Juvenile Density Research Articles

Socially cued anticipatory adjustment of female signalling effort in a moth.

Juvenile population density has profound effects on subsequent adult development, morphology and reproductive investment. Yet, little is known about how the juvenile social environment affects adult investment into chemical sexual signalling. Male gumleaf skeletonizer moths, Uraba lugens, facultatively increase investment into antennae (pheromone receiving structures) when reared at low juvenile population densities, but whether there is comparable adjustment by females into pheromone investment is not known. We investigate how juvenile population density influences the 'calling' (pheromone-releasing) behaviour of females and the attractiveness of their pheromones. Female U. lugens adjust their calling behaviour in response to socio-sexual cues: adult females reared in high juvenile population densities called earlier and for longer than those from low juvenile densities. Juvenile density also affected female pheromonal attractiveness: Y-maze olfactometer assays revealed that males prefer pheromones produced by females reared at high juvenile densities. This strategic investment in calling behaviour by females, based on juvenile cues that anticipate the future socio-sexual environment, likely reflects a response to avoid mating failure through competition with neighbouring signallers.

Individual-based model of population dynamics in a sea urchin of the Kerguelen Plateau (Southern Ocean), Abatus cordatus, under changing environmental conditions

The Kerguelen Islands are part of the French Southern Territories, located at the limit of the Indian and Southern oceans. They are highly impacted by climate change, and coastal marine areas are particularly at risk. Assessing the responses of species and populations to environmental change is challenging in such areas for which ecological modelling can constitute a helpful approach. In the present work, a DEB-IBM model (Dynamic Energy Budget – Individual-Based Model) was generated to simulate and predict population dynamics in an endemic and common benthic species of shallow marine habitats of the Kerguelen Islands, the sea urchin Abatus cordatus. The model relies on a dynamic energy budget model (DEB) developed at the individual level. Upscaled to an individual-based population model (IBM), it then enables to model population dynamics through time as a result of individual physiological responses to environmental variations. The model was successfully built for a reference site to simulate the response of populations to variations in food resources and temperature. Then, it was implemented to model population dynamics at other sites and for the different IPCC climate change scenarios RCP 2.6 and 8.5. Under present-day conditions, models predict a more determinant effect of food resources on population densities, and on juvenile densities in particular, relative to temperature. In contrast, simulations predict a sharp decline in population densities under conditions of IPCC scenarios RCP 2.6 and RCP 8.5 with a determinant effect of water warming leading to the extinction of most vulnerable populations after a 30-year simulation time due to high mortality levels associated with peaks of high temperatures. Such a dynamic model is here applied for the first time to a Southern Ocean benthic and brooding species and offers interesting prospects for Antarctic and sub-Antarctic biodiversity research. It could constitute a useful tool to support conservation studies in these remote regions where access and bio-monitoring represent challenging issues.

Juvenile scleractinian assemblage and its association with adults and benthos at shallow and upper mesophotic depths in fringing and atoll reefs in the Philippines

The juvenile stage is a critical part of a scleractinian’s life history as it is when they are highly vulnerable to various post-settlement mortality processes, which influence the structure of adult scleractinian assemblages. Although numerous studies have been done to understand dynamics of juvenile assemblages at shallow water reefs (SWRs), similar studies on deeper and less explored reefs, such as mesophotic coral ecosystems (MCEs) remain limited. Using diver-based photo-quadrat method, we aimed to examine how juvenile scleractinian assemblages vary from SWRs (shallow: 3 to 10 m and middle: 10 to 20 m) to upper MCEs (deep: 30 to 40 m) in the fringing and atoll reefs in the Apo Reef Natural Park, Philippines. We also aimed to understand the potential association of juvenile scleractinian densities with adult scleractinian densities and benthic cover. A total of 12 families were recorded for both juveniles and adults with Poritidae being the most abundant, followed by Pocilloporidae and Acroporidae (and Merulinidae for juveniles only). Juvenile densities (ranging from 14 to 36 individuals/m2) varied among depth zone and reef type interactions and had a bimodal distribution, with the middle zone having the lowest density compared to the shallow and deep zones. Juvenile densities were correlated to benthic cover, particularly to high algal cover in the middle zone and availability of bare hard substrate in the shallow zone. Adult densities were also correlated with juvenile densities, but not commonly in the middle zone, emphasizing that it is only one of the many variables that contribute to juvenile assemblages. This study is the first to document juvenile scleractinian assemblages, how they vary from SWRs to MCEs in the Philippines and the Coral Triangle, and demonstrates the importance of benthos and adult brood stock in shaping juvenile scleractinian assemblages across depth zones.

