[MARMAM] New article: Vibrissal growth parameters of southern elephant seals Mirounga leonina
Dear colleagues, My co-authors and I would like to share with you our work recently published in Marine Ecology Progress Series: Lübcker N, Condit R, Beltran RS, de Bruyn PJN, Bester MN. 2016. Vibrissal growth parameters of southern elephant seals Mirounga leonina: obtaining fine-scale, time-based stable isotope data. Marine Ecology Progress Series 559: 243-255. doi: 10.3354/meps11899. Article available at http://www.int-res.com/abstracts/meps/v559/p243-255/ ABSTRACT: Stable isotopes provide a powerful, indirect approach to assess the trophic ecology of individuals on a spatial and temporally integrated basis (especially when combined with telemetry). However, using stable isotopes requires accurate, species-specific quantification of the period of biomolecule deposition in the sampled tissue. Sequentially sampled vibrissae (whiskers) provide a chronology of biogeochemical data, although knowledge of vibrissal growth is required for temporal interpretations. We sampled vibrissae from southern elephant seals Mirounga leonina (hereafter SES) at Marion Island, southern Indian Ocean, to address the following aims: (1) define the prevalence and timing of their vibrissal replacement, (2) determine the vibrissal regrowth rate and temporal resolution of isotopic data captured along the length of sequentially sampled vibrissae, and (3) explore assumptions regarding their vibrissal growth. Contrary to the previously described asynchronous vibrissal shedding pattern of SES, 71.1% of individuals displayed vibrissal shedding during the annual pelage moult. Furthermore, vibrissal growth ceased once the asymptotic length was reached, and the vibrissae were retained before being replaced. Vibrissae with known growth histories were resampled at multiple known intervals to control for unknown growth starting dates. Vibrissae followed a von Bertalanffy growth function as the growth rate decreased near the asymptotic length. The resolution of the isotopic data obtainable per 2 mm section ranged from 3.5 d at the vibrissal tip to >40 d at the base. Using these defined growth rates and shedding patterns, researchers can prudently apply timestamps to stable isotope values along vibrissae. https://www.researchgate.net/publication/310330776_Vibrissal_growth_parameters_of_southern_elephant_seals_Mirounga_leonina_Obtaining_fine-scale_time-based_stable_isotope_data Sincerely, Nico Lubcker nlubc...@zoology.up.ac.za PhD Zoology Candidate Mammal Research Institute Department of Zoology and Entomology University of Pretoria South Africa - This message and attachments are subject to a disclaimer. Please refer to http://www.it.up.ac.za/documentation/governance/disclaimer/ for full details. / Hierdie boodskap en aanhangsels is aan 'n vrywaringsklousule onderhewig. Volledige besonderhede is by http://www.it.up.ac.za/documentation/governance/disclaimer/ beskikbaar. ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] New article: Juvenile southern elephant seals from Marion Island consume krill: a stable isotope investigation using whisker regrowths
Dear colleagues, My co-authors and I would like to share with you our work recently published in Marine Ecology Progress Series: Lübcker N, Reisinger RR, Oosthuizen WC, de Bruyn PJN, van Tonder A, Pistorius PA, Bester MN. 2017. Low trophic level diet of juvenile southern elephant seals Mirounga leonina from Marion Island: a stable isotope investigation using vibrissal regrowths. Mar Ecol Prog Ser 577: 237250. Article available at https://doi.org/10.3354/meps12240. ABSTRACT: Insight into the trophic ecology of marine predators is vital for understanding their ecosystem role and predicting their responses to environmental change. Juvenile southern elephant seals (SES) Mirounga leonina are considered generalist predators within the Southern Ocean. Although mesopelagic fish and squid dominate their stomach lavage samples, the stable isotope profile captured along the length of sampled vibrissae of young SES at Macquarie Island, southwest Pacific Ocean (54.5° S, 158.9° E) recently emphasized the contribution of crustaceans to their diet (likely Euphausia superba). Herein, we used the stable isotope values of sampled vibrissal regrowths with known growth histories to assess the diet of juvenile SES at Marion Island, southern Indian Ocean (46.8° S, 37.8° E) on a temporally integrated basis. We specifically aimed to quantify the possible contribution of crustaceans to the diet of juvenile SES. Sequentially (chronologically) sampled vibrissal regrowths of 14 juvenile SES produced fine-scale dietary information spanning up to 9 mo. The depleted stable isotope signatures of nitrogen (d15N) (8.5 ± 0.6) and carbon (d13C) (-20.3 ± 0.1) measured during the period of independent foraging suggested the use of a lower trophic level diet within the Polar Frontal Zone. A mixing model predicted that up to 76% of juvenile SES diet comprised crustaceans, consisting of 2 crustacean groups, each contributing 26% (credible interval, CI: 13 - 39%) and 50% (CI: 35 - 64%) to their diets, presumably representing subantarctic krill species. This first utilisation of the isotopic signature captured along the length of vibrissal regrowths confirms the inclusion and importance of crustaceans in the diet of juvenile SES. See (https://www.researchgate.net/project/Low-trophic-level-diet-of-juvenile-southern-elephant-seals-Mirounga-leonina-from-Marion-Island-a-stable-isotope-investigation-using-vibrissal-regrowths/) for more information regarding this project, or (http://www.marionseals.com/) for more information regarding our research group. Sincerely, Nico Lubcker PhD. Zoology Candidate Mammal Research Institute Old Botany Building Room 1.16.5 Department of Zoology and Entomology University of Pretoria Hatfield South Africa 0028 Cell: + 27 72 0370130 Original Message Subject: New article: Vibrissal growth parameters of southern elephant seals Mirounga leonina From:"Nico Lubcker" <nlubc...