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Crawford SG, Coker RH, O’Hara TM, Breed GA, Gelatt T, Fadely B, Burkanov V, Rivera PM, Rea LD. Fasting durations of Steller sea lion pups vary among subpopulations-evidence from two plasma metabolites. CONSERVATION PHYSIOLOGY 2023; 11:coad084. [PMID: 38026798 PMCID: PMC10673819 DOI: 10.1093/conphys/coad084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 08/28/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023]
Abstract
Geographic differences in population growth trends are well-documented in Steller sea lions (Eumetopias jubatus), a species of North Pacific pinniped listed under the U.S. Endangered Species Act in 1990 following a marked decline in population abundance that began during the 1970s. As population growth is intrinsically linked to pup production and survival, examining factors related to pup physiological condition provides useful information to management authorities regarding potential drivers of regional differences. During dam foraging trips, pups predictably transition among three fasting phases, distinguished by the changes in the predominant metabolic byproduct. We used standardized ranges of two plasma metabolites (blood urea nitrogen and β-hydroxybutyrate) to assign pups to fasting categories (n = 1528, 1990-2016, 12 subpopulations): Recently Fed-Phase I (digestion/assimilation-expected hepatic/muscle glycogen usage), Phase II (expected lipid utilization), transitioning between Phases II-III (expected lipid utilization with increased protein reliance), or Phase III (expected protein catabolism). As anticipated, the majority of pups were classified as Recently Fed-Phase I (overall mean proportion = 0.72) and few pups as Phase III (overall mean proportion = 0.04). By further comparing pups in Short (Recently Fed-Phase II) and Long (all other pups) duration fasts, we identified three subpopulations with significantly (P < 0.03) greater proportions of pups dependent upon endogenous sources of energy for extended periods, during a life stage of somatic growth and development: the 1) central (0.27 ± 0.09) and 2) western (0.36 ± 0.13) Aleutian Island (declining population trend) and 3) southern Southeast Alaska (0.32 ± 0.06; increasing population trend) subpopulations had greater Long fast proportions than the eastern Aleutian Islands (0.10 ± 0.05; stabilized population). Due to contrasting population growth trends among these highlighted subpopulations over the past 50+ years, both density-independent and density-dependent factors likely influence the dam foraging trip duration, contributing to longer fasting durations for pups at some rookeries.
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Affiliation(s)
- Stephanie G Crawford
- Department of Biology and Wildlife and Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775, USA
| | - Robert H Coker
- Montana Center for Work Physiology and Exercise Metabolism, University of Montana, 32 Campus Drive, Missoula, Montana 59812, USA
| | - Todd M O’Hara
- Veterinary Integrative Biosciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, 402 Raymond Stotzer Parkway, Bldg 2, College Station, Texas 77843, USA
| | - Greg A Breed
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA
| | - Tom Gelatt
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way N.E., Bldg. 4, Seattle, Washington 98115, USA
| | - Brian Fadely
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way N.E., Bldg. 4, Seattle, Washington 98115, USA
| | - Vladimir Burkanov
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way N.E., Bldg. 4, Seattle, Washington 98115, USA
| | - Patricia M Rivera
- Center for Alaska Native Health Research, Institute of Arctic Biology, University of Alaska Fairbanks, 2141 Koyukuk Drive, Fairbanks, Alaska 99775, USA
| | - Lorrie D Rea
- Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775, USA
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Cirino LA. Seasonal shift in diet affects female reproductive anatomy but not mating behavior. Oecologia 2023:10.1007/s00442-023-05398-7. [PMID: 37354252 DOI: 10.1007/s00442-023-05398-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 05/31/2023] [Indexed: 06/26/2023]
Abstract
Females experience considerable environmental variability when breeding seasons are long. Adverse nutritional conditions can result in a reduction in mating and reproduction. However, a return to good nutrition may help animals resume high reproductive investment. I tested the silver spoon hypothesis in which females raised under poor conditions are reproductively limited compared to those raised under good conditions regardless of their adult environment. I used a specialist herbivore, Narnia femorata (Hemiptera: Coreidae), that lives on seasonally changing cacti. I provided juveniles and adults with a cactus pad with fruit (good diet), without fruit (restricted diet), or an improved adult diet (no fruit as juveniles, fruit at adulthood) to simulate a seasonal change in their diets near the end of the breeding season. I found that both ovary size and egg presence were reduced for females fed the restricted diet compared to those fed the good diet. Females fed the improved diet grew large ovaries like those fed the good diet, but few produced any eggs. Interestingly, female mating behavior did not change but females were less attractive to males when fed restricted diets. My results support the silver spoon hypothesis for compensatory growth and suggest that tradeoffs may occur between early survival and future reproduction when females experience a poor early life diet.