The Impact of Hydropeaking on Juvenile Brown Trout (Salmo trutta) in a Norwegian Regulated River

The Norwegian electrical energy supply system is based on hydropower. The now deregulated energy market has led to increased use of hydropeaking production, leading to greater fluctuations in discharge and water levels below hydropower stations. The power station HOL 1, with an outlet to the Storåne River, is a large hydropeaking facility. With over 300 rapid flow increases and decreases per year since 2012, it is a river subjected to frequent hydropeaking. To quantify the stranding risk downstream of the power plant, the effect of a series of different turbine shutdown scenarios was simulated in an earlier study. The residual flow of 6 m3·s−1 and a full production of 66 m3·s−1 were considered as the baselines for the calculation of dewatered areas. A three-year study of juvenile fish density both upstream as a reference and downstream of the power plant was undertaken. There were very low densities or even an absence of brown trout (Salmo trutta) older than young-of-the-year (YoY) below the outlet of the power station, despite high densities of YoY in previous years. This is probably due to the large and rapid changes in flow below the power station. Hydropeaking has less impact on the earliest life stages of brown trout during spring and summer, as well as on spawning and egg development during winter. This is attributed spawning in late autumn occurring at a low flow seldom reached during hydropeaking. The high survival of YoY during the first summer and early autumn is likely due to a lower frequency of hydropeaking and higher residual flows, leaving a larger wetted area.

Testing the ecosystem service cascade framework for Atlantic salmon

Aligning nature protection with human well-being for the UN Sustainable Development Goals implies that conservation monitoring should indicate the sustainability of ecosystem services (ES). Here we test the value of the ES cascade framework using national, multi-decadal data for an iconic freshwater fish, the Atlantic salmon Salmo salar. For the first time, we assemble all long-term monitoring data for England and Wales along the ES cascade for this species from resource to benefit: juvenile density to measure the biological resource, returning adult numbers to measure potential ES use, and rod catches and angling effort as measures of actual ES use. We aimed to understand how the ES cascade framework reconciled conservation with ES sustainability targets.Only some linkages along the ES cascade could be evidenced: in catchments where juveniles declined, rod catches also generally decreased, but angling effort declined everywhere irrespective of the biological resource trends. We suggest that i) programmes focused on juvenile monitoring provide an early-warning system for ES provision as well as nature conservation, ii) the ES cascade framework can reconcile nature conservation and ES sustainability if monitoring efforts link biological resources fully to the ES, and ES monitoring explicitly relates biological resources to human use.

Spatiotemporal changes in juvenile lake sturgeon abundance in a large river

Monitoring trends in a long-lived species such as lake sturgeon (Acipenser fulvescens) has it challenges. Targeting the correct life stage to monitor can provide different and contrasting results. Early life stages experience high variable mortality and are often not a good predictor of population trend. Juvenile lake sturgeon (i.e., 5–10 years) experience high survival and could be a good life stage to monitor for assessing population trends. A structured, randomized gillnetting program, Broad-scale Monitoring, which was selective to juvenile lake sturgeon, was conducted over three cycles (i.e., 5 + years apart) in three contiguous Ottawa River reaches supporting lake sturgeon. In this study, we assessed spatiotemporal changes in juvenile lake sturgeon abundance among cycles, among and within the three river reaches. Density rasters based on catch records of lake sturgeon spatially were created using multilevel B-splines. Spatial differences in abundance among cycles was determined by obtaining the difference between the rasters. Three cycles of Broad-scale Monitoring sampled 334 lake sturgeon at a mean CPUE of 0.90 (0.12 SE) sturgeon • gang−1 and a mean total length 673 mm (115 SD) from all three reaches. The relative abundance of juvenile lake sturgeon did not significantly vary among sample cycles, however, CPUE varied within reaches among cycles. There was a spatiotemporal change in density with a decrease in the lowest reach whereas juvenile lake sturgeon density increased the most in the upper reach. The approach used in this study has the potential to monitor spatiotemporal changes in juvenile lake sturgeon abundance populations and may prove effective when assessing rehabilitation or fisheries management efforts.

