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 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.

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 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.

Effects of temperature and salinity on immature and juvenile Neomysis americana (Smith) (Crustacea; Mysidacea)

1982 ◽  
Vol 60 (11) ◽  
pp. 2725-2728 ◽  
Author(s):  
D. S. Pezzack ◽  
S. Corey
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Salinity Tolerance ◽  
Environmental Conditions ◽  
Tolerance Range ◽  
Effects Of Temperature

The temperature and salinity tolerance of newly released young Neomysis americana was measured for two acclimation temperatures and salinities. The newly released young possess a wide tolerance range to changes in temperature and salinity. Salinities as low as 4‰ had no effect on the molt or growth rate. The effect of environmental conditions on the distribution and life history are discussed.

Reproductive value and analyses of population dynamics of age-structured populations

2021 ◽  
pp. 285-298
Author(s):  
Bernt-Erik Sæther ◽  
Steinar Engen
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Age Structure ◽  
Good Description ◽  
Age Distribution ◽  
Reproductive Rate ◽  
Environmental Stochasticity ◽  
Reproductive Value ◽  
Long Run ◽  
Age Structured

Many populations of especially long-lived species show large temporal variation in age structure, which can complicate estimating of important population parameters. This occurs because it can be difficult to disentangle whether variation in numbers is due to fluctuations in the environment or caused by changes in the age distribution. This chapter shows that fluctuations in the total reproductive value of the population, that is, the sum of all individual reproductive values, often provide a good description of the population dynamics but still is not confounded by fluctuations in age structure. Because the change in the total reproductive rate is exactly equal to the growth rate of the population, this quantity enables decomposition of the long-run growth rate into stochastic components caused by age-specific variation in demographic and environmental stochasticity. The chapter illustrates the practical application of this approach in stochastic demography by analyses of the dynamics of several populations of birds and mammals. It puts a strong focus on these methods being particularly useful in viability analyses of small populations of vulnerable or endangered species.

A skeletochronological study of age, growth and longevity of Rana macrocnemis populations from four locations at different altitudes in Turkey

2011 ◽  
Vol 32 (1) ◽  
pp. 113-118 ◽  
Author(s):  
Emel Çakır ◽  
Ufuk Bülbül ◽  
Nurhayat Özdemir ◽  
Bilal Kutrup
Keyword(s):  
Life History ◽  
Age Structure ◽  
Sexual Maturity ◽  
Life History Traits ◽  
Maximum Lifespan ◽  
Population Age Structure ◽  
Positive Correlation ◽  
Males And Females ◽  
Different Altitudes ◽  
Rana Macrocnemis

AbstractWe examined life-history traits such as population age structure, growth and longevity of Iranian Long-Legged frogs (Rana macrocnemis) from 4 different locations at different altitudes in Turkey by skeletochronology performed on the phalanges. The maximum lifespan was 5 years in Maçka (350 m a.s.l.), 6 years in Hıdırnebi (1430 m a.s.l.), 8 years in Sarıkamış (2276 m a.s.l.) and 10 years in Ovit (2850 m a.s.l.). Age at sexual maturity of both males and females was 2-3 years in the Maçka, Hıdırnebi and Sarıkamış populations, while 3-4 years for males and 3-5 years for females in the Ovit population. In all populations, males and females did not exhibit any differences in terms of mean age and SVL except for Sarıkamı¸s where the males were significantly larger than the females. A positive correlation was observed between age and SVL for both sexes in all populations except for the males of the Maçka population.

scholarly journals Life history variation across four decades in a diverse population complex of Atlantic salmon in a large subarctic river

2019 ◽  
Vol 76 (1) ◽  
pp. 42-55 ◽  
Author(s):  
Jaakko Erkinaro ◽  
Yann Czorlich ◽  
Panu Orell ◽  
Jorma Kuusela ◽  
Morten Falkegård ◽  
...  
Keyword(s):  
Life History ◽  
Fresh Water ◽  
Life Histories ◽  
Age Distribution ◽  
Large River ◽  
Life History Strategies ◽  
Sampling Effort ◽  
Life History Variation ◽  
Water Age ◽  
Long Term Trends