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Affiliation(s)
- Lauren A Cirino
- Entomology & Nematology Department, University of Florida, Gainesville, FL, 32611, USA.
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Lapham Hall, 3209 N Maryland Ave, Milwaukee, WI, 53211, USA.
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Diaz Gomez M, Rosen DA, Forster IP, Trites AW. Prey composition impacts lipid and protein digestibility in northern fur seals (Callorhinus ursinus). CAN J ZOOL 2020. [DOI: 10.1139/cjz-2020-0007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pinnipeds have specific macronutrient (protein, lipid) requirements to satisfy physiological functions, yet little is known about how diet characteristics affect macronutrient digestibility. We measured relative and absolute lipid and protein digestibility in six female northern fur seals (Callorhinus ursinus (Linnaeus, 1758)) fed eight experimental diets composed variously of four prey species (Pacific herring, Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847; walleye pollock, Gadus chalcogrammus Pallas, 1814 (formerly Theragra chalcogramma (Pallas, 1814)); capelin, Mallotus villosus (Müller, 1776); magister armhook squid, Berryteuthis magister (Berry, 1913)). We quantified how digestibility was affected by proximate composition of the diet (% lipid or % protein), levels of food mass and macronutrient intake, and tested for any potential benefit of multi-species diets. Overall, digestibility of both protein and lipid were high across diets, although macronutrient retention of lipids (96.0%–98.4%) was significantly higher than protein (95.7%–96.7%) for all but the two highest protein diets. Increased levels of protein intake resulted in increased protein retention, but decreased lipid digestibility. There was no evidence that mixed-species diets provide greater macronutrient digestibility over single-species diets. The results suggest that high to moderate lipid diets are more beneficial to northern fur seals because they lead to increased levels of lipid retention without large decreases in protein digestibility. This raises concerns that dietary factors may be contributing to the population declines of northern fur seals in the Bering Sea.
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Affiliation(s)
- Mariana Diaz Gomez
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - David A.S. Rosen
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Ian P. Forster
- Pacific Science Enterprise Centre (PSEC), Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada
| | - Andrew W. Trites
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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Lander ME, Fadely BS, Gelatt TS, Sterling JT, Johnson DS, Pelland NA. Mixing it up in Alaska: Habitat use of adult female Steller sea lions reveals a variety of foraging strategies. Ecosphere 2020. [DOI: 10.1002/ecs2.3021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Michelle E. Lander
- Marine Mammal Laboratory Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Seattle Washington 98115 USA
| | - Brian S. Fadely
- Marine Mammal Laboratory Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Seattle Washington 98115 USA
| | - Thomas S. Gelatt
- Marine Mammal Laboratory Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Seattle Washington 98115 USA
| | - Jeremy T. Sterling
- Marine Mammal Laboratory Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Seattle Washington 98115 USA
| | - Devin S. Johnson
- Marine Mammal Laboratory Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Seattle Washington 98115 USA
| | - Noel A. Pelland
- Marine Mammal Laboratory Alaska Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration Seattle Washington 98115 USA
