Adiposity and Fat Metabolism During Combined Fasting and Lactation in Elephant Seals

Animals that fast depend on mobilizing lipid stores to power metabolism. Northern elephant seals (Mirounga angustirostris) incorporate extended fasting into several life-history stages: development, molting, breeding and lactation. The physiological processes enabling fasting and lactation are important in the context of the ecology and life history of elephant seals. The rare combination of fasting and lactation depends on the efficient mobilization of lipid from adipose stores and its direction into milk production. The mother elephant seal must ration her finite body stores to power maintenance metabolism, as well as to produce large quantities of lipid and protein rich milk. Lipid from body stores must first be mobilized; the action of lipolytic enzymes and hormones stimulate the release of fatty acids into the bloodstream. Biochemical processes affect the release of specific fatty acids in a predictable manner, and the pattern of release from lipid stores is closely reflected in the fatty acid content of the milk lipid. The content of the milk may have substantial developmental, thermoregulatory and metabolic consequences for the pup. The lactation and developmental patterns found in elephant seals are similar in some respects to those of other mammals; however, even within the limited number of mammals that simultaneously fast and lactate, there are important differences in the mechanisms that regulate lipid mobilization and milk lipid content. Although ungulates and humans do not fast during lactation, there are interesting comparisons to these groups regarding lipid mobilization and milk lipid content patterns

Mid-winter temperatures, not spring temperatures, predict breeding phenology in the European starling Sturnus vulgaris

In many species, empirical data suggest that temperatures less than 1 month before breeding strongly influence laying date, consistent with predictions that short lag times between cue and response are more reliable, decreasing the chance of mismatch with prey. Here we show in European starlings (Sturnus vulgaris) that mid-winter temperature ca 50–90 days before laying (8 January–22 February) strongly (r2 = 0.89) predicts annual variation in laying date. Mid-winter temperature also correlated highly with relative clutch size: birds laid later, but laid larger clutches, in years when mid-winter temperatures were lower. Despite a high degree of breeding synchrony (mean laying date 5–13 April = ±4 days; 80% of nests laid within 4.8 days within year), European starlings show strong date-dependent variation in clutch size and productivity, but this appears to be mediated by a different temporal mechanism for integration of supplemental cue (temperature) information. We suggest the relationship between mid-winter temperature and breeding phenology might be indirect with both components correlating with a third factor: temperature-dependent development of the starling\u27s insect (tipulid) prey. Mid-winter temperatures might set the trajectory of growth and final biomass of tipulid larvae, with this temperature cue providing starlings with information on breeding season prey availability (though exactly how remains unknown)

Mid-winter temperatures, not spring temperatures, predict breeding phenology in the European starling Sturnus vulgaris

In many species, empirical data suggest that temperatures less than 1 month before breeding strongly influence laying date, consistent with predictions that short lag times between cue and response are more reliable, decreasing the chance of mismatch with prey. Here we show in European starlings (Sturnus vulgaris) that mid-winter temperature ca 50–90 days before laying (8 January–22 February) strongly (r2 = 0.89) predicts annual variation in laying date. Mid-winter temperature also correlated highly with relative clutch size: birds laid later, but laid larger clutches, in years when mid-winter temperatures were lower. Despite a high degree of breeding synchrony (mean laying date 5–13 April = ±4 days; 80% of nests laid within 4.8 days within year), European starlings show strong date-dependent variation in clutch size and productivity, but this appears to be mediated by a different temporal mechanism for integration of supplemental cue (temperature) information. We suggest the relationship between mid-winter temperature and breeding phenology might be indirect with both components correlating with a third factor: temperature-dependent development of the starling\u27s insect (tipulid) prey. Mid-winter temperatures might set the trajectory of growth and final biomass of tipulid larvae, with this temperature cue providing starlings with information on breeding season prey availability (though exactly how remains unknown)

Fine-scale foraging behaviour of female northern elephant seals during the entire post-breeding migration

第32回極域生物シンポジウムポスター発

Deep-sea foraging behavior of elephant seals: use of different foraging strategy from deep diving toothed whales

第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月26日（月） 国立極地研究所 ３階ラウン

Foraging Behavior and Success of a Mesopelagic Predator in the Northeast Pacific Ocean: Insights from a Data-Rich Species, the Northern Elephant Seal

