Increasing impact of COVID-19 on young adults: evidence from hospitalisations in Brazil.

OBJECTIVES: Concerns about the increasing impact of severe COVID-19 in younger individuals in Brazil came after a recent synchronised country-wide wave of cases in Brazil. This communication analyses how hospitalisations due to COVID-19 changed in the age groups 18-49 years and ≥70 years. STUDY DESIGN: Longitudinal study based on secondary data. METHODS: Data from SIVEP-Gripe, a public and open-access database of Severe Acute Respiratory Illness records (including COVID-19 notifications), were used in this study. Statistical control charts examined changes in the magnitude and variation of younger (18-49 years) and older (≥70 years) adults who were hospitalised between 15th March 2020 and 19th June 2021. RESULTS: During the few first weeks of the pandemic in Brazil, the number of COVID-19 hospitalisations increased in older adults but decreased in younger adults. Subsequently, hospitalisations reached statistical control zones in epidemiological weeks (EW) 19-48 of 2020 (EW 19-48/2020) and EW 03-05/2021 (18-49 y, mean = 26.1%; ≥70 y, mean = 32.8%). Between EW 49/2020 and EW 02/2021, the number of hospitalisations of younger adults dropped to levels below the lower control limit. In contrast, the number of hospitalisations of older adults surpassed the upper limit of the corresponding statistical control zones. However, from EW 06/2021, numbers of hospitalisations changed from statistical control zones, with hospitalisations of younger adults increasing and reaching 44.9% in EW 24/2021 and hospitalisations of older adults decreasing until EW 19/2021 (14.1%) and reaching 17.3% in EW 24/2021. CONCLUSIONS: An increasing number of COVID-19 hospitalisations were observed in younger adults from EW 06/2021. This could be a result of the successful vaccination programme in older adults, who were initially prioritised, and possibly an increased exposure to highly transmissible variants of COVID-19 in younger adults who had to go to work in the absence of social protection (i.e. government financial support). Potential consequences of COVID-19 hospitalisations in younger adults could include a reduced life expectancy of the population and an increased number of people unable to perform daily activities due to post-COVID-19 conditions.

Three easy fixes for sire use can enhance genetic progress in community-based breeding programmes.

We analysed options to optimize the use of sires in sheep and goat community-based breeding programmes (CBBP) for three scenarios occurring under field conditions: premature sale of selection candidates, fixed service periods of selected sires and incomplete sire pedigrees. The first scenario was studied by looking at the outcome of combinations of selection pressures in successive selection stages. A compromise of early sale of sire candidates and genetic progress can be obtained by selecting in two stages, such that selection pressure in the first stage is chosen in terms of achieving an acceptable selection potential after the second stage. Simulations showed the dependency of this compromise on selection accuracies and correlation between selection criteria. For a typical sheep CBBP, only 20% of the top three months weighting male lambs need to be retained to achieve 80% of the potential selection differential on six months weight. For the second scenario, two alternatives to fixed service periods were analysed. When across-age BLUP EBVs are not available, individual sires can be programmed to stay in service according to their initial ranking. In typical sheep, CBBPs genetic progress can be increased by about 9% over response to selection with optimum fixed sire service periods. When BLUP EBVs are available, a simulated retrospective analyses of across-age selection of sires in two current sheep CBBPs increased more than twofold the average breeding values actually observed. Thirdly, we studied the benefit of considering possible sires and their mating probabilities when estimating BLUP breeding values instead of setting such sires as unknown. In a current goat CBBP with up to three possible sires included in the pedigree, the accuracy of breeding values nears the accuracy when sires are known and are higher than accuracies when sires are unknown or when possible sires are ignored.