Nematode populations as affected by residue and water management in a long-term wheat-soybean double-crop system in eastern Arkansas

Soybeans (Glycine max L.) are one of the major row crops in the United States, particularly in Arkansas. The soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is one of the most damaging pests that can cause major economic losses in soybeans. Little is known concerning the combined effects of tillage [conventional tillage (CT) and no tillage (NT)], water management (irrigation and non-irrigation), residue burning (burn and no burn), and wheat residue level (high and low) on nematodes. The objective of this study was to evaluate the effects of the combination of agronomic practices (tillage, water management, burning, and residue level) on natural nematode population densities and change over the growing season in a long-term wheat (Triticum aestivum L.)-soybean rotation on a silt-loam soil in Arkansas. A suite of 10 nematode genera were measured in the top 10 cm in July, August, and October in 2017 and 2018. Averaged across all other treatment factors, SCN egg concentration was 17.9 times greater at the end of the growing season in October than in July and August. The SCN second-stage juvenile (J2) population densities were 3.4 times greater in the CT-burn than in the CT-no-burn and NT-burn treatment combinations. In contrast to under CT, SCN J2 population densities were 3.8 times greater in the NT-no-burn than under the NT-burn treatment combinations. Lance, lesion, spiral, and stunt nematode population densities were also affected by various field treatment combinations. Traditional (i.e., tillage, residue burning, and irrigation) and alternative (i.e., non-tillage, no burning, and dryland) wheat-soybean management practices can influence nematode population densities even in non-problematic fields, thus potentially affecting long-term strategies to maximize soybean profitability.

Coastal wetland restoration improves habitat for juvenile sportfish in Tampa Bay, Florida, U.S.A.

Increasing human populations and urban development have led to losses of estuarine habitats for fish and wildlife. Where resource managers are restoring coastal wetlands, in addition to meeting goals related to hydrologic connectivity, biodiversity, and recreational opportunities, efforts are being made to provide habitat that is suitable for juvenile sportfish. An 18-month study was conducted to compare juvenile sportfish use of natural, restored, and impacted sites along Tampa Bay, Florida, shorelines. Juvenile sportfish densities at restored sites were broadly comparable to natural sites and greater than at impacted sites. However, site-specific differences in sportfish use did occur within site types. For example, one restored site had significantly higher densities of red drum Sciaenops ocellatus than any other site, while black drum Pogonias cromis were found exclusively at another restored site. To evaluate whether the restored sites are providing suitable habitat for juvenile fish, we assessed growth (estimated from counts of daily rings on otoliths) and condition (determined by lipid analyses) of juvenile common snook Centropomus undecimalis, an archetypal coastal wetland-dependent species. Growth (0.43–0.56 mm SL/day) and condition (4.6–6.1% lipid of dry weight) exhibited only site-specific differences and did not vary among natural, restored, and impacted site types. Although mortality rates of juvenile sportfish were not determined, use of a 40-m seine found that densities of potential piscine predators in these coastal wetlands were relatively low compared to published studies of open estuarine shorelines. The restoration and creation of coastal wetlands in Tampa Bay provides improved habitat for juvenile sportfish.

Alternative migratory strategies are widespread in subyearling Chinook salmon

AbstractVariation in life history traits within and across species is known to reflect adaptations to different environmental drivers through a diversity of mechanisms. Trait variation can also help buffer species and populations against extinction in fluctuating environments and against anthropogenic disturbances. Here, we examine the distribution and drivers of Ocean‐type Chinook salmon (Oncorhynchus tschawytscha) juvenile migratory life histories. We defined alternative migratory strategies according to whether individuals reared in the stream (natal rearing) or left shortly after hatching to rear elsewhere (non‐natal rearing). We then evaluated the frequency of migratory strategies across 16 populations with time series extending up to 25 years and evaluated the environmental variables that influenced variation in migration strategy. We found bimodal migration patterns and abrupt transitions in migrant sizes across all populations, supporting the widespread nature of alternative migratory strategies. Additionally, we found that the amount of freshwater rearing habitat available to juveniles, relative juvenile density and spring flow patterns significantly influenced the overall migration pattern for populations. Smaller streams and higher conspecific densities generally produced more non‐natal rearing migrants and larger streams and lower conspecific densities producing more natal rearing migrants. Our results shed light on previously unexplored patterns of juvenile migratory strategies and encourage broader consideration for how current conservation actions perform at protecting juvenile migratory diversity.

