Life history studies of the southern elephant seal population at Marion Island

Holistic studies of mammalian life history factors and their consequences on population demography require an intensive, multifaceted field methodology and effort over long temporal scales. A 25-year longitudinal mark-recapture experiment on southern elephant seals, Mirounga leonina, at Subantarctic Marion Island provide such a foundation for demographic analyses and relevant methodology advancement. Two gaps in the methodology related to life history and population demographic research are, the absence of large samples of known mass individuals, and an inability to identify mother-pup relatedness. A novel three-dimensional photogrammetric technique is designed here that allows for mass estimation of large samples of southern elephant seals in the field. An effective temporary marking technique for unweaned pups is implemented that allows for identification of large samples of pups with known mothers prior to the maternal bond being severed at weaning. These known pups can then be marked with more robust tags and relatedness information is preserved long-term. Thus, mass estimates can now be applied as covariates in modelling analyses to address questions of, for example, maternal investment, kinship associated behaviour, and the consequences thereof on survival and reproductive parameters. The state change in the Marion Island southern elephant seal population from decrease to stabilisation/increase is shown to have resulted from improved survivorship in both juvenile and adult female age classes. Male seals of all ages did not indicate improved survivorship following the period of decline. The inflexion in survivorship is identified as 1994, whence improved survivorship of juvenile seals preceded that of young adult females. This inflexion in survivorship is postulated to have resulted in a population trend inflexion around 1998. Female southern elephant seals do not show evidence of actuarial senescence, but reproductive senescence is apparent after 12 years of age. A longterm reproductive cost (reduced breeding effort) is associated with early primiparity (age three) as compared with later primiparity (4- 5- or 6-year-old). The mean proportion of 3-year-old breeders has not increased after 1994 as has been hypothesized in previous studies. Contrary to previous assumptions, females do not as a rule breed every year. Annually interrupted breeding efforts are more common than consecutive breeding efforts. No difference in the proportions of interrupted versus uninterrupted breeding efforts was identified between periods of population decline and stabilisation/increase. Longevity as predicted by survival estimates exceeds the observed frequencies. This study provides unique longevity and fertility schedules for the species. The improved survivorship, reproductive senescence and breeding schedules of female southern elephant seals in this population provide groundwork for reevaluation of previous studies and their conclusions. The addition of relatedness and body condition information will allow for sophisticated multistate modelling of population demography in future studies. However, analytical procedures and techniques employed need to be meticulously designed and thoroughly thought through to avoid mis-interpretation of biological data. In addition to a multistate single species analytical approach, the importance of an ecosystem approach to species population demographic studies is highlighted through the augmenting of data on relevant potential drivers of population change, such as killer whales, Orcinus orca.Thesis (PhD)--University of Pretoria, 2009.Zoology and Entomologyunrestricte

Riding shutdowns in developing world

The recent US government shutdown hit researchers in the Antarctic particularly hard (G. E. Hofmann Nature 502, 431–432; 2013). But spare a thought for the feats of endurance shown by scientists from the developing world, who continue working in such harsh environments while contending with chronically unpredictable political factors in their own countries.http://www.nature.com/nature/index.htmlhb2014ab201

Pinniped entanglement in oceanic plastic pollution : a global review

Oceanic plastic pollution is a growing worldwide environmental concern, endangering numerous marine species. Pinnipeds are particularly susceptible to entanglement, especially in abandoned, lost or discarded fishing gear and packaging straps. We searched three international databases to compile a comprehensive review of all reported pinniped entanglements over the last 40 years, with the aim to identify areas of concern and foci for mitigation. The majority of published records of entanglement emanate from North America and Oceania and are focused on a few populous species (notably, Zalophus californianus and Arctocephalus gazella). Reporting bias, skewed research effort and incomplete understanding of plastic pollution and pinniped abundance overlap, combine to cloud our understanding of the entanglement problem. Broader geographical effort in entanglement data collection, reporting of such data, and improved quantification of the proportions of populations, sexes and ages that are most susceptible, will aid our efforts to pinpoint priority mitigation measures.http://www.elsevier.com/locate/marpolbul2020-08-01hj2019Mammal Research InstituteZoology and Entomolog

Simplifying photogrammetric analysis for assessment of large mammal mass : automated targeting and 3D model building