Adjustments in population and reproductive dynamics of native and non-native congeneric species during 26 years after invasion

We aimed to improve the understanding of the establishment of Serrasalmus marginatus (non-native), which was followed by a decrease in the abundance of Serrasalmus maculatus (native) in the upper Paraná River floodplain. We estimated age, mortality rate, length and age at first maturity and variations in gonad development in three time-periods along a 26-year truncated time scale for both species. Population and reproduction parameters of both species showed substantial fluctuations among periods. Most age classes were sampled in all time-periods, but with considerable difference in abundance, with predominance of older individuals in the second time-period and younger individuals in the third time-period for both species. The mortality rates decreased for both species in the second time-period, but increased for the native in the third time-period. Length and age at first maturity decreased in the second time-period for both species, increasing the number of mature individuals on their populations. In the third time-period, the number of immature individuals increased for both species. We suggest that species experienced stressful conditions during cooccurrence and this have resulted in physiological responses in both species, reflecting in population and reproductive adjustments that may have relaxed competitive interactions between them, optimizing survival, reproductive effort and coexistence.(AU)

Nosso objetivo foi aumentar o conhecimento sobre o estabelecimento de Serrasalmus marginatus (não nativa), que foi seguido pela diminuição na abundância de Serrasalmus maculatus (nativa) na planície de inundação do alto rio Paraná. Estimamos a idade, taxa de mortalidade, comprimento e idade de primeira maturação e variações no desenvolvimento gonadal em três períodos ao longo de 26 anos para as espécies. Os parâmetros populacionais e de reprodução das espécies mostraram flutuações substanciais. A maioria das faixas etárias foi amostrada em todos os períodos, mas com diferenças consideráveis na abundância, predominando indivíduos mais velhos no segundo período e indivíduos mais jovens no terceiro período para ambas as espécies. A taxa de mortalidade diminuiu para as espécies no segundo período, mas aumentou para a espécie nativa no terceiro período. O comprimento e a idade de primeira maturação diminuíram no segundo período para as espécies, aumentando o número de indivíduos adultos. No terceiro período, o número de indivíduos imaturos aumentou para ambas as espécies. Sugerimos que as espécies passaram por condições estressantes durante a coocorrência, resultando em respostas fisiológicas que desencadearam ajustes populacionais e reprodutivos que podem ter minimizado a interação competitiva entre elas, otimizando a sobrevivência, o esforço reprodutivo e a coexistência.(AU)

Adjustments in population and reproductive dynamics of native and non-native congeneric species during 26 years after invasion

We aimed to improve the understanding of the establishment of Serrasalmus marginatus (non-native), which was followed by a decrease in the abundance of Serrasalmus maculatus (native) in the upper Paraná River floodplain. We estimated age, mortality rate, length and age at first maturity and variations in gonad development in three time-periods along a 26-year truncated time scale for both species. Population and reproduction parameters of both species showed substantial fluctuations among periods. Most age classes were sampled in all time-periods, but with considerable difference in abundance, with predominance of older individuals in the second time-period and younger individuals in the third time-period for both species. The mortality rates decreased for both species in the second time-period, but increased for the native in the third time-period. Length and age at first maturity decreased in the second time-period for both species, increasing the number of mature individuals on their populations. In the third time-period, the number of immature individuals increased for both species. We suggest that species experienced stressful conditions during cooccurrence and this have resulted in physiological responses in both species, reflecting in population and reproductive adjustments that may have relaxed competitive interactions between them, optimizing survival, reproductive effort and coexistence.(AU)

Nosso objetivo foi aumentar o conhecimento sobre o estabelecimento de Serrasalmus marginatus (não nativa), que foi seguido pela diminuição na abundância de Serrasalmus maculatus (nativa) na planície de inundação do alto rio Paraná. Estimamos a idade, taxa de mortalidade, comprimento e idade de primeira maturação e variações no desenvolvimento gonadal em três períodos ao longo de 26 anos para as espécies. Os parâmetros populacionais e de reprodução das espécies mostraram flutuações substanciais. A maioria das faixas etárias foi amostrada em todos os períodos, mas com diferenças consideráveis na abundância, predominando indivíduos mais velhos no segundo período e indivíduos mais jovens no terceiro período para ambas as espécies. A taxa de mortalidade diminuiu para as espécies no segundo período, mas aumentou para a espécie nativa no terceiro período. O comprimento e a idade de primeira maturação diminuíram no segundo período para as espécies, aumentando o número de indivíduos adultos. No terceiro período, o número de indivíduos imaturos aumentou para ambas as espécies. Sugerimos que as espécies passaram por condições estressantes durante a coocorrência, resultando em respostas fisiológicas que desencadearam ajustes populacionais e reprodutivos que podem ter minimizado a interação competitiva entre elas, otimizando a sobrevivência, o esforço reprodutivo e a coexistência.(AU)

