scholarly journals Climate causes shifts in grey seal phenology by modifying age structure

2021 ◽  
Vol 288 (1964) ◽  
Author(s):  
James C. Bull ◽  
Owen R. Jones ◽  
Luca Börger ◽  
Novella Franconi ◽  
Roma Banga ◽  
...  
Keyword(s):  
Climate Change ◽  
Age Structure ◽  
Census Data ◽  
Age Distribution ◽  
Population Level ◽  
Ecosystem Change ◽  
Population Census ◽  
Sea Temperature ◽  
Population Age Structure ◽  
Phenological Shifts

There are numerous examples of phenological shifts that are recognized both as indicators of climate change and drivers of ecosystem change. A pressing challenge is to understand the causal mechanisms by which climate affects phenology. We combined annual population census data and individual longitudinal data (1992–2018) on grey seals, Halicheorus grypus , to quantify the relationship between pupping season phenology and sea surface temperature. A temperature increase of 2°C was associated with a pupping season advance of approximately seven days at the population level. However, we found that maternal age, rather than sea temperature, accounted for changes in pupping date by individuals. Warmer years were associated with an older average age of mothers, allowing us to explain phenological observations in terms of a changing population age structure. Finally, we developed a matrix population model to test whether our observations were consistent with changes to the stable age distribution. This could not fully account for observed phenological shift, strongly suggesting transient modification of population age structure, for example owing to immigration. We demonstrate a novel mechanism for phenological shifts under climate change in long-lived, age- or stage-structured species with broad implications for dynamics and resilience, as well as population management.

scholarly journals Population Age Structure, Complex Socio-Demographic Systems and Resilience Potential: A Spatio-Temporal, Evenness-Based Approach

2019 ◽  
Vol 11 (7) ◽  
pp. 2050 ◽  
Author(s):  
Massimo Cecchini ◽  
Sirio Cividino ◽  
Rosario Turco ◽  
Luca Salvati
Keyword(s):  
Population Structure ◽  
Age Structure ◽  
Census Data ◽  
Principal Component ◽  
System Thinking ◽  
Italian Population ◽  
Comprehensive Overview ◽  
Population Age Structure ◽  
Evenness Index ◽  
Over Time

The present study illustrates an original approach grounded on entropy theory and complex system thinking with the aim to investigate changes over time and space in population structure by age in Italy, in light of socioeconomic resilience and post-crisis recovery potential. Assuming that population structure may reflect different levels of resilience to exogenous shocks, a Pielou J evenness index was calculated on census data made available every 10 years (1861–2011) with the aim to identify compositional homogeneity (or heterogeneity) in the age structure of the Italian population. Trends over time in the Pielou J evenness index were identified using descriptive statistics, comparison with ancillary demographic indicators and multivariate exploratory techniques including principal component analysis. The empirical results allowed the identification of multiple dimensions of demographic transition in Italy, distinguishing two phases, the former encompassing a relatively long time period between 1861 and 1936, and the latter covering a shorter period between 1936 and 2011. A spatially-explicit analysis of Pielou J evenness indices applied to the population age structure of each Italian municipality at the latest survey (2017) finally provided a comprehensive overview of the demographic characteristics likely influencing the resilience potential of local districts. The empirical evidence outlined the consolidation of a coastal–inland divide as a result of the complex linkage between demographic dynamics and local background contexts.

scholarly journals Age Distribution Model For GCC Countries

2011 ◽  
Vol 8 (11) ◽  
Author(s):  
Shafiqur Rahman
Keyword(s):  
Goodness Of Fit ◽  
Census Data ◽  
Age Distribution ◽  
Developed Countries ◽  
Distribution Model ◽  
School Age Children ◽  
Population Census ◽  
Goodness Of Fit Test ◽  
Chi Square ◽  
Gcc Countries

Efficient and reliable estimates of the proportions of population at different age levels are essential for making quality budget of any developing or developed nation. These estimates are obtained from the best-fitted age distribution model and can be used to find the number of school age children, number of pensioners etc. Past population census data of GCC countries are analyzed to find the best-fitted age distribution model applying chi-square goodness of fit test and model selection criteria and observed that the age distribution of most of the GCC countries is exponential. A comparative study of the age distributions of six GCC countries with some developed countries is also provided.

scholarly journals Population age structure only partially explains the large number of COVID-19 deaths at the oldest ages

2020 ◽  
Author(s):  
Anthony Medford ◽  
Sergi Trias-Llimós
Keyword(s):  
Old Age ◽  
Age Structure ◽  
Age Distribution ◽  
Case Fatality ◽  
European Countries ◽  
Population Age Structure ◽  
Country Comparison ◽  
Cross Country ◽  
Age Structures

AbstractTo date any attention paid to the age shape of COVID-19 deaths has been mostly in relation to attempts to understand the differences in case fatality rates between countries. The aim of this paper is to explore differences in age distribution of deaths from COVID-19 among European countries which have old age structures. We do this by way of a cross-country comparison and put forward some reasons for potential differences.

