Production and Population Dynamics of the Crayfish Orconectes virilis in Three Michigan Lakes

1977 ◽  
Vol 34 (11) ◽  
pp. 2030-2040 ◽  
Author(s):  
Walter T. Momot ◽  
Howard Gowing
Keyword(s):  
Population Dynamics ◽  
Growth Rates ◽  
Age Groups ◽  
Mortality Rates ◽  
Reproductive Age ◽  
Annual Production ◽  
Effective Density ◽  
Orconectes Virilis ◽  
Brood Stock ◽  
Density Dependent

Fluctuations in mortality rather than in growth rates produced most of the year-to-year differences in biomass accumulation of three different populations of the crayfish Orconectes virilis. Yearly biomass changes resulted from density-dependent control of mortality and fecundity during certain portions of the life cycle. Density-dependent changes in mortality rates controlled population size for adults in all lakes and for young-of-the-year in two of the three study lakes. Growth rates were much less responsive to fluctuating densities. Disparity between the number of ovarian and attached eggs increased as density of age I+ crayfish increased. This provided a strong density regulator on fecundity. Differences occurred in the number of recruits produced by a brood stock that survive to the end of the first growing season in the various lakes. Yet the number of females surviving to reproductive age 2 yr later was strongly regulated. Strong population regulation produced two female recruits of breeding age for every two–six parental breeding females. The high biomass and production levels of crayfish discovered in West Lost Lake in 1962–63 also occurred in the other area lakes. Higher but variable levels of recruitment resulted in larger standing crops and production in West Lost lake. This resulted from less effective density controls on the mortality rates of younger age-groups in that lake. Despite great variation in biomass of from 46 to 213 kg/ha and annual production from 60 to 142 kg/ha, the annual turnover ratio of the biomass was found to vary only between 0.94 and 1.53. Key words: crayfish, Orconectes virilis, population dynamics, annual production, Michigan lakes

Cycle de développement, croissance et production de Pisidium amnicum (Mollusca: Bivalvia) dans le Saint-Laurent (Québec)

1981 ◽  
Vol 59 (12) ◽  
pp. 2350-2359 ◽  
Author(s):  
B. Vincent ◽  
G. Vaillancourt ◽  
N. Lafontaine
Keyword(s):  
Population Dynamics ◽  
Sexual Maturity ◽  
Dry Weight ◽  
Mortality Rates ◽  
The Other ◽  
Annual Production ◽  
Bithynia Tentaculata ◽  
The Mean ◽  
Total Dry Weight ◽  
St Lawrence River

The population dynamics of Pisidium amnicum have been studied in one population of the St. Lawrence River over a 2-year period during which 19 samples were taken. The species can live up to 3 years and it is iteroparous; individuals generally attain sexual maturity after 1 year and they reproduce twice, once at 2 and once at 3 years of age. In adults, mortality is lower in winter than during the rest of the year and mortality rates are twice as high during the 1st year than during the 2nd year. Total dry weight (PT, in milligrams) is related to maximum length (L, in millimetres) according to the equation PT = 0.0283∙L3,80 and flesh dry weight (PC, in milligrams) is related to length as follows: PC = 0.007∙L3,18. The annual production to mean biomass (P/B) ratio is 1.4, the mean annual production being 1.298 mg/m2 of total dry weight and 107 mg/m2 of flesh weight. Comparing these results with those obtained for the gastropod Bithynia tentaculata in the same environment and at the same period of the year has shown that the growth of Pisidium amnicum is far less influenced by the temperature regime than that of the other species and that its production is at least 10 times lower.

scholarly journals Effects of phenological synchronization on caterpillar early-instar survival under a changing climate

2018 ◽  
Vol 48 (3) ◽  
pp. 247-254 ◽  
Author(s):  
Emma Despland
Keyword(s):  
Population Dynamics ◽  
Host Plants ◽  
Larval Mortality ◽  
Mortality Rates ◽  
Chemical Defenses ◽  
Population Fluctuations ◽  
Density Dependent ◽  
Early Instar ◽  
Species Specific ◽  
Very High