Close range photogrammetry has increasingly diverse practical application within the biological sciences. Its use in large mammal research for size and/or mass estimation has proven extremely beneficial. Recent photogrammetric technique advancements have improved its applicability in the field, although some analytical components remain time consuming. The use of automated coded targets, associated with commercially available software, was evaluated to simplify photogrammetric analysis without compromising its practicality. The effects of variable target size and shape, lighting conditions, number of photographs, photograph target coverage and project processing time were assessed. Augmenting a published photogrammetric field technique by including coded targets greatly reduced analysis time. The simplified method is attractive for use by a wider range of both specialist and non-specialist users for applications within the animal photogrammetry field.University of Pretoria provided financial support for this research through its Research Development Program.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1477-97302016-06-30hb201

Australia : no price on cutting fire risk

No abstract available.http://www.nature.com/nature/index.htmlab201

Can The Carbon and Nitrogen Isotope Values of Offspring be Used as a Proxy for Their Mother\u27s Diet? Using Foetal Physiology to Interpret Bulk Tissue and Amino Acid \u3ci\u3eδ\u3c/i\u3e\u3csup\u3e15\u3c/sup\u3eN Values

The measurement of bulk tissue nitrogen (δ15N) and carbon isotope values (δ13C) chronologically along biologically inert tissues sampled from offspring can provide a longitudinal record of their mothers\u27 foraging habits. This study tested the important assumption that mother-offspring stable isotope values are positively and linearly correlated. In addition, any change in the mother-offspring bulk tissues and individual amino acids that occurred during gestation was investigated. Whiskers sampled from southern elephant seal pups (Mirounga leonina) and temporally overlapping whiskers from their mothers were analyzed. This included n = 1895 chronologically subsampled whisker segments for bulk tissue δ15N and δ13C in total and n = 20 whisker segments for amino acid δ15N values, sampled from recently weaned pups (n = 17), juvenile southern elephant seals (SES) \u3c 2 years old (n = 23) and adult female SES (n = 17), which included nine mother-offspring pairs. In contrast to previous studies, the mother-offspring pairs were not in isotopic equilibrium or linearly correlated during gestation: the Δ15N and Δ13C mother-offspring offsets increased by 0.8 and 1.2‰, respectively, during gestation. The foetal bulk δ15N values were 1.7 ± 0.5‰ (0.9-2.7‰) higher than mothers\u27 δ15N values before birth, while the foetal δ13C increased by ~1.7‰ during gestation and were 1.0 ± 0.5‰ (0.0-1.9‰) higher than their mothers\u27 δ13C at the end of pregnancy. The mother-offspring serine and glycine Δ15N differed by ~4.3‰, while the foetal alanine δ15N values were 1.4‰ lower than that of their mothers during the third trimester of pregnancy. The observed mother-offspring δ15N differences are likely explained by shuttling of glutamate-glutamine and glycine-serine amongst skeletal muscle, liver, placenta and foetal tissue. Foetal development relies primarily on remobilized endogenous maternal proteinaceous sources. Researchers should consider foetal physiology when using offspring bulk tissue isotope values as biomarkers for the mother\u27s isotopic composition as part of monitoring programmes

An open access geospatial database for the sub-Antarctic Prince Edward Islands

Researchers of projects at the sub-Antarctic Prince Edward Islands are increasingly considering geospatial data as an essential component in answering scientific questions. A need exists for high-resolution geospatial data in both multi- and transdisciplinary research to better analyse fine-scale biotic–abiotic interactions of the Islands’ landscape and ecosystems within the context of climate change and the impacts of invasive species. However, much of the geospatial data that currently exist have limitations in spatial coverage and/or resolution, are outdated, or are not readily available. To address these issues, we present an online geospatial database for the Prince Edward Islands (both islands) produced from a high-resolution digital surface model and satellite imagery. This database contains vector files, raster data sets, and maps of topographical and hydrological parameters. It is freely available to download from Figshare – an open access data repository. We encourage the South African polar science community to make use of similar platforms for improved data sharing practices. Significance: A topographical and hydrological geospatial database – produced from a 1 m x 1 m digital surface model of the Prince Edward Islands – is provided. These fine-scale geospatial data allow for a more comprehensive assessment of biotic–abiotic interactions at an island scale. Also included are locality maps specifying place names and established long-term marine mammal monitoring beaches and coastal zones for improved cross-referencing. The dataset is downloadable from an open access data repository and intended to promote open science and data sharing practices