We used over 154 000 scale samples collected from salmon fisheries in the large River Teno system over a 40-year period to quantify life history diversity and long-term trends. We identified 120 different life history strategies, including combinations of smolt (2–8) and sea ages (1–5) and previous spawning events. Most strategies were rare; 60% of individuals matured after 1 year at sea following 3–5 years in fresh water. Age at maturity changed with an increase in two-sea-winter salmon and previous spawners and a decline in three-sea-winter fish. Smolt age distribution showed a decreasing proportion of age-3 smolts, while that of age-5 smolts increased. Fishing gear and fishing season times selected for fish differing in life history strategies. Temporal variation in life histories reflected changes in both fisheries and the changing environment. There was an inverse relationship between years spent in fresh water and sea age. Biocomplexity was manifested by the multiple year classes (6–11) present in annual runs, which increased with years, reflecting an increase both in previous spawners and sampling effort. The high number of cohorts spawning simultaneously each year indicates strong generational overlap, which has been suggested to maintain genetic diversity and thereby resilience via the portfolio effect.

scholarly journals Flood pulse effects on multispecies fishery yields in the Lower Amazon

2015 ◽  
Vol 2 (11) ◽  
pp. 150299 ◽  
Author(s):  
Leandro Castello ◽  
Victoria J. Isaac ◽  
Ram Thapa
Keyword(s):  
Interannual Variability ◽  
Complex Dynamics ◽  
Flood Pulse ◽  
Large River ◽  
Fishing Effort ◽  
Water Levels ◽  
Fish Biomass ◽  
River Floodplain ◽  
River Floodplains ◽  
Flood Pulses

Seasonally fluctuating water levels, known as ‘flood pulses’, control the productivity of large river fisheries, but the extent and mechanisms through which flood pulses affect fishery yields are poorly understood. To quantify and better understand flood pulse effects on fishery yields, this study applied regression techniques to a hydrological and fishery record (years 1993–2004) for 42 species of the Amazon River floodplains. Models based on indices of fishing effort, high waters and low waters explained most of the interannual variability in yields ( R 2 =0.8). The results indicated that high and low waters in any given year affected fishery yields two and three years later through changes in fish biomass available for harvesting, contributing 18% of the explained variability in yields. Fishing effort appeared to amplify high and low water effects by changing in direct proportion to changes in fish biomass available for harvesting, contributing 62% of the explained variability in yields. Although high waters are generally expected to have greater relative influence on fishery yields than low waters, high and low waters exerted equal forcing on these Amazonian river-floodplain fishery yields. These findings highlight the complex dynamics of river-floodplain fisheries in relation to interannual variability in flood pulses.

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

To 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.

scholarly journals Influence of trematode infections on in situ growth rates of Littorina littorea

1999 ◽  
Vol 79 (3) ◽  
pp. 425-430 ◽  
Author(s):  
Kim N. Mouritsen ◽  
A. Gorbushin ◽  
K. Thomas Jensen
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Differential Effect ◽  
Littorina Littorea ◽  
In Situ Growth ◽  
Trematode Infections ◽  
Effect On Growth

The influence of various species of digenean trematodes on the in situ growth rate of Littorina littorea (Gastropoda: Prosobranchia) from different habitats was investigated. The main results showed: (1) that infections either reduced or had no significant effect on growth in comparison with uninfected snails; (2) that the same type of infection could have a differential effect on growth depending on the habitat/population from which the snails originated. These findings are consistent with the life history hypothesis expecting no or a stunting effect of trematode infections on the growth of longer-lived snails, but do also emphasize that growth rates following trematode invasion can be significantly modified by environmental conditions, such as, food availability.

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