Early-instar caterpillars experience very high and often very variable mortality; if it is density dependent, it can be a key factor in outbreak dynamics. Plant physical and chemical defenses can be extremely effective against young caterpillars, even of specialists. Phenological asynchrony with host plants can lead to dispersal and mortality in the early instars and increased predation or poor nutrition in later instars. Predation on early-instar larvae (including cannibalism) can be extremely high, parasitism appears generally low, and pathogens acquired early in larval development can lead to high mortality in later stadia. Four well-studied species reveal very different roles of early-instar mortality in population dynamics. In spruce budworm and gypsy moth, early-instar mortality rates can be very high; they do not drive outbreak cycles because density dependence is weak, but can modulate cycles and contribute to outbreak size and duration. For the autumnal moth, early-instar survival depends on host plant synchrony, but may or may not be density dependent. For monarch butterflies, the relative importance of larval mortality rates in population dynamics remains unclear. Tritrophic interactions between herbivores, host plants, natural enemies, and microbes play complex and species-specific roles in early-instar ecology, leading to emergent dynamics in population fluctuations. The phenology of these relationships is often poorly understood, making their responses to climate change unpredictable.

Paleodemographic Simulations at Xcambó, Yucatan: Early and Late Classic Population Dynamics in the Northern Maya Territories

2020 ◽  
Vol 31 (4) ◽  
pp. 683-701
Author(s):  
Allan Ortega-Muñoz ◽  
Vera Tiesler ◽  
Thelma Sierra-Sosa ◽  
Andrea Cucina
Keyword(s):  
Population Dynamics ◽  
Growth Rates ◽  
Environmental Changes ◽  
Mortality Rates ◽  
Age At Death ◽  
Late Classic ◽  
Skeletal Collections

Paleodemographic simulations are rare in the Maya region, because generally the skeletal collections do not represent well the ancient living population, are poorly preserved, and lead to flawed age-at-death estimations. The skeletal collection of Xcambó, however, is suitable for paleodemographic analysis and is large enough to enable comparison of paleodemographic trends between the Early (AD 250–550) and Late Classic (AD 550–750) periods. Three demographic simulations were generated; two relied on growth rates calculated from the site's previous archaeodemographic data, and a third simulation was based on a stationary scenario by applying Weiss's (1973) and Séguy and Buchet's (2013) models. All simulations indicate that Xcambó’s Late Classic population was growing faster than its Early Classic peers, with higher rates of survivorship and more severe mortality rates. We argue that the differences are more likely due to shifts in lifestyle and wealth than to environmental changes, as is confirmed by other bioarchaeological and skeletal indicators.

Inequalities and Impact of Socioeconomic-Cultural Factors in Suicide Rates Across Italy

Crisis ◽  
2011 ◽  
Vol 32 (4) ◽  
pp. 178-185 ◽  
Author(s):  
Maurizio Pompili ◽  
Marco Innamorati ◽  
Monica Vichi ◽  
Maria Masocco ◽  
Nicola Vanacore ◽  
...  
Keyword(s):  
Suicide Rate ◽  
Age Groups ◽  
Premature Death ◽  
Mortality Rates ◽  
Mortality Data ◽  
Italian Population ◽  
Comprehensive Overview ◽  
Suicide Rates ◽  
Younger Age ◽  
Age And Sex

Background: Suicide is a major cause of premature death in Italy and occurs at different rates in the various regions. Aims: The aim of the present study was to provide a comprehensive overview of suicide in the Italian population aged 15 years and older for the years 1980–2006. Methods: Mortality data were extracted from the Italian Mortality Database. Results: Mortality rates for suicide in Italy reached a peak in 1985 and declined thereafter. The different patterns observed by age and sex indicated that the decrease in the suicide rate in Italy was initially the result of declining rates in those aged 45+ while, from 1997 on, the decrease was attributable principally to a reduction in suicide rates among the younger age groups. It was found that socioeconomic factors underlined major differences in the suicide rate across regions. Conclusions: The present study confirmed that suicide is a multifaceted phenomenon that may be determined by an array of factors. Suicide prevention should, therefore, be targeted to identifiable high-risk sociocultural groups in each country.