Reproductive biology of pequira Bryconamericus stramineus (Eigenmann, 1908) in Funil Reservoir-MG, Brazil / Biologia reprodutiva da Pequira Bryconamericus stramineus (Eigenmann, 1908) no reservatório de Funil-MG, Brasil

Abstract In order to evaluate aspects of reproductive biology of the "pequira" ( Bryconamericus stramineus) in the elevator of the Funil Dam - MG, fish capture was carried out from November 2008 to January 2009 and 317 individuals were collected. The mean standard length (SL) of the population was 4.96 cm and mean weight 1.80 g. The females had SL of 5.0 cm, while males had a SL of 4.6 cm. A sex ratio of 2.20: 1 (females: male) was observed. Our results show that 73% of the individuals analyzed were considered adults. The species presented low fecundity, mean of 470.9 oocytes per female and a mean diameter of 221.08 μm, with an increase in oocyte diameter over the evaluation period. The length of the first gonadal maturation was estimated at 5.0 cm. The results obtained in this work suggest that the reproductive cycle of the species occurs in the analyzed period. Although this species does not have migratory reproductive habits, the presence of adults in the reproductive stage was observed in the transposition area, which suggests a search for new environments for spawning.

Resumo Com o objetivo de avaliar aspectos da biologia reprodutiva da pequira Bryconamericus stramineus no elevador da represa do Funil - MG foram realizadas capturas entre os meses de novembro de 2008 a janeiro de 2009, sendo coletados 317 indivíduos. O comprimento padrão (CP) médio da população foi de 4,96 cm e peso médio de 1,80 g. As fêmeas apresentaram CP de 5,0 cm, enquanto que os machos obtiveram um CP de 4,6 cm. Foi observada proporção sexual de 2,20:1(fêmeas:macho). Dos indivíduos analisados, 73% foram considerados adultos. A espécie apresentou baixa fecundidade, com média de 470,9 ovócitos por fêmea e diâmetro médio de 221,08 μm, ocorrendo aumento no diâmetro de ovócitos com o decorrer do tempo no período avaliado. O comprimento de primeira maturação gonadal foi estimado em 5,0 cm. Os resultados obtidos neste trabalho sugerem que o ciclo reprodutivo da espécie ocorre no período analisado. Embora esta espécie não tenha hábitos reprodutivos migratórios, a presença de adultos no estágio reprodutivo foi observada na área de transposição, o que sugere a busca de novos ambientes para a reprodução.

Age structure and multi-model growth estimation of longnose stingray Hypanus guttatus (Dasyatidae: Myliobatoidei) from north-east Brazil.

We collected 729 Hypanus guttatus from the northern coast of the state of Rio Grande do Norte (RN), of which 196 were used to estimate age and growth. Ninety-five were male (12.7 to 57.0 cm disc width; WD ) and 101 were female (13.0 to 88.5 cm WD ); females were significantly larger than males. Cross sections of vertebrae showed band-pairs ranging from 0 to > 14 in females and from 0 to 9 in males. New-borns presented an opaque edge at birth in vertebrae without a birthmark. The average percentage of error (APE; %E) for the entire sample provided evidence that ages were repeatable. The mean monthly marginal increment (IM ) indicates annual band-pair formation from August to November. The annual cycle model for one band-pair deposition provided the best fit to data based on the AIC, with peaks between August and October, similar to that found in the IM analysis, suggesting an annual formation pattern. A multi-model approach that included four models based on the observed mean WD at age indicated a modified von Bertalanffy growth model as the best for describing the species growth: W0 (WD at birth) = 14.6 cm for both sexes; females W∞ = 98.61 cm (95% CI = 87.34-114.61 cm); k = 0.112 year-1 (CI = 0.086-0.148 year-1 ); males W∞ = 60.22 cm (CI = 55.66-65.35 cm); k = 0.219 year-1 (CI = 0.185-0.276 year-1 ). The age-at-maturity in males and females is 5 years and 7 years, respectively. The age composition shows that most (84%) specimens were aged 0 to 2 years. The information provided here is essential for analytical assessments of H. guttatus, which is subject to significant fishing pressure mainly on new-borns and juveniles.