Spatio-temporal patterns in juvenile habitat for 13 groundfishes in the California Current Ecosystem.

Identifying juvenile habitats is critical for understanding a species’ ecology and for focusing spatial fishery management by defining references like essential fish habitat (EFH). Here, we used vector autoregressive spatio-temporal models (VAST) to delineate spatial and temporal patterns in juvenile density for 13 commercially important species of groundfishes off the US west coast. In particular, we identified hotspots with high juvenile density. Three qualitative patterns of distribution and abundance emerged. First, Dover sole Microstomus pacificus, Pacific grenadier Coryphaenoides acrolepis, shortspine thornyhead Sebastolobus alascanus, and splitnose rockfish Sebastes diploproa had distinct, spatially-limited hotspots that were spatially consistent through time. Next, Pacific hake Merluccius productus and darkblotched rockfish Sebastes crameri had distinct, spatially limited hotspots, but the location of these hotspots varied through time. Finally, arrowtooth flounder Atheresthes stomias, English sole Parophrys vetulus, sablefish Anoplopoma fimbria, Pacific grenadier Coryphaenoides acrolepis, lingcod Ophiodon elongatus, longspine thornyhead Sebastolobus altivelis, petrale sole Eopsetta jordani, and Pacific sanddab Citharichthys sordidus had large hotspots that spanned a broad latitudinal range. These habitats represent potential, if not likely, nursery areas, the location of which will inform spatial management.

Juvenile (YOY) Black Sea Bass Density on Crepidula Reef Versus Sand/Sponge Habitat in Upper Buzzards Bay, Massachusetts

The black sea bass Centropristis striata population of the Northwest Atlantic has been expanding over the past decade throughout its northern extent in Massachusetts waters. As abundance has increased in the coastal waters of Massachusetts, valuable commercial and recreational fisheries have developed. Relatively little is known about the habitat requirements for black sea bass at different life stages in Massachusetts waters.

Topography and fire legacies drive variable post-fire juvenile conifer regeneration in eastern Oregon, USA

Increasingly frequent large wildfires in the western US raise questions about the effects of climate and site-level factors on forest ecosystem resilience. This study presents findings from seedling and sapling surveys conducted across 179 sites 15–21 years post-fire in eastern Oregon’s Blue Mountain ecoregion. We found wide variation in conifer seedling and sapling densities across low, medium and high burn severity sites in the eight fires surveyed. One-third of sites had zero seedlings and saplings, while a quarter of sites had densities above 2000 juvenile trees ha−1, in part due to high densities of lodgepole pine saplings. We assessed stocking adequacy by comparing observed juvenile conifer densities to local recommendations for specific plant associations, and found densities did not meet minimum stocking levels in approximately 35% of sites. The most important variables explaining juvenile conifer presence were topographic heat load and distance to live seed source, with the probability of juvenile conifer presence declining below 50% at approximately 100 m from a live seed source. Douglas-fir seedlings were less likely to be found on sites with high heat load than ponderosa pine, and drought conditions in the first three years post-fire reduced Douglas-fir regeneration. Post-fire drought also reduced the probability of achieving minimum stocking levels. Our findings indicate that juvenile conifer densities on warmer slopes within large, high-severity burn areas may be insufficient to meet local silvicultural guidelines without supplementary replanting, especially when moisture availability in the first few years post-fire is low. Some of these marginal sites may transition to shrub or grassland for the foreseeable future, though further research is needed to confirm regional post-fire successional trajectories. The findings from this study can inform post-fire and climate-adapted forest management in the inland Northwest.