The mesopelagic zone of the northeast Pacific Ocean is an important foraging habitat for many predators, yet few studies have addressed the factors driving basin-scale predator distributions or inter-annual variability in foraging and breeding success. Understanding these processes is critical to reveal how conditions at sea cascade to population-level effects. To begin addressing these challenging questions, we collected diving, tracking, foraging success, and natality data for 297 adult female northern elephant seal migrations from 2004 to 2010. During the longer post-molting migration, individual energy gain rates were significant predictors of pregnancy. At sea, seals focused their foraging effort along a narrow band corresponding to the boundary between the sub-arctic and sub-tropical gyres. In contrast to shallow-diving predators, elephant seals target the gyre-gyre boundary throughout the year rather than follow the southward winter migration of surface features, such as the Transition Zone Chlorophyll Front. We also assessed the impact of added transit costs by studying seals at a colony near the southern extent of the species’ range, 1,150 km to the south. A much larger proportion of seals foraged locally, implying plasticity in foraging strategies and possibly prey type. While these findings are derived from a single species, the results may provide insight to the foraging patterns of many other meso-pelagic predators in the northeast Pacific Ocean

Mosaic: A Satellite Constellation to Enable Groundbreaking Mars Climate System Science and Prepare for Human Exploration

The Martian climate system has been revealed to rival the complexity of Earth\u27s. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars\u27 diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars\u27 plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions

SNAPSHOT USA 2019 : a coordinated national camera trap survey of the United States

This article is protected by copyright. All rights reserved.With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14-week period (17 August - 24 November of 2019). We sampled wildlife at 1509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian's eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the USA. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban-wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot-usa, as well as future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species-specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.Publisher PDFPeer reviewe

REGULATION OF LIPID METABOLISM AND MILK LIPID CONTENT IN NORTHERN ELEPHANT SEALS

Animals that fast depend on mobilizing lipid stores to power metabolism. Northern elephant seals (Mirounga angustirostris) incorporate extended fasting into several life history stages: post weaning development, molting, breeding and lactation. The mobilization and subsequent utilization of lipid stores could have consequences for the current and future survival and reproduction. Despite the importance of lipid metabolism to elephant seals little is known about the regulation of lipid mobilization and the physiological drivers of milk lipid content. This thesis focused on three aspects of lipid reserve rationing in adult female elephant seals. Chapter 1 investigated the mobilization of specific fatty acids from blubber and the partitioning of fatty acids between maternal metabolism and milk synthesis in northern elephant seals. In Chapter 2 I examined the hormonal regulation of lipid mobilization and milk lipid content and in Chapter 3 I investigated the activity of lipolytic enzymes and their relationship to milk lipid content. To examine these topics, fatty acid signatures were compared between the blubber and milk in early and late lactation. Additionally, lipid metabolites and milk lipid content were assessed in relationship to circulating levels of growth hormone, cortisol and insulin. Milk lipid content was also assessed relative to the activity of two lipolytic enzymes in theblubber, hormone sensitive lipase and adipose triglyceride lipase. Results indicate that elephant seals mobilize specific fatty acids in a similar fashion to many other mammals and birds. Additionally, the milk is enriched in long chain monounsaturated fatty acids in late lactation. Mass and adiposity were significant (p<0.05) predictors of milk lipid content. Other important predictors of milk lipid content were circulating non-esterified fatty acid and triglyceride levels, cortisol and insulin. Unexpectedly I found that growth hormone was uncoupled from both circulating lipid metabolite concentrations and milk lipid content. Hormone sensitive lipase was found to be negligible in northern elephant seal blubber, another unexpected result. Adipose triglyceride lipase protein content was higher in late lactation relative to early lactation, but activity levels were stable across lactation and unrelated to milk lipid content. Molting seals regulate lipolysis differently than lactating seals, with insulin mediating an even greater release of lipid stores in lactating females, to facilitate availability for milk production. There was a more positive relationship between triglycerides and milk lipid content than expected, but there was strong evidence supporting the hypothesis that milk lipid content is regulated at the level of mobilization of milk precursors from lipid stores. Contrary to previous hypotheses, hormone sensitive lipase was not the primary lipolytic enzyme and adipose triglyceride lipase assumed a more prominent role in lipid mobilization. Additionally, the specific regulation of these enzymes may differ among age classes and species. Despite their phenomenal lipid mobilization ability, mechanisms of thelipid mobilization of specific fatty acids are conserved among northern elephant seals and other mammals. Conversely, the hormonal and enzymatic regulation of lipid mobilization exhibit differences between elephant seals and other mammals