Reproductive biology of pequira Bryconamericus stramineus (Eigenmann, 1908) in Funil Reservoir-MG, Brazil / Biologia reprodutiva da Pequira Bryconamericus stramineus (Eigenmann, 1908) no reservatório de Funil-MG, Brasil

In order to evaluate aspects of reproductive biology of the pequira ( Bryconamericus stramineus) in the elevator of the Funil Dam - MG, fish capture was carried out from November 2008 to January 2009 and 317 individuals were collected. The mean standard length (SL) of the population was 4.96 cm and mean weight 1.80 g. The females had SL of 5.0 cm, while males had a SL of 4.6 cm. A sex ratio of 2.20: 1 (females: male) was observed. Our results show that 73% of the individuals analyzed were considered adults. The species presented low fecundity, mean of 470.9 oocytes per female and a mean diameter of 221.08 m, with an increase in oocyte diameter over the evaluation period. The length of the first gonadal maturation was estimated at 5.0 cm. The results obtained in this work suggest that the reproductive cycle of the species occurs in the analyzed period. Although this species does not have migratory reproductive habits, the presence of adults in the reproductive stage was observed in the transposition area, which suggests a search for new environments for spawning.(AU)

Com o objetivo de avaliar aspectos da biologia reprodutiva da pequira Bryconamericus stramineus no elevador da represa do Funil - MG foram realizadas capturas entre os meses de novembro de 2008 a janeiro de 2009, sendo coletados 317 indivíduos. O comprimento padrão (CP) médio da população foi de 4,96 cm e peso médio de 1,80 g. As fêmeas apresentaram CP de 5,0 cm, enquanto que os machos obtiveram um CP de 4,6 cm. Foi observada proporção sexual de 2,20:1(fêmeas:macho). Dos indivíduos analisados, 73% foram considerados adultos. A espécie apresentou baixa fecundidade, com média de 470,9 ovócitos por fêmea e diâmetro médio de 221,08 m, ocorrendo aumento no diâmetro de ovócitos com o decorrer do tempo no período avaliado. O comprimento de primeira maturação gonadal foi estimado em 5,0 cm. Os resultados obtidos neste trabalho sugerem que o ciclo reprodutivo da espécie ocorre no período analisado. Embora esta espécie não tenha hábitos reprodutivos migratórios, a presença de adultos no estágio reprodutivo foi observada na área de transposição, o que sugere a busca de novos ambientes para a reprodução.(AU)

Historias de vida y demografía de Physalaemus biligonigerus (Anura: Leptodactylidae) en una charca periurbana del centro de Argentina / Demography and life histories of Physalaemus biligonigerus (Anura: Leptodactylidae) in a peri-urban pond in central Argentina

Resumen El conocimiento de la dinámica de poblaciones provee información sobre la historia reciente, el estado actual y la tendencia futura de una población. Physalaemus biligonigerus es un anuro con una amplia distribución en el Neotrópico, presenta una actividad reproductiva elevada y explosiva, pero sus poblaciones parecen estar compuestas por individuos jóvenes. El objetivo de este estudio fue analizar la demografía poblacional de P. biligonigerus en una charca semipermanente en Río Cuarto, Córdoba, Argentina y realizar una proyección poblacional a 30 generaciones. Se determinó la estructura de edad utilizando esqueletocronología, y posteriormente se construyó una tabla de vida estática. Se calculo la fecundidad y las tasas de supervivencia para cada estadío con los que se construyó una Matriz de Leslie y se realizó la proyección poblacional. La proyección muestra oscilaciones en el número de individuos pero a pesar de esto, la tendencia final de la población es a un aumento en su tamaño. La mayor proporción de supervivientes se da en las fases de huevos a larvas, y la fuerza de mortalidad actúa con intensidad sobre la fase de larvas. La tasa neta reproductiva indica que la población de P. biligonigerus de la charca en estudio está en incremento.