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Tollit D, Fritz L, Joy R, Miller K, Schulze A, Thomason J, Walker W, Zeppelin T, Gelatt T. Diet of endangered Steller sea lions (Eumetopias jubatus) in the Aleutian Islands: new insights from DNA detections and bioenergetic reconstructions. CAN J ZOOL 2017. [DOI: 10.1139/cjz-2016-0253] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The endangered western stock of Steller sea lion (Eumetopias jubatus (Schreber, 1776)) still declines in the western Aleutian Islands and accurate diet information is vital to test leading hypotheses. We undertook the first bioenergetic diet reconstruction using both molecular and hard part prey identifications from >600 scats collected in March–April 2008 and 2012. Atka mackerel (Pleurogrammus monopterygius (Pallas, 1810)) remained a primary prey (17%–27% by energy), but large (mean 60 cm) Pacific cod (Gadus macrocephalus Tilesius, 1810) also emerged as important prey (20%–24%) in a more diverse diet than previously reported, with Cottidae and smooth lumpsucker (Aptocyclus ventricosus (Pallas, 1769)) also contributing ∼10%. DNA detections highlighted a potentially important and previously underestimated prey, giant Pacific octopus (Enteroctopus dofleini (Wülker, 1910) (diet contribution 2%–15%, dependent on prey size assumptions). Although 504 unique DNA identifications resulted in significant increases for cephalopods, Pacific cod, and smooth lumpsucker, hard part alone species rankings were similar to composite ones and bioenergetic species rankings similar to occurrence-based ones. Retention or regurgitation of large cephalopod beaks, the removal of large cod heads, and skeletal fragility of lumpsuckers may explain these differences. DNA identifications provide valuable comparative and complementary prey occurrence data for pinnipeds, but composite diet estimates are optimal.
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Affiliation(s)
- Dominic Tollit
- SMRU Consulting North America, 1529 West 6th Avenue, Suite 510, Vancouver, BC V6J 1R1, Canada
| | - Lowell Fritz
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
| | - Ruth Joy
- SMRU Consulting North America, 1529 West 6th Avenue, Suite 510, Vancouver, BC V6J 1R1, Canada
| | - Kristi Miller
- Fisheries and Oceans Canada, Molecular Genetics Laboratory, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9K 6N7, Canada
| | - Angela Schulze
- Fisheries and Oceans Canada, Molecular Genetics Laboratory, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9K 6N7, Canada
| | - James Thomason
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
| | - William Walker
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
| | - Tonya Zeppelin
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
| | - Thomas Gelatt
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center, National Marine Mammal Laboratory, 7600 Sand Point Way Northeast, Seattle, WA 98115, USA
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Sattler R, Polasek L. Serum estradiol and progesterone profiles during estrus, pseudopregnancy, and active gestation in Steller sea lions. Zoo Biol 2017; 36:323-331. [PMID: 28901587 DOI: 10.1002/zoo.21381] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 08/24/2017] [Accepted: 08/24/2017] [Indexed: 12/29/2022]
Abstract
While the proximate driver behind the decline of the Western stock of Steller sea lions (Eumetopias jubatus, >80% since 1970s) is likely multifactorial, the population reduction may have been powered by a decrease in fecundity. A harvest of Steller sea lions in the 1970s and 80s revealed a 30% reduction in the proportion of pregnant females from early (October-November) to late gestation (April-May). Identification and quantification of these reproductive failures are difficult when we lack species-specific data on endocrinology associated with discrete stages of the reproductive cycle (i.e., estrus, implantation, and gestation). We tracked changes in serum estradiol and progesterone in three adult female Steller sea lions from 2011 to 2015. In all years and most females, a discrete increase in estradiol was observed during the breeding season (June-August), indicative of estrus. Estradiol concentrations from October to May in a pregnant female compared to her corresponding values when non-pregnant did not consistently differ through gestation. An elevation in progesterone was observed in all females and all years beginning approximately in June and lasting through November. This likely results from progesterone production by the corpus luteum in both pregnant and pseudopregnant females. Serum progesterone shows promise as a diagnostic tool to identify pregnancy during months 3-5 (December-February) of the 8-month active gestation following embryonic implantation. This study provides ranges of key hormones during estrus, embryonic diapause/pseudopregnancy, and gestation in pregnant and non-pregnant females for studying reproduction in Steller sea lions.