Aggregation behavior of juvenile Neptunea cumingii and effects on seed production

Neptunea cumingii is an important nutrition-rich economic species in China. Juveniles of N. cumingii suffer from high mortality at low temperatures, which has proved a limiting factor in raising seedlings in artificial habitats. Previous research has shown that N. cumingii displays aggregation behavior in response to adverse environmental changes. Therefore, we determined the effects of temperature, food, size of juvenile snails, substratum type, and density of juvenile snails on the aggregation behavior of N. cumingii. Results show that, at a low (4°C) or a high (22°C) temperature, juvenile snails adjusted to the inhospitable environment by exhibiting increased aggregation behavior. However, their aggregation behaviors differed at these two temperatures. There was no significant difference in the aggregation rate, but the typical aggregation size was larger at 4°C than at 22°C. At 10°C or 16°C, aggregation behavior of juvenile snails reduced. Aggregation increased in the satiation treatment at 10°C and 16°C. Small-sized juveniles tended to have higher aggregation rates (92.22%) and a larger typical aggregation size. More juveniles were distributed in the bottom of shaded substrata. A larger typical aggregation size or higher density significantly reduced the mortality of juvenile snails at a low temperature (4°C). These results broaden our understanding of gastropod aggregation behavior and can be used to develop and improve commercial breeding strategies and resource recovery for N. cumingii.

Reef benthic composition and coral communities at the Wuzhizhou Island in the south China sea: The impacts of anthropogenic disturbance

The responses of reef benthic substrata and coral communities to anthropogenic disturbances at the Wuzhizhou Island (WZZ, off the southeast coast of the Hainan Island in the South China Sea) were examined in 2007–2017. A total of 90 scleractinia coral species were recorded at WZZ in 2017. Cluster analysis and ANOSIM analysis of reef benthic composition suggested that WZZ can be divided into the north and south zones with significantly different characteristics. Indeed, anthropogenic disturbance (i.e., tourism activity and land use) has been intense in the north zone, whereas the south zone has not been as much disturbed. Coral reefs in the north zone suffered from stronger turbidity and nutrient enrichment. Compared with the south zone, the north zone had significantly lower coverage of stony coral (e.g. Acropora, Montipora and Pocillopora) and soft coral, juvenile coral density but significantly higher coverage of rock/rubble, sand, hydrocoral and sponge. Redundancy analysis demonstrated that turbidity and dissolved nutrients (dissolved inorganic nitrogen or NH4+) were the significant factors in explaining the spatial distribution of reef benthic substrata and coral communities in 2017. The remarked decline of live coral cover in the north zone of WZZ during 2007–2016 can be associated with intensive construction, land use change, and tourism development. These results suggested that anthropogenic disturbances may have degenerated environmental conditions and affected the coral reefs at WZZ.

Polyculture potentials of Galda (Macrobrachium rosenbergii) with Heteropneustes fossilis and Clarias batrachus in South-western coastal ghers of Bangladesh

Prawn (Macrobrachium rosenbergii) culture is socially more acceptable, technically and economically viable and sustainable. The freshwater catfishes Heteropneustes fossilis (shing) and Clarias batrachus (magur) adapt well to hypoxic water bodies and high stocking densities as well. So, shing and magur may be a good candidate to culture with prawn in ponds/ghers to save the farmers from losing their investment in case of shrimp mortality and getting additional income from fish. With this view, this study was conducted to evaluate the feasibility of polyculture with three treatments each with three replications. Stocking density of shing was variable i.e., 200nos/decimal in T1, 300nos/decimal in T2 and 400 nos/decimal in T3. On the other hand, stocking density of magur and prawn juveniles was 50 and 30 nos/decimal respectably for all treatments. The experimental ghers were treated with salt (NaCl) (150g/decimal), potasium permanganate (5g/decimal) along with lime (125 kg/ha). After stocking fish were fed using floating nursery feed containing 32%, protein and 7% lipid at the rate of 10-2% for shing and magur nursing, floating oil coated grower feed (27% protein and 6% lipid) at the rate of 6-2% for shing and magur grow out and prawn grower (30% protein and 7% lipid) at the rate of 6-2.5% of estimated fish and prawn biomass. At least 10% of stocked catfish and galda were sampled fortnightly using cast net. Physico-chemical parameters of the experimental ghers water were monitored at weekly. After six months of culture the highest growth performance (47.0 g) and survival (19.94%) for shing obtained from T3. Whereas the average growth of shing was recorded 37.02 and 41.14g; growth of magur 99.21g and 99.51g and growth of galda 69.74 and 70.19 for Treatment T1 and T2 respectively. Except ammonia and iron content the other observed parameters of ghers water found congenial for fish health. The value of Benefit-Cost Ratio (BCR) was 1.4 that seems to be profitable and feasible of this polyculture practice.