82 The Significant Burden of Burn Injuries in the Middle East: An Epidemiological Study of Nineteen Countries over 27 Years

2021 ◽  
Vol 42 (Supplement_1) ◽  
pp. S56-S57
Author(s):  
Zachary J Collier ◽  
Yasmina Samaha ◽  
Priyanka Naidu ◽  
Katherine J Choi ◽  
Christopher H Pham ◽  
...  
Keyword(s):  
Middle East ◽  
Age Groups ◽  
Mortality Rates ◽  
Burn Injuries ◽  
Burn Care ◽  
Life Years ◽  
Significant Burden ◽  
Mortality Ratio ◽  
Incident Cases ◽  
Age And Sex

Abstract Introduction Despite ongoing improvements in burn care around the world, the burden of burn morbidity and mortality has remined a significant challenge in the Middle East due to ongoing conflicts, economic crises, social disparities, and dangerous living conditions. Here, we examine the epidemiology of burn injuries in the Middle East (ME) relative to socio-demographic index (SDI), age, and sex in order to better define regional hotspots that may benefit most from sustainability and capacity building initiatives. Methods Computational modeling from the 2017 Global Burden of Disease (GBD17) database was used to extrapolate burn data about the nineteen countries that define the ME. Using the GBD17, the yearly incidence, deaths, and Disability-Adjusted Life Years (DALYs) from 1990 to 2017 were defined with respect to age and sex as rates of cases, deaths, and years per 100,000 persons, respectively. Mortality ratio represents the percentage of deaths relative to incident cases. Data from 2017 was spatially mapped using heat-mapping for the region. Results Over 27 years in the ME, an estimated 18,289,496 burns and 308,361 deaths occurred causing 24.5 million DALYs. Burn incidence decreased by 5% globally but only 1% in the ME. Although global incidence continued to decline, most ME countries exhibit steady increases since 2004. Compared to global averages, higher mortality rates (2.8% vs 2.0%) and DALYs (205 vs 152 years) were observed in the Middle East during this time although the respective disparities narrowed by 95% and 42% by 2017. Yemen had the worst death and DALY rates all 27 years with 2 and 2.2 times the ME average, respectively. Sudan had the highest morality ratio (3.7%) for most of the study, twice the ME average (1.8%), followed by Yemen at 3.6%. Sex-specific incidence, deaths, and DALYs in the ME were higher compared to the global cohorts. ME women had the worst rates in all categories. With respect to age, all rates were worse in the ME age groups except in those under 5 years. Conclusions For almost three decades, ME burn incidence, deaths, DALYs, and mortality rates were consistently worse than global average. Despite the already significant differences for burn frequency and severity, especially in women and children, underreporting from countries who lack sufficient registry capabilities likely means that the rates are even worse than predicted.

scholarly journals Mortality Associated with Idiopathic Pulmonary Fibrosis in Northeastern Italy, 2008–2020: A Multiple Cause of Death Analysis

2021 ◽  
Vol 18 (14) ◽  
pp. 7249
Author(s):  
Alessandro Marcon ◽  
Elena Schievano ◽  
Ugo Fedeli
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Cause Of Death ◽  
Age Groups ◽  
Mortality Rates ◽  
Annual Percent Change ◽  
Northeastern Italy ◽  
Mortality Ratio ◽  
The Impact ◽  
Related Mortality

Mortality from idiopathic pulmonary fibrosis (IPF) is increasing in most European countries, but there are no data for Italy. We analysed the registry data from a region in northeastern Italy to assess the trends in IPF-related mortality during 2008–2019, to compare results of underlying vs. multiple cause of death analyses, and to describe the impact of the COVID-19 epidemic in 2020. We identified IPF (ICD-10 code J84.1) among the causes of death registered in 557,932 certificates in the Veneto region. We assessed time trends in annual age-standardized mortality rates by gender and age (40–74, 75–84, and ≥85 years). IPF was the underlying cause of 1310 deaths in the 2251 certificates mentioning IPF. For all age groups combined, the age-standardized mortality rate from IPF identified as the underlying cause of death was close to the European median (males and females: 3.1 and 1.3 per 100,000/year, respectively). During 2008–2019, mortality rates increased in men aged ≥85 years (annual percent change of 6.5%, 95% CI: 2.0, 11.2%), but not among women or for the younger age groups. A 72% excess of IPF-related deaths was registered in March–April 2020 (mortality ratio 1.72, 95% CI: 1.29, 2.24). IPF mortality was increasing among older men in northeastern Italy. The burden of IPF was heavier than assessed by routine statistics, since less than two out of three IPF-related deaths were directly attributed to this condition. COVID-19 was accompanied by a remarkable increase in IPF-related mortality.

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