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Affiliation(s)
| | - Lori Polasek
- Alaska Sea Life Center, Seward, Alaska.,Institute of Marine Science, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska
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Rosen DAS, Hindle AG, Gerlinsky CD, Goundie E, Hastie GD, Volpov BL, Trites AW. Physiological constraints and energetic costs of diving behaviour in marine mammals: a review of studies using trained Steller sea lions diving in the open ocean. J Comp Physiol B 2016; 187:29-50. [PMID: 27686668 DOI: 10.1007/s00360-016-1035-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 08/26/2016] [Accepted: 09/13/2016] [Indexed: 10/20/2022]
Abstract
Marine mammals are characterized as having physiological specializations that maximize the use of oxygen stores to prolong time spent under water. However, it has been difficult to undertake the requisite controlled studies to determine the physiological limitations and trade-offs that marine mammals face while diving in the wild under varying environmental and nutritional conditions. For the past decade, Steller sea lions (Eumetopias jubatus) trained to swim and dive in the open ocean away from the physical confines of pools participated in studies that investigated the interactions between diving behaviour, energetic costs, physiological constraints, and prey availability. Many of these studies measured the cost of diving to understand how it varies with behaviour and environmental and physiological conditions. Collectively, these studies show that the type of diving (dive bouts or single dives), the level of underwater activity, the depth and duration of dives, and the nutritional status and physical condition of the animal affect the cost of diving and foraging. They show that dive depth, dive and surface duration, and the type of dive result in physiological adjustments (heart rate, gas exchange) that may be independent of energy expenditure. They also demonstrate that changes in prey abundance and nutritional status cause sea lions to alter the balance between time spent at the surface acquiring oxygen (and offloading CO2 and other metabolic by-products) and time spent at depth acquiring prey. These new insights into the physiological basis of diving behaviour further our understanding of the potential scope for behavioural responses of marine mammals to environmental changes, the energetic significance of these adjustments, and the consequences of approaching physiological limits.
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Affiliation(s)
- David A S Rosen
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Allyson G Hindle
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Carling D Gerlinsky
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Elizabeth Goundie
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Gordon D Hastie
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Beth L Volpov
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Andrew W Trites
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
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8
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Diaz Gomez M, Rosen DA, Trites AW. Net energy gained by northern fur seals (Callorhinus ursinus) is impacted more by diet quality than by diet diversity. CAN J ZOOL 2016. [DOI: 10.1139/cjz-2015-0143] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Understanding whether northern fur seals (Callorhinus ursinus (L., 1758)) are negatively affected by changes in prey quality or diversity could provide insights into their on-going population decline in the central Bering Sea. We investigated how six captive female fur seals assimilated energy from eight different diets consisting of four prey species (walleye pollock (Gadus chalcogrammus Pallas, 1814, formerly Theragra chalcogrammus (Pallas, 1814)), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847), capelin (Mallotus villosus (Müller, 1776)), and magister armhook squid (Berryteuthis magister (Berry, 1913))) fed alone or in combination. Net energy was quantified by measuring fecal energy loss, urinary energy loss, and heat increment of feeding. Digestible energy (95.9%–96.7%) was high (reflecting low fecal energy loss) and was negatively affected by ingested mass and dietary protein content. Urinary energy loss (9.3%–26.7%) increased significantly for high-protein diets. Heat increment of feeding (4.3%–12.4%) was significantly lower for high-lipid diets. Overall, net energy gain (57.9%–83.0%) was affected by lipid content and varied significantly across diets. Mixed-species diets did not provide any energetic benefit over single-species diets. Our study demonstrates that diet quality was more important in terms of energy gain than diet diversity. These findings suggest that fur seals consuming low-quality prey in the Bering Sea would be more challenged to obtain sufficient energy to satisfy energetic and metabolic demands, independent of high prey abundance.