Abstract Knowledge of population dynamics provides information on the recent history, current status, and future trends of a population. Physalaemus biligonigerus is widely distributed in the Neotropics, this anuran has a high and explosive reproductive activity, but its populations seem to be composed of young individuals. The objective of this study was to analyze the population demography of P. biligonigerus in a semipermanent pond in Río Cuarto, Córdoba, Argentina and to carry out a population projection through 30 generations. The age structure was determined from the use of skeletochronology, and a static life table was later made. Fertility and survival rates were calculated for each stage, by which a Leslie Matrix was constructed and the population projection was performed. The projection shows oscillations in the number of individuals but in spite of this, the final tendency of the population is an increase in its size. The highest proportion of survivors occurs in the egg-to-larval stages and the mortality force acts intensively on the larval phase. The net reproductive rate indicates that the population of P. biligonigerus of the study pond is increasing. Rev. Biol. Trop. 66(2): 765-775. Epub 2018 June 01.

Reproductive biology of pequira Bryconamericus stramineus (Eigenmann, 1908) in Funil Reservoir-MG, Brazil

Abstract In order to evaluate aspects of reproductive biology of the pequira ( Bryconamericus stramineus) in the elevator of the Funil Dam - MG, fish capture was carried out from November 2008 to January 2009 and 317 individuals were collected. The mean standard length (SL) of the population was 4.96 cm and mean weight 1.80 g. The females had SL of 5.0 cm, while males had a SL of 4.6 cm. A sex ratio of 2.20: 1 (females: male) was observed. Our results show that 73% of the individuals analyzed were considered adults. The species presented low fecundity, mean of 470.9 oocytes per female and a mean diameter of 221.08 m, with an increase in oocyte diameter over the evaluation period. The length of the first gonadal maturation was estimated at 5.0 cm. The results obtained in this work suggest that the reproductive cycle of the species occurs in the analyzed period. Although this species does not have migratory reproductive habits, the presence of adults in the reproductive stage was observed in the transposition area, which suggests a search for new environments for spawning.

Resumo Com o objetivo de avaliar aspectos da biologia reprodutiva da pequira Bryconamericus stramineus no elevador da represa do Funil - MG foram realizadas capturas entre os meses de novembro de 2008 a janeiro de 2009, sendo coletados 317 indivíduos. O comprimento padrão (CP) médio da população foi de 4,96 cm e peso médio de 1,80 g. As fêmeas apresentaram CP de 5,0 cm, enquanto que os machos obtiveram um CP de 4,6 cm. Foi observada proporção sexual de 2,20:1(fêmeas:macho). Dos indivíduos analisados, 73% foram considerados adultos. A espécie apresentou baixa fecundidade, com média de 470,9 ovócitos por fêmea e diâmetro médio de 221,08 m, ocorrendo aumento no diâmetro de ovócitos com o decorrer do tempo no período avaliado. O comprimento de primeira maturação gonadal foi estimado em 5,0 cm. Os resultados obtidos neste trabalho sugerem que o ciclo reprodutivo da espécie ocorre no período analisado. Embora esta espécie não tenha hábitos reprodutivos migratórios, a presença de adultos no estágio reprodutivo foi observada na área de transposição, o que sugere a busca de novos ambientes para a reprodução.