Sea urchins (diadematids) promote coral recovery via recruitment on Taiwanese reefs

Coral reefs are of global concern in the face of increasing anthropogenic disturbance. Much research has focused on the negative factors associated with coral reef decline, but few have documented the positive factors in relation to recovering coral reefs. Here, we report a positive quantitative association between sea urchins (diadematids), coral recruitment and coral recovery, recorded along Taiwanese coral reefs. We monitored coral cover change, juvenile coral density, herbivore density (fishes, sea urchins, gastropods) and macroalgal cover, along three reefs between 2012 and 2015. Multivariable regression analyses revealed that sea urchin (diadematids) density was the primary (positive) driver, explaining 74% of variation in coral cover change and 89% in coral juvenile density among sites and years. The relationship between sea urchin density and coral juvenile density was especially evident for four common coral genera: Acropora, Dipsastraea, Pocillopora and Porites. These results suggest that diadematid urchins enhance coral recovery on these reefs by promoting the recruitment of corals. The density of juvenile corals was also found to explain 67% of variation in coral cover change, highlighting the potential use of coral juvenile density as a proxy for coral recovery potential in coral resilience studies.

Early recovery dynamics of turbid coral reefs after recurring bleaching events

The worlds’ coral reefs are declining due to the combined effects of natural disturbances and anthropogenic pressures including thermal coral bleaching associated with global climate change. Nearshore corals are receiving increased anthropogenic stress from coastal development and nutrient run-off. Considering forecast increases in global temperatures, greater understanding of drivers of recovery on nearshore coral reefs following widespread bleaching events is required to inform management of local stressors. The west Pilbara coral reefs, with cross-shelf turbidity gradients coupled with a large nearby dredging program and recent history of repeated coral bleaching due to heat stress, represent an opportune location to study recovery from multiple disturbances. Mean coral cover at west Pilbara reefs was monitored from 2009 to 2018 and declined from 45% in 2009 to 5% in 2014 following three heat waves. Recruitment and juvenile abundance of corals were monitored from 2014 to 2018 and were combined with biological and physical data to identify which variables enhanced or hindered early-stage coral recovery of all hard corals and separately for the acroporids, the genera principally responsible for recovery in the short-term (<7 years). From 2014 to 2018, coral cover increased from 5 to 10% but recovery varied widely among sites (0–13%). Hard coral cover typically recovered most at shallower sites that had higher abundance of herbivorous fish, less macroalgae, and lower turbidity. Similarly, acroporid corals recovered most at sites with lower turbidity and macroalgal cover. Juvenile acroporid densities were a good indicator of recovery at least two years after they were recorded. However, recruitment to settlement tiles was not a good predictor of total coral or acroporid recovery. This study shows that coral recovery can be slower in areas of high turbidity and the rate may be reduced by local pressures, such as dredging. Management should focus on improving or maintaining local water quality to increase the likelihood of coral recovery under climate stress. Further, in turbid environments, juvenile coral density predicts early coral recovery better than recruits on tiles and may be a more cost-effective technique for monitoring recovery potential.

MON-387 Association Between Vitamin D Level and Bone Mineral Density in Korean Adolescents