Multi-state mark-recapture models as a novel approach to estimate factors affecting attendance patterns of lactating subantarctic fur seals from Marion Island

Observer-based studies often underestimate key ecological parameters. Here a fresh approach was used to analyse six years (2006–11) of attendance cycles to estimate foraging trip lengths of a lactating flipper-tagged otariid: subantarctic fur seals at Marion Island. Multi-state mark-recapture models were used to calculate detection failures of females, correct estimates accordingly, and investigate the effects of year, season, pup sex and the presence of a telemetry device on attendance cycle parameters. There were no differences between corrected and uncorrected attendance data. This is attributed to the high capture probability across all seasons (range: 83–98%). This illustrates that observer-based studies are useful to augment telemetry studies. Only season and pup sex had a significant impact on female provisioning rates. In winter, foraging trip durations were longer (t-value = 25.22, P <0.0001) and attendance durations shorter (t-value = -2.15, P = 0.01) than during summer. Females with female pups spent a higher proportion of their time on land (χ2 = 6.6, P < 0.05). Male pups have higher growth demands and are larger which suggests they can deplete female milk-stores faster.Department of Science and Technology,through the National Research Foundation (NRF), in support of the Marion Island Marine Mammal Programme (MIMMP) of the MRI.http://journals.cambridge.org/action/displayJournal?jid=ANS2015-12-31hb201

Shower water usage in Kruger National Park tourist accommodation : effectiveness of technology and information intervention to reduce use

Human freshwater consumption continues to be a growing global concern. Research and implementation of interventions on multiple fronts are required to safeguard this critical resource. Household water consumption is a significant contributor to overall freshwater use. Such indoor water use in nature-based tourism presents a challenge to this industry, but also provides opportunities to influence human behaviour and experimenting with, and mainstreaming, new technologies promoting water conservation and sustainability. Here we assess interventions to one significant source of water use (showers) in tourist accommodation in a popular nature-based tourism destination, the Kruger National Park, South Africa. Control trials utilizing information interventions (to induce behavioural change), and a novel shower technology, are implemented to identify water saving opportunities. We show that technological intervention (installation of Triton Xerophyte®) results in ∼30% overall water saving as compared to control showers. Adding water-saving infographics slightly enhances this saving, but is shown to have limited success when implemented in isolation (i.e. without the technology). In addition, we show how shower duration and water usage is related to ambient temperature, with the Triton Xerophyte® resulting in increasing water savings under cooler ambient conditions (up to ∼50% water reduction for ambient temperatures <5 °C). Encouragingly, visitors to this national park are shown to use less shower water and shower for shorter, even in control units, as compared to the general public, suggesting that these nature-based tourists may already be more mindful of water usage. Nature-based tourism agencies have a responsibility to promote water saving behaviour, and implementing technology and providing information and awareness in aid thereof may act as a catalyst for broader water-conservation in society.https://pubs.rsc.org/en/journals/journal/ewhj2023Mammal Research InstituteZoology and Entomolog

Spatial variation in female southern elephant seal mass change assessed by an accurate non-invasive photogrammetry method

Physically weighing large marine mammals sequentially over time has presented researchers with a logistical challenge and has severely limited sample sizes. Using a well-established photogrammetry method we developed a simple mathematical method to calculate accurate mass measurements at specific stages in the life cycle of a top marine predator. Female southern elephant seals (n523) at Marion Island were sampled sequentially using photogrammetry and three-dimensional models (based on each photogrammetry project) were built for estimation of body mass. Simple equations were applied to obtain mass at critical instances in their life cycle. Marion Island elephant seal mass data was compared to data obtained from physically weighed elephant seals from King George, South Georgia and Macquarie islands. Females from Marion Island are smaller, but their percentage lactation mass loss is similar to females from these other populations. The similarity of percentage mass loss during lactation between different female populations illustrates the accuracy and practicality of the photogrammetric method over a temporal scale. Photogrammetric mass estimation can be used alongside datasets of physically weighed animals and can greatly benefit ecology and life history studies.http://journals.cambridge.orgam201