on the dorsal surface of the whale. Coincidently, the SRW population off the coast of Península Valdés has experienced elevated calf mortality. We quantified levels of glucocorticoids and thyroid hormone extracted from baleen of dead calves to evaluate, retrospectively, the endocrine response of whale calves to gull wounding and harassment. Baleen accumulates hormones as it grows, allowing evaluation of long-term trends in physiological condition. While glucocorticoids (GCs) are known to increase in response to stressors such as disturbance, the metabolic hormone triiodothyronine (T3) has been shown to decrease under sustained food deprivation but is largely unaffected by disturbance stress. We quantified lifetime patterns of GCs and T3 in baleen recovered at necropsy from 36 southern right whale calves with varying severity of wounding from KGs. GC levels in baleen correlated positively with the degree of wounding, while T3 levels remained stable irrespective of the severity of the wounding. Our results suggest no evidence of malnutrition in low vs. severely wounded whales. However, the positive correlation of GCs with wound severity indicates that heavily wounded calves are suffering high levels of physiological stress before they die. This suggests that KG wounding may have contributed to the high southern right whale calf mortality observed in the Península Valdés region of Argentina.Fil: Fernández Ajó, Alejandro A.. Northern Arizona University; Estados UnidosFil: Hunt, Kathleen E.. George Mason University; Estados UnidosFil: Giese, Adriana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Sironi, Mariano. Universidad Nacional de Córdoba; Argentina. Instituto de Conservación de Ballenas; ArgentinaFil: Uhart, Marcela María. University of California; Estados UnidosFil: Rowntree, Victoria J.. Instituto de Conservación de Ballenas; Argentina. University of Utah; Estados UnidosFil: Marón, Carina Flavia. Instituto de Conservación de Ballenas; Argentina. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dillon, Danielle. Northern Arizona University; Estados UnidosFil: DiMartino, Matias. Southern Right Whale Health Monitoring Program; ArgentinaFil: Buck, C. Loren. Northern Arizona University; Estados Unido

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

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.Fil: Marón, Carina Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica; ArgentinaFil: Lábaque, María Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Ciencias y Tecnología de los Alimentos; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica; ArgentinaFil: Beltramino, Lucas Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Southern Right Whale Health Monitoring Program. Puerto Madryn; ArgentinaFil: Di Martino, Matías. Southern Right Whale Health Monitoring Program. Puerto Madryn; ArgentinaFil: Alzugaray, Lucía. Southern Right Whale Health Monitoring Program. Puerto Madryn; ArgentinaFil: Ricciardi, Marcos. Instituto de Conservación de Ballenas, Ciudad Autónoma de Buenos Aires; ArgentinaFil: Fernández Ajó, Alejandro A.. Instituto de Conservación de Ballenas, Ciudad Autónoma de Buenos Aires; Argentina. Northern Arizona University; Estados UnidosFil: Adler, Frederick R.. University of Utah; Estados UnidosFil: Seger, Jon. University of Utah; Estados UnidosFil: Sironi, Mariano. Instituto de Conservación de Ballenas, Ciudad Autónoma de Buenos Aires; Argentina. Southern Right Whale Health Monitoring Program. Puerto Madryn; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica; ArgentinaFil: Rowntree, Victoria J.. University of Utah; Estados Unidos. Southern Right Whale Health Monitoring Program. Puerto Madryn; Argentina. Instituto de Conservación de Ballenas, Ciudad Autónoma de Buenos Aires; ArgentinaFil: Uhart, Marcela María. Southern Right Whale Health Monitoring Program. Puerto Madryn; Argentina. University of California at Davis. Department of Wildlife, Fish, and Conservation Biology; Estados Unido