IntroductionFractures are common in pediatric population, and lower bone density increases the risk of fracture. Most bone acquisition happens during youth, so juvenile bone mineral density (BMD) assessment is important. There are many factors associated with low BMD, including vitamin D status, calcium intake, low body weight, and physical activity. Among these, our investigation focused on the association of BMD with vitamin D in adolescents.MethodsThis study investigated data of 1,063 adolescents aged 12-18 years from the fifth and sixth Korea National Health and Nutritional Examination Survey (2009-2011). The association of various factors (vitamin D level, calcium intake, body mass index (BMI), lean mass, fat mass, and physical activity) with BMD Z-scores in whole body, lumbar spine, total femur, and femur neck were analyzed. We defined vitamin D deficiency (≤ 12 ng/mL), vitamin D insufficiency (12-20 ng/mL), and sufficiency (> 20ng/mL) according to the 25-hydroxyvitamin D (25-OHD) level. We analyzed association between BMD and vitamin D levels after adjusting for other factors.ResultsThe mean 25-OHD level of subjects was low (16.28 ng/ml). Of all subjects, 21.9% were vitamin D deficient, and 58.5% were vitamin D insufficient. Among the vitamin D groups, the vitamin D sufficient group had significantly higher BMD Z-scores than the vitamin D deficient group in whole body, lumbar spine, and femur neck. The sufficient vitamin D group had higher BMD Z-score than the vitamin D insufficient group in femur neck, and the vitamin D insufficient group had higher BMD Z-score than the vitamin D deficient group in whole body. Among various factors, vitamin D status, calcium intake, BMI, lean mass, fat mass, and physical activity were positively associated with BMD Z-scores. In particular, lean mass was the strongest independent factor. Vitamin D levels were positively associated with the BMD Z-scores even after adjusting for other factors.ConclusionsVitamin D deficiency and insufficiency were common among adolescents. This study suggested that vitamin D level was positively associated with BMD, and that sufficient vitamin D level was needed to prevent low BMD. Vitamin D status is an important factor of BMD in adolescents.

Early predictors of female lifetime reproductive success in a solitary hibernator: evidence for "silver spoon" effect.

Fitness consequences of early-life conditions remain unclear and poorly studied in mammals. Based on long-term observations of yellow ground squirrels (Spermophilus fulvus), we identified early determinants of female fitness by analyzing the effects of early-life individual and environmental characteristics (weaning weight, weight gain rate, date of natal emergence, natal litter size, location of the natal burrow, local density of juveniles, population density and precipitation in the post-weaning period) on lifetime reproductive success (LRS). We found high variation and right-skewed distribution in all five LRS components (survival to adulthood, adult lifespan, and lifetime numbers of weaned litters, weanlings, and yearling offspring). Numbers of litters, weanlings, and adult offspring were correlated with each other and increased with lifespan, confirming that longevity is a better predictor of LRS than fecundity. Survival to adulthood was the most sensitive fitness component to early conditions and was higher in females (a) with greater weaning weight, (b) born further from human settlement and (c) born at lower population density. Population density at birth was the best early predictor of all LRS components and negatively influenced adult lifespan and numbers of weanlings and yearling offspring. Early growth rate positively affected the probability of reproducing after the first hibernation and the number of offspring weaned. Such syndrome of high-quality (heavy and fast-growing) young born in a favourable environment ("a silver spoon effect") with downstream damping fitness consequences has been observed so far in only a few mammalian species.

Quantifying fisheries enhancement from coastal vegetated ecosystems

Coastal ecosystems are estimated to support 95% of the world’s commercially-important fish, owing largely to their provision of nursery habitat for juveniles; however, systematic databases with such data are scarce. By systematically reviewing the literature across Australia, we quantified fisheries enhancement from three key coastal vegetated habitats: seagrass meadows, mangrove forests, and tidal marshes. From juvenile densities, we modelled adult fish biomass enhancement resulting from these structured habitats and linked fish of economic importance with market values. We found that seagrass displayed higher per hectare abundance, biomass and economic enhancement compared to mangroves and tidal marshes. On average, one hectare of seagrass supported 55,000 more fish annually compared to unvegetated seabed, resulting in an additional biomass of 4000 kg and a value increase of AUD 21,200 annually. Mangroves supported 19,000 more fish, equivalent to 265 kg−1 ha−1 y−1, and tidal marshes provided a modest 1700 more fish, equivalent to 64 kg−1 ha−1 y−1. The most abundant fish across all ecosystems were small, non-commercial species (e.g. gobies and glassfish), but the highest biomass and economic value originated from larger, longer-lived fish that are regularly targeted by fisheries (e.g. breams and mullets). By quantifying enhancement value across Australia, our findings provide further evidence for, the benefit these critical habitats provide in supporting coastal fisheries and human well-being.