Reproductive biology of pequira Bryconamericus stramineus (Eigenmann, 1908) in Funil Reservoir-MG, Brazil

Abstract In order to evaluate aspects of reproductive biology of the pequira ( Bryconamericus stramineus) in the elevator of the Funil Dam - MG, fish capture was carried out from November 2008 to January 2009 and 317 individuals were collected. The mean standard length (SL) of the population was 4.96 cm and mean weight 1.80 g. The females had SL of 5.0 cm, while males had a SL of 4.6 cm. A sex ratio of 2.20: 1 (females: male) was observed. Our results show that 73% of the individuals analyzed were considered adults. The species presented low fecundity, mean of 470.9 oocytes per female and a mean diameter of 221.08 m, with an increase in oocyte diameter over the evaluation period. The length of the first gonadal maturation was estimated at 5.0 cm. The results obtained in this work suggest that the reproductive cycle of the species occurs in the analyzed period. Although this species does not have migratory reproductive habits, the presence of adults in the reproductive stage was observed in the transposition area, which suggests a search for new environments for spawning.

Resumo Com o objetivo de avaliar aspectos da biologia reprodutiva da pequira Bryconamericus stramineus no elevador da represa do Funil - MG foram realizadas capturas entre os meses de novembro de 2008 a janeiro de 2009, sendo coletados 317 indivíduos. O comprimento padrão (CP) médio da população foi de 4,96 cm e peso médio de 1,80 g. As fêmeas apresentaram CP de 5,0 cm, enquanto que os machos obtiveram um CP de 4,6 cm. Foi observada proporção sexual de 2,20:1(fêmeas:macho). Dos indivíduos analisados, 73% foram considerados adultos. A espécie apresentou baixa fecundidade, com média de 470,9 ovócitos por fêmea e diâmetro médio de 221,08 m, ocorrendo aumento no diâmetro de ovócitos com o decorrer do tempo no período avaliado. O comprimento de primeira maturação gonadal foi estimado em 5,0 cm. Os resultados obtidos neste trabalho sugerem que o ciclo reprodutivo da espécie ocorre no período analisado. Embora esta espécie não tenha hábitos reprodutivos migratórios, a presença de adultos no estágio reprodutivo foi observada na área de transposição, o que sugere a busca de novos ambientes para a reprodução.

Population structure of two species of Heliconius Kluk, 1780 butterflies (Lepidoptera: Nymphalidae) / Estrutura populacional de duas espécies de borboletas Heliconius Kluk, 1780 (Lepidoptera: Nymphalidae)

As populações de Heliconius erato phyllis (Fabricius, 1775) e Heliconius ethilla narcaea Godart, 1819 foram quantificadas em uma reserva florestal de mata semi-decídual na região central do Brasil, durante o período de um ano. As subespécies apresentaram tamanho populacional similar, mas com distintos padrões. A razão sexual foi diferente entre as subespécies: H. erato phyllis apresentou mais fêmeas e H. ethilla narcaea mais machos, na maioria dos meses. Variação sazonal no tamanho dos indivíduos foi observada em ambas as populações, entretanto, a distribuição da classe etária foi diferente entre os meses e as subespécies. Assim, os resultados desse estudo demonstraram que as populações de H. erato phyllis e H. ethilla narceae apresentam semelhanças em seu tamanho, mas com propriedades e variações mensais distintas.

The populations of Heliconius erato phyllis (Fabricius, 1775) and Heliconius ethilla narcaea Godart, 1819 were monitored in a semi-deciduous forest reserve in the central region of Brazil, during the one-year period. Both subspecies presented similar population size but distinct population patterns. The sex ratio was different between the subspecies: H. erato phyllis tending to have more females and H. ethilla narceae males, in most of the observations. Seasonal variation in the adult size was observed in both populations studied, however, the distribution of the adult age structure was different between over the months and subspecies. Thus, the results of this study demonstrated that populations of H. erato phyllis and H. ethilla narceae exhibit similar population size, but distinct properties and monthly variations.