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Affiliation(s)
- Mariana Diaz Gomez
- Department of Zoology and Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Zoology and Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - David A.S. Rosen
- Department of Zoology and Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Zoology and Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Andrew W. Trites
- Department of Zoology and Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Zoology and Marine Mammal Research Unit, Institute for the Oceans and Fisheries, Room 247, 2202 Main Mall, AERL, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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Shuert C, Mellish J, Horning M. Physiological predictors of long-term survival in juvenile Steller sea lions (Eumetopias jubatus). CONSERVATION PHYSIOLOGY 2015; 3:cov043. [PMID: 27293728 PMCID: PMC4778442 DOI: 10.1093/conphys/cov043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Revised: 08/13/2015] [Accepted: 08/20/2015] [Indexed: 06/06/2023]
Abstract
This study builds on a continued effort to document potential long-term research impacts on the individual, as well as to identify potential markers of survival for use in a field framework. The Transient Juvenile Steller sea lion (TJ) project was developed as a novel framework to gain access to wild individuals. We used three analyses to evaluate and predict long-term survival in temporarily captive sea lions (n = 45) through Cormack-Jolly-Seber open population modelling techniques. The first analysis investigated survival in relation to the observed responses to handling stress through changes in six principal blood parameters over the duration of captivity. The second analysis evaluated survival compared with body condition and mass at entry and exit from captivity. Finally, the third analysis sought to evaluate the efficacy of single-point sampling to project similar survival trends for use in field sampling operations. Results from a priori models ranked through Akaike information criterion model selection methods indicated that mass gains (4.2 ± 12%) over captivity and increases in leucocytes (WBC, 1.01 ± 3.54 × 10(3)/mm(3)) resulted in a higher average survival rate (>3 years). Minor support was identified for the single-point measures of exit mass and entry WBC. A higher exit mass predicted a higher survival rate, whereas a higher WBC predicted a lower survival rate. While changes in mass and WBC appear to be the best predictors of survival when measured as a change over time, single-point sampling may still be an effective way to improve estimates of population health.
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Affiliation(s)
- C. Shuert
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
- Alaska SeaLife Center, 301 Railway Avenue, Seward, AK 99664, USA
| | - J. Mellish
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
- Alaska SeaLife Center, 301 Railway Avenue, Seward, AK 99664, USA
- North Pacific Research Board, Anchorage, AK 99501, USA
| | - M. Horning
- Alaska SeaLife Center, 301 Railway Avenue, Seward, AK 99664, USA
- Department of Fisheries and Wildlife, Oregon State University, Newport, OR 97365, USA
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Dalton A, Rosen D, Trites A. Resting metabolic rate and activity: key components of seasonal variation in daily energy expenditure for the northern fur seal (Callorhinus ursinus). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0313] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Seasonal changes in daily energy expenditure (DEE) and its key underlying components (costs of resting metabolic rate (RMR), thermoregulation, activity, and growth) were measured to determine seasonal energy requirements, bioenergetic priorities, and potential times of year when unpredicted episodes of nutritional stress would have their greatest effect on female northern fur seals (Callorhinus ursinus (L., 1758)). The mean (±SD) DEE of six captive juvenile female fur seals was 527.8 ± 65.7 kJ·kg−1·d−1 and fluctuated seasonally (lower during summer and winter, and up to 20% greater in spring and fall). RMR also changed significantly with season and was higher in the fall (potentially due to moulting or anticipated migratory activity). However, changes in RMR did not follow the same seasonal trend as those of DEE. The largest component of DEE was RMR (∼80%, on average), followed by the cost of activity (which may have driven some of the seasonal variations in DEE). In contrast, the energetic costs associated with growth and thermoregulation appeared negligible within the scope of overall energy expenditures. Elevated innate costs of RMR and higher growth rates in the fall and summer, respectively, suggest that inadequate nutrition could comparatively have greater negative effects on female fur seals during these seasons.