Population age structure and growth in four syntopic amphibian species inhabiting a large river floodplain

2003 ◽  
Vol 81 (6) ◽  
pp. 1096-1106 ◽  
Author(s):  
Dan Cogalniceanu ◽  
Claude Miaud
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Age Structure ◽  
Environmental Conditions ◽  
Age Distribution ◽  
Large River ◽  
Danube River ◽  
Population Age Structure ◽  
River Floodplain ◽  
River Floodplains

River floodplains are disturbance-dominated landscapes where floods are major regulators of both aquatic and nearby terrestrial communities. Amphibians are common inhabitants of floodplains and their life cycle depends on both aquatic and terrestrial habitats. We focused on how different syntopic species of amphibians reacted to the environmental conditions of a large river floodplain. We examined life-history traits such as population age structure and growth in small- and large-bodied species of anurans and urodeles in the lower Danube River floodplain in Romania. Two newt species, Triturus vulgaris (small-bodied) and Triturus dobrogicus (large-bodied), and two anuran taxa, Bombina bombina (small-bodied) and the Rana esculenta complex (large-bodied), were included in the study. The ages of individuals estimated by skeletochronology varied from 3 to 5–6 years for T. vulgaris and from 2–3 to 4–5 years for T. dobrogicus. In the anurans, ages varied from 2 to 5 years in B. bombina and from 4 to 10 years in the R. esculenta complex. The numbers of breeding opportunities (i.e., the number of years the adults reproduce) are similar in both newt species (3), while growth rates and age at maturity differ between the large- and small-bodied species. In anurans, the number of breeding opportunities for the smallest species, B. bombina (4), is associated with a high growth rate and earlier maturation. In the larger R. esculenta complex, the higher number of breeding opportunities (7) is associated with a low growth rate and delayed maturation. The study of age distribution and associated parameters provides useful information on population life history. We discuss how age structure and growth of amphibian populations in large river floodplains can be used as indicators of environmental conditions.

scholarly journals Covid-19 and Population Age Structure

2020 ◽  
Author(s):  
Ajit Haridas ◽  
Gangan Prathap
Keyword(s):  
Empirical Evidence ◽  
Age Structure ◽  
Age Distribution ◽  
Case Fatality ◽  
Mortality Rates ◽  
Epidemiological Studies ◽  
Cross Protection ◽  
Large Cohort ◽  
Population Age Structure

AbstractEpidemiological studies suggest that age distribution of a population has a non-trivial effect on how morbidity rates, mortality rates and case fatality rates (CFR) vary when there is an epidemic or pandemic. We look at the empirical evidence from a large cohort of countries to see the sensitivity of Covid-19 data to their respective median ages. The insights that emerge could be used to control for age structure effects while investigating other factors like cross-protection, comorbidities, etc.

scholarly journals Trends in Age Structure and Ageing Population in Nepal

2020 ◽  
Vol 1 (1) ◽  
pp. 103-114
Author(s):  
Kamala Bhandari
Keyword(s):  
Urban Area ◽  
Age Structure ◽  
Census Data ◽  
Population Census ◽  
Ageing Population ◽  
Hill Region ◽  
Rural And Urban ◽  
Working Age ◽  
Structure Of Population ◽  
Rural And Urban Area

The study attempts to examine the trend in the age structure of population and elderly population and its geographic and demographic variation in respect to the fedral structured country based on the census data. The study found noticeable changes in the age structure of the population in the country. The share of children is shrinking with growing proportions of older population aged 60 and above throughout the Nation. More than half of population falls in the 15-59 years category that conforms Nepal population is primarily young, which is also known as the 'youth bulge' or 'demographic dividends' and will shift into the category of 60 and above in a few decades. Hence the Nepal's population is gradually ageing over the years. The proportion of children and old aged population was observed higher in Mountain (38% and 8.8%)), rural area (38% and 8.8%) and working age population was in hill region (58%) and in urban area (59%) along with province 3. According to the 2011 population census, the proportion of population aged 60 and above is 8.1 percent, majority of them are in their sixties (69%) and observed same in all regions of the country. As measured by sex ratio in both rural and urban area female outnumber male and also reported the expectation of life is higher for female then male in this age group of the country. Among the 77 districts Gorkha (12.75%) reported the highest, and Jajarkot (5.12%), reported the lowest proportion of their population being old.

scholarly journals Cold comfort: Arctic seabirds find refugia from climate change and potential competition in marginal ice zones and fjords