Fenologia de Cornops aquaticum (Bruner) (Orthoptera: Acrididae) em Eichhornia azurea (Pontederiaceae) no norte do Pantanal de Mato Grosso / Phenology of Cornops aquaticum (Bruner) (Orthoptera: Acrididae) in Eichhornia azurea (Pontederiaceae) in the northern region of Pantanal of Mato Grosso, Brazil

Cornops aquaticum (Bruner) has Eichhornia crassipes, E. azurea, Pontederia cordata and P. lanceolata (Pontederiaceae) as the known host plants. This grasshopper species is cited as a possible agent of biological control for native aquatic macrophytes E. azurea and E. crassipes. This study, carried out from March, 2006 to February, 2007, aimed to evaluate the phenology and age structure of the population of C. aquaticum associated with E. azurea in Piuval bay, Pantanal of Poconé, MT, and to identify possible relationships of its life cycle to abiotic factors such as insolation, temperature and precipitation. Monthly collections of 50 individuals were carried out according to the protocol defined by the "Host - Insect Coevolution on Waterhyacinth" project. Adults and nymphs were separated and the females dissected in order to evaluate ovary maturation. The population presented adults and nymphs during the whole year, suggesting the occurrence of more than one reproductive period. The nymphs from the first stage predominated in August 2006 and the adults in September and October 2006, synchronized with the dry period and beginning of the flooding period, respectively. The highest relative abundance of the females with mature ovaries occurred in July 2006 (50 percent), indicating that this may be a more propitious period for reproduction. The data suggest that C. aquaticum is a species in continual reproduction in Piuval bay and its cycle is associated with the environmental conditions guided by the flood pulse in the Pantanal of Mato Grosso.

Fecundidade abaixo da reposição, população estacionária por migração e efeitos sobre a estrutura etária / Fecundidad por debajo de la reposición, población estacionaria por migración y efectos sobre la estructura etaria / Fertility below replacement, stationary population through migration and effects of age structures

Diante do declínio da fecundidade, o Brasil aproxima-se das condições demográficas que determinam o crescimento zero ou negativo, no longo prazo, de uma população. Entretanto, não há razões suficientes para se afirmar que a fecundidade estabilizar-se-á no nível de reposição ou pouco abaixo dele. Há indicações de que ela deve atingir patamares bastante baixos a esse nível nas próximas décadas. Teoricamente, uma população estável e fechada com taxas de fecundidade abaixo do nível de reposição pode retomar o crescimento zero se submetida a uma mudança do número anual constante de entradas derivadas do retorno da fecundidade ao nível de reposição. Isto também pode ocorrer devido a saldos líquidos migratórios positivos, constantes e com estrutura etária fixa. Portanto, para um determinado conjunto de taxas de saída existe um número infinito de populações estacionárias equivalentes. Pressupondo um regime de fecundidade abaixo da reposição, este trabalho utiliza o modelo teórico de Schmertmann (1992) para simular e examinar, comparativamente, a estrutura etária da população do Estado de São Paulo, resultante de um aumento da fecundidade até o nível de reposição, e as estruturas etárias desta mesma população tornada estacionária via migração, assumindo diferentes cenários de fecundidade e estrutura etária das imigrantes.

Ante el declive de la fecundidad, Brasil se aproxima a las condiciones demográficas que determinan el crecimiento cero o negativo, en el largo plazo, de una población. Entretanto, no hay razones suficientes para afirmar que la fecundidad se estabilizará en el nivel de reposición o un poco por debajo de él. Hay indicaciones de que ésta debe alcanzar cifras bastante bajas a ese nivel en las próximas décadas. Teóricamente, una población estable y cerrada con tasas de fecundidad por debajo del nivel de reposición puede retomar el crecimiento cero si es sometida a un cambio del número anual constante de entradas derivadas del retorno de la fecundidad al nivel de reposición. Esto también puede ocurrir debido a saldos netos migratorios positivos, constantes y con estructura etaria fija. Por lo tanto, para un determinado conjunto de tasas de salida existe un número infinito de poblaciones estacionarias equivalentes. Presuponiendo un régimen de fecundidad por debajo de la reposición, este trabajo utiliza el modelo teórico de Schmertmann (1992) para simular y examinar, comparativamente, la estructura etaria de la población del Estado de San Pablo, resultante de un aumento de la fecundidad hasta el nivel de reposición, y las estructuras etarias de esta misma población tornada estacionaria vía migración, asumiendo diferentes escenarios de fecundidad y estructura etaria de las inmigrantes.

Due to its declining fertility rate, Brazil is closer to the demographic conditions that determine population zero or negative growth, on the long run. However, there are no reasonable grounds to assert that the fertility rate will stabilize at replacement level or just below it. There are indications that it will be likely to descend to very low levels in coming decades. Theoretically, a stable and closed population with fertility rates below replacement level can return to zero growth if the population is subjected to changes in the constant annual number of entries derived from the return of fertility to replacement level. This may also occur due to constant positive net migration with constant and fixed age structure. Therefore, for a given set of rates of exits, there are an infinite number of equivalent stationary populations. Given fertility below replacement level, the present study uses Schmertmann's theoretical model (1992) to simulate and examine, by comparison, (1) the age structure of the population of the State of São Paulo, Brazil, that has resulted from a rise in fertility to replacement level and (2) the age structures of this population, as made stationary through migration, assuming different scenarios of fertility and the age structure of immigrants.

Age and growth of the Argentine hake Merluccius hubbsi Marini, 1933 in the Brazilian South-Southeast Region during 1996-2001

This is the first detailed study on the age and growth of the Argentine hake Merluccius hubbsi in Brazilian waters. A total of 3,651 specimens obtained from surveys and sampling landings using trawlers and long-lines in the South-Southeast Region (21ºS to 34ºS) between 1996 and 2001 were analyzed. Readings of sliced and burned otoliths were conducted on 686 individuals (397 females, 129 males and 160 young - sex not identified), identifying opaque and translucent zones. Marginal increment and edge type percentage methods were used for validation, resulting in one ring per year, formed during summer-autumn. Fish with no more than eight rings and six years of age were found, the two first rings after the core being formed during the first year. Back-calculation methods were applied to length/age data and the parameters of von Bertalanffy's growth model were fitted based on average length per ring. The value of maximum theoretical length varied between 470.27 mm and 807.40 mm; growth coefficient varied from 0.1657 to 0.3555 year-1 and the theoretical age at length zero between -1.2846 and -0.4552 years. Growth of females and males differed significantly. The techniques applied and the results obtained are discussed and compared with studies on hake conducted in Uruguay and Argentina, providing important information for the management of the species in Brazil, where it presents clear signs of overexploitation

Este é o primeiro estudo detalhado sobre a idade e o crescimento da merluza Merluccius hubbsi no Brasil. Foram analisados 3.651 espécimes obtidos em cruzeiros de pesquisa e provenientes das frotas de arrasto e espinhel de fundo da região Sudeste-Sul do Brasil (21ºS a 34ºS) entre 1996 e 2001. Leituras de secções transversais de otólitos (corte, polimento e queima) foram realizadas para 686 indivíduos (397 fêmeas, 129 machos e 160 jovens com sexo não identificado), identificando-se zonas opacas e translúcidas. Foram calculados o incremento marginal e a porcentagem do tipo de borda, no tempo, para validação, resultando em um anel por ano, formado durante o verão-outono. Foram obtidos peixes com até oito anéis e seis anos de idade, sendo que os dois anéis depois do núcleo se formam durante o primeiro ano de vida. Foram aplicados métodos de retrocálculo aos dados de comprimento na idade e os parâmetros do modelo de von Bertalanffy foram estimados. O valor do comprimento máximo teórico variou entre 470,27 mm e 807,40 mm; a taxa de crescimento variou de 0,1657 a 0,3555 ano-1 e a idade teórica de comprimento zero entre -1,2846 e -0,4552 anos. O crescimento de fêmeas e machos difere significativamente. As técnicas aplicadas e os resultados obtidos foram discutidos, sendo comparados com estudos realizados no Uruguai e na Argentina e provendo informação importante para a gestão da espécie no Brasil, onde a merluza apresenta claros sinais de sobrepesca

Age and growth of the Argentine hake Merluccius hubbsi Marini, 1933 in the Brazilian South-Southeast Region during 1996-2001

This is the first detailed study on the age and growth of the Argentine hake Merluccius hubbsi in Brazilian waters. A total of 3,651 specimens obtained from surveys and sampling landings using trawlers and long-lines in the South-Southeast Region (21ºS to 34ºS) between 1996 and 2001 were analyzed. Readings