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Affiliation(s)
- A.J.M. Dalton
- Marine Mammal Research Unit, Fisheries Centre and Department of Zoology, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
- Marine Mammal Research Unit, Fisheries Centre and Department of Zoology, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - D.A.S. Rosen
- Marine Mammal Research Unit, Fisheries Centre and Department of Zoology, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
- Marine Mammal Research Unit, Fisheries Centre and Department of Zoology, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - A.W. Trites
- Marine Mammal Research Unit, Fisheries Centre and Department of Zoology, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
- Marine Mammal Research Unit, Fisheries Centre and Department of Zoology, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
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11
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Spitz J, Becquet V, Rosen DAS, Trites AW. A nutrigenomic approach to detect nutritional stress from gene expression in blood samples drawn from Steller sea lions. Comp Biochem Physiol A Mol Integr Physiol 2015; 187:214-23. [PMID: 25700740 DOI: 10.1016/j.cbpa.2015.02.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 02/04/2015] [Accepted: 02/08/2015] [Indexed: 02/07/2023]
Abstract
Gene expression profiles are increasingly being used as biomarkers to detect the physiological responses of a number of species to disease, nutrition, and other stressors. However, little attention has been given to using gene expression to assess the stressors and physiological status of marine mammals. We sought to develop and validate a nutrigenomic approach to quantify nutritional stress in Steller sea lions (Eumetopias jubatus). We subjected 4 female Steller sea lions to 3 feeding regimes over 70-day trials (unrestricted food intake, acute nutritional stress, and chronic nutritional stress), and drew blood samples from each animal at the end of each feeding regime. We then extracted the RNA of white blood cells and measured the response of 8 genes known to react to diet restriction in terrestrial mammals. Overall, we found that the genomic response of Steller sea lions experiencing nutritional stress was consistent with how terrestrial mammals respond to dietary restrictions. Our nutritionally stressed sea lions down-regulated some cellular processes involved in immune response and oxidative stress, and up-regulated pro-inflammatory responses and metabolic processes. Nutrigenomics appears to be a promising means to monitor nutritional status and contribute to mitigation measures needed to assist in the recovery of Steller sea lions and other at-risk species of marine mammals.
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Affiliation(s)
- Jérôme Spitz
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada.
| | - Vanessa Becquet
- Littoral Environnement et Sociétés, UMR 7266 Université de La Rochelle/CNRS, 2 rue Olympe de Gouges, 17042 La Rochelle, Cedex, France
| | - David A S Rosen
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Andrew W Trites
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
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Noren SR, Udevitz MS, Jay CV. Energy demands for maintenance, growth, pregnancy, and lactation of female Pacific walruses (Odobenus rosmarus divergens). Physiol Biochem Zool 2014; 87:837-54. [PMID: 25461648 DOI: 10.1086/678237] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Decreases in sea ice have altered habitat use and activity patterns of female Pacific walruses Odobenus rosmarus divergens and could affect their energetic demands, reproductive success, and population status. However, a lack of physiological data from walruses has hampered efforts to develop the bioenergetics models required for fully understanding potential population-level impacts. We analyzed long-term longitudinal data sets of caloric consumption and body mass from nine female Pacific walruses housed at six aquaria using a hierarchical Bayesian approach to quantify relative energetic demands for maintenance, growth, pregnancy, and lactation. By examining body mass fluctuations in response to food consumption, the model explicitly uncoupled caloric demand from caloric intake. This is important for pinnipeds because they sequester and deplete large quantities of lipids throughout their lifetimes. Model outputs were scaled to account for activity levels typical of free-ranging Pacific walruses, averaging 83% of the time active in water and 17% of the time hauled-out resting. Estimated caloric requirements ranged from 26,900 kcal d(-1) for 2-yr-olds to 93,370 kcal d(-1) for simultaneously lactating and pregnant walruses. Daily consumption requirements were higher for pregnancy than lactation, reflecting energetic demands of increasing body size and lipid deposition during pregnancy. Although walruses forage during lactation, fat sequestered during pregnancy sustained 27% of caloric requirements during the first month of lactation, suggesting that walruses use a mixed strategy of capital and income breeding. Ultimately, this model will aid in our understanding of the energetic and population consequences of sea ice loss.