AMBIO ◽  
2021 ◽  
Author(s):  
Anne-Sophie Bonnet-Lebrun ◽  
Thomas Larsen ◽  
Thorkell Lindberg Thórarinsson ◽  
Yann Kolbeinsson ◽  
Morten Frederiksen ◽  
...  
Keyword(s):  
Climate Change ◽  
Census Data ◽  
Foraging Ecology ◽  
Cold Water ◽  
Conservation Status ◽  
Population Decline ◽  
Sea Temperature ◽  
Species Dominance ◽  
Arctic Seabirds ◽  
Brunnich’S Guillemot

AbstractClimate change alters species distributions by shifting their fundamental niche in space through time. Such effects may be exacerbated by increased inter-specific competition if climate alters species dominance where competitor ranges overlap. This study used census data, telemetry and stable isotopes to examine the population and foraging ecology of a pair of Arctic and temperate congeners across an extensive zone of sympatry in Iceland, where sea temperatures varied substantially. The abundance of Arctic Brünnich’s guillemot Uria lomvia declined with sea temperature. Accessibility of refugia in cold water currents or fjords helped support higher numbers and reduce rates of population decline. Competition with temperate Common guillemots Uria aalge did not affect abundance, but similarities in foraging ecology were sufficient to cause competition when resources are limiting. Continued warming is likely to lead to further declines of Brünnich’s guillemot, with implications for conservation status and ecosystem services.

ENVIRONMENTAL IMPACTS OF THE 1985 ARCO ANCHORAGE OIL SPILL: 1988 CONCLUSIONS1

1989 ◽  
Vol 1989 (1) ◽  
pp. 459-462
Author(s):  
Eugene R. Mancini ◽  
June Lindstedt-Siva ◽  
Dilworth W. Chamberlain
Keyword(s):  
Crude Oil ◽  
Census Data ◽  
Monitoring Program ◽  
Population Level ◽  
Taxonomic Diversity ◽  
Benthic Invertebrate ◽  
Sediment Chemistry ◽  
Population Census ◽  
Beach Sediments ◽  
Invertebrate Population

ABSTRACT The beach of Ediz Hook, Port Angeles, Washington, was heavily oiled by Alaska North Slope (ANS) crude oil spilled subsequent to the grounding of the Arco Anchorage on December 21, 1985. Intertidal crude oil concentrations measured in beach sediments ranged from less than 50 to 20,000 ppm, with an average of 2,240 ppm. Beach reclamation efforts, concluded in April 1986, reduced average crude oil concentrations to 670 ppm. An intertidal and subtidal sediment chemistry and benthic invertebrate monitoring program was initiated at Ediz Hook in 1986 and was concluded in early 1988. Sediment chemistry data indicated a decline in mean intertidal concentrations from 670 to 110 ppm between April 1986 and July 1987. Shallow subtidal concentrations decreased from a mean of 460 to 110 ppm in the same time period. Benthic invertebrate population indices, developed with core and box sampler data, generally demonstrated a negative correlation with sediment crude oil concentrations. Organism density, taxonomic diversity and biomass increased significantly at numerous stations during the course of the monitoring studies. Successful bivalve population recruitment and growth were evident for several hardshell clam species by the fall of 1987. There was no evidence of petroleum-derived hydrocarbons in the edible tissues of salmonids (rainbow trout and Atlantic salmon) which were gathered for several months after the spill from a net-pen culturing facility in Port Angeles. Despite vigorous bird rehabilitation efforts, approximately 80 percent of the 1,917 oiled birds perished. Pre- and post-spill population census data indicate, however, that population level impacts did not occur. Various reconnaissance, monitoring and damage assessment investigations conducted during and after the spill have documented the environmental value of a rapid and effective spill response and cleanup effort. Significant impacts associated with the spill were short-term in nature and generally limited to the immediate spill area.

scholarly journals Population Distribution Model For Oman

2011 ◽  
Vol 10 (1) ◽  
Author(s):  
Shafiqur Rahman
Keyword(s):  
Goodness Of Fit ◽  
Census Data ◽  
Population Distribution ◽  
Age Distribution ◽  
Developed Countries ◽  
Distribution Model ◽  
Population Census ◽  
Goodness Of Fit Test ◽  
Gulf Countries ◽  
Developed Nations

Past population census data of Sultanate of Oman are analyzed to find the best-fitted age distribution model applying chi-square goodness of fit test and model selection criteria. It is observed that the age distribution of the Omani population is exponential. The population figures for different age groups of Oman are estimated using exponential distribution. Age distribution of Omani population is compared with that of other Gulf countries and also with some developed nations. It is observed that, unlike other developed countries of the world, the age distribution of Omani population does not change significantly over the last two decades. It is also observed that the median age of the Omani population is about half of that of other developed nations. Ageing is not a problem for Oman or Gulf countries, but it is a big issue for most developed countries. Young populations in Oman are significantly higher than that of developed countries.

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