@zoology.up.ac.za> Date:Thu, January 5, 2017 09:35 To: "marmam@lists.uvic.ca" <marmam@lists.uvic.ca> -- Dear colleagues, My co-authors and I would like to share with you our work recently published in Marine Ecology Progress Series: Lübcker N, Condit R, Beltran RS, de Bruyn PJN, Bester MN. 2016. Vibrissal growth parameters of southern elephant seals Mirounga leonina: obtaining fine-scale, time-based stable isotope data. Marine Ecology Progress Series 559: 243-255. doi: 10.3354/meps11899. Article available at http://www.int-res.com/abstracts/meps/v559/p243-255/ ABSTRACT: Stable isotopes provide a powerful, indirect approach to assess the trophic ecology of individuals on a spatial and temporally integrated basis (especially when combined with telemetry). However, using stable isotopes requires accurate, species-specific quantification of the period of biomolecule deposition in the sampled tissue. Sequentially sampled vibrissae (whiskers) provide a chronology of biogeochemical data, although knowledge of vibrissal growth is required for temporal interpretations. We sampled vibrissae from southern elephant seals Mirounga leonina (hereafter SES) at Marion Island, southern Indian Ocean, to address the following aims: (1) define the prevalence and timing of their vibrissal replacement, (2) determine the vibrissal regrowth rate and temporal resolution of isotopic data captured along the length of sequentially sampled vibrissae, and (3) explore assumptions regarding their vibrissal growth. Contrary to the previously described asynchronous vibrissal shedding pattern of SES, 71.1% of individuals displayed vibrissal shedding during the annual pelage moult. Furthermore, vibrissal growth ceased once the asymptotic length was reached, and the vibrissae were retained before being replaced. Vibrissae with known growth histories were resampled at multiple known intervals to con
[MARMAM] Article. Steroid extraction from whiskers: Publication of novel 'method'
Dear colleagues, We are pleased to announce the publication of the Marion Island Marine Mammal Programme (MIMMP's) latest paper: “What’s in a whisker? High-throughput analysis of twenty-eight C19 and C21 steroids in mammalian whiskers by ultra-performance convergence chromatography-tandem mass spectrometry”. Herein, we developed a novel method to analyze multiple steroids deposited chronologically along the length of seal whiskers. The manuscript describes an accurate quantification method for multiple steroids, measured in a single chromatography step which reduces the cost and time associated with the analyses. The advance of this method can contribute to our understanding of the impact of stress associated with environmental/climate changes that affect the health and survival of organisms, as well as to delineate the reproductive cycles of free-living mammals with cryptic life stages. I trust that the readership of this mailing list will find the manuscript of interest. https://www.sciencedirect.com/science/article/abs/pii/S1570023219316642?fbclid=IwAR0_9tajNPrR9JlBcM_62k1TW6_qp5eIQhv3nVaDfHpF1HPvzBPwPJ73NL4 https://www.researchgate.net/publication/339227340_What's_in_a_whisker_High-throughput_analysis_of_twenty-eight_C19_and_C21_steroids_in_mammalian_whiskers_by_ultra-performance_convergence_chromatography-tandem_mass_spectrometry Sincerely, Nico Lubcker PhD. Zoology Candidate Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria https://www.researchgate.net/profile/Nico_Luebcker marionseals.com/people/ ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] MARMAM submission, New Publication: Fasting affects amino acid nitrogen isotope values: a new tool for identifying nitrogen balance of free-ranging mammals
Dear Marmamers, My co-authors and I are pleased to announce our new publication in *Oecologia*. Lübcker, N., Whiteman, J.P., Millar, R.P. et al. Fasting affects amino acid nitrogen isotope values: a new tool for identifying nitrogen balance of free-ranging mammals. Oecologia (2020). https://doi.org/10.1007/s00442-020-04645-5 Please take care of yourselves and each other during this difficult time. Abstract Changes in the nutritional status of free-ranging animals have a strong influence on individual fitness, yet it remains challenging to monitor longitudinally. Nitrogen (δ15N) and carbon (δ13C) isotope values measured chronologically along the length of metabolically inert keratinous tissues can be used as a nutritional biomarker to retrospectively reconstruct the foraging ecology and eco-physiology of consumers. We quantitatively describe the physiological effects of fasting on amino acid metabolism using sequentially measured bulk tissue and amino acid δ15N values along the length of whiskers sampled from free-ranging juvenile, subadults, adult female, and male southern elephant seals (SES; Mirounga leonina) on Marion Island in the Southern Ocean. For both juveniles and adult females, whisker segments representing fasting had significantly higher bulk tissue δ15N values of 0.6 ± 0.5‰ and 1.3–1.8‰, respectively, in comparison to segments unaffected by fasting. We also found a large increase (2–6‰) in δ15N values for most glucogenic amino acids and a simultaneous depletion (2–3‰) of alanine in segments reflecting fasting, which enabled us to accurately predict (74%) the nutritional status of our model species. We hypothesize that the glucose-alanine cycle is the mechanism driving the observed depletion of alanine δ15N values during fasting. We demonstrated that keratinaceous tissues can be used as a longitudinal nutritional biomarker to detect changes in the nitrogen balance of an individual. Moreover, it is evident that physiological factors have an important influence on tissue δ15N values and can lead to erroneous bulk tissue or amino acid isotope-based reconstructions of foraging habits. https://www.researchgate.net/publication/340684991_Fasting_affects_amino_acid_nitrogen_isotope_values_a_new_tool_for_identifying_nitrogen_balance_of_free-ranging_mammals Thank you Sincerely, Nico Lubcker PhD. Zoology Candidate Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria https://www.researchgate.net/profile/Nico_Luebcker marionseals.com/people/ ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
[MARMAM] MARMAM submission, New Publication: What’s in a whisker? High-throughput analysis of twenty-eight C19 and C21 steroids in mammalian whiskers by ultra-performance convergence chromatography-ta
Dear Marmamers, My co-authors and I are pleased to announce our new publication in *Journal of Chromatography B*. Lübcker N, Bloem LM, du Toit T, Swart P, de Bruyn PN, Swart AC, Millar RP. What’s in a whisker? High-throughput analysis of twenty-eight C19 and C21 steroids in mammalian whiskers by ultra-performance convergence chromatography-tandem mass spectrometry. Journal of Chromatography B. 2020 Mar 15;1141:122028. https://doi.org/10.1016/j.jchromb.2020.122028 Please take care and shout if I can be of assistance. *Highlights* • We developed a high-throughput assay to quantify 28 steroids from single whiskers. •This UPC2-MS/MS method enabled the first quantification of a suite of steroids detectable in mammalian whiskers. •Sensitive and accurate quantification method at reduced cost and time. •Whiskers provides biomatrix for longitudinal steroid hormones monitoring. •Applicable to free-ranging mammals with cryptic life cycles. *Abstract* Obtaining longitudinal endocrinological data from free-ranging animals remains challenging. Steroid hormones can be extracted sequentially from non-invasively sampled biologically inert keratinous tissues, such as feathers, nails, hair and whiskers. However, uncertainty regarding the type and levels of steroids incorporated into such tissues complicates their utility in wildlife studies. Here, we developed a novel, comprehensive method to analyze fourteen C19 and fourteen C21 steroids deposited chronologically along the length of seal whiskers in a single, 6-minute chromatographic step, using ultra-performance convergence chromatography-tandem mass spectrometry. The limits of detection and quantification ranged from 0.01 to 2 ng/mL and from 0.1 to 10 ng/mL, respectively. The accuracy and precision were within acceptable limits for steroids at concentrations ≥2 ng/mL. The recovery (mean = 107.5% at 200 ng/mL), matrix effect and process efficiency of steroids evaluated, using blanked whisker matrix samples, were acceptable. The method was applied to the analysis of steroid hormone levels in adult female whisker segments obtained from southern elephant seals (Mirounga leonina), n = 10, and two fur seal species, Antarctic fur seals (Arctocephalus gazella; n = 5) and subantarctic fur seals (Arctocephalus tropicalis; n = 5), sampled between 2012 and 2017. In the whisker subsamples analyzed (n = 71), the median concentration of steroid hormones detected above the LOQ ranged from 2.0 to 273.7 pg/mg. This was the first extraction of multiple C19 and C21 steroids, including their C11-oxy metabolites, from the whiskers of mammals. Measuring hormones sequentially along the whisker lengths can contribute to our understanding of the impact of stress associated with environmental/climate changes that affect the health, survival of organisms, as well as to delineate the reproductive cycles of free-living mammals with cryptic life stages. https://www.researchgate.net/publication/339227340_What's_in_a_whisker_High-throughput_analysis_of_twenty-eight_C19_and_C21_steroids_in_mammalian_whiskers_by_ultra-performance_convergence_chromatography-tandem_mass_spectrometry Thank you Sincerely, Nico Lubcker PhD. Zoology Candidate Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria https://www.researchgate.net/profile/Nico_Luebcker marionseals.com/people/ ___ MARMAM mailing list MARMAM@lists.uvic.ca https://lists.uvic.ca/mailman/listinfo/marmam