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Affiliation(s)
- Shawn R Noren
- Institute of Marine Science, University of California, Santa Cruz, California 95060; 2US Geological Survey, Alaska Science Center, Anchorage, Alaska 99508
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Gerlinsky CD, Trites AW, Rosen DAS. Steller sea lions (Eumetopias jubatus) have greater blood volumes, higher diving metabolic rates and a longer aerobic dive limit when nutritionally stressed. ACTA ACUST UNITED AC 2013; 217:769-78. [PMID: 24198263 DOI: 10.1242/jeb.089599] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Marine mammal foraging behaviour inherently depends on diving ability. Declining populations of Steller sea lions may be facing nutritional stress that could affect their diving ability through changes in body composition or metabolism. Our objective was to determine whether nutritional stress (restricted food intake resulting in a 10% decrease in body mass) altered the calculated aerobic dive limit (cADL) of four captive sea lions diving in the open ocean, and how this related to changes in observed dive behaviour. We measured diving metabolic rate (DMR), blood O2 stores, body composition and dive behaviour prior to and while under nutritional restriction. We found that nutritionally stressed sea lions increased the duration of their single long dives, and the proportion of time they spent at the surface during a cycle of four dives. Nutritionally stressed sea lions lost both lipid and lean mass, resulting in potentially lower muscle O2 stores. However, total body O2 stores increased due to rises in blood O2 stores associated with having higher blood volumes. Nutritionally stressed sea lions also had higher mass-specific metabolic rates. The greater rise in O2 stores relative to the increase in mass-specific DMR resulted in the sea lions having a longer cADL when nutritionally stressed. We conclude that there was no negative effect of nutritional stress on the diving ability of sea lions. However, nutritional stress did lower foraging efficiency and require more foraging time to meet energy requirements due to increases in diving metabolic rates and surface recovery times.
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Affiliation(s)
- Carling D Gerlinsky
- Marine Mammal Research Unit, Fisheries Center and Department of Zoology, University of British Columbia, 2204 Main Mall, Vancouver, British Columbia, Canada, V6T 1Z4
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Rosen D, Young B, Trites A. Rates of maximum food intake in young northern fur seals (Callorhinus ursinus) and the seasonal effects of food intake on body growth. CAN J ZOOL 2012. [DOI: 10.1139/z11-112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accurate estimates of food intake and its subsequent effect on growth are required to understand the interaction between an animal’s physiology and its biotic environment. We determined how food intake and growth of six young northern fur seals ( Callorhinus ursinus (L., 1758)) responded seasonally to changes in food availability. Animals were given unrestricted access to prey for 8 h·day–1 on either consecutive days or on alternate days only. We found animals offered ad libitum food on consecutive days substantially increased their food intake over normal “training” levels. However, animals that fasted on alternate days were unable to compensate by further increasing their levels of consumption on subsequent feeding days. Absolute levels of food intake were highly consistent during winter and summer trials (2.7–2.9 kg·day–1), but seasonal differences in body mass meant that fur seals consumed more food relative to their body mass in summer (~27%) than in winter (~20%). Despite significant increases in absolute food intake during both seasons, the fur seals did not appear to efficiently convert this additional energy into mass growth, particularly in the winter. These seasonal differences in conversion efficiencies and estimates of maximum intake rates can be used to generate physiologically realistic predictions about the effect of changes in food availability on an individual fur seal, as well as the consequences for an entire population.
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Affiliation(s)
- D.A.S. Rosen
- Marine Mammal Research Unit, Fisheries Centre, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - B.L. Young
- Marine Mammal Research Unit, Fisheries Centre, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - A.W. Trites
- Marine Mammal Research Unit, Fisheries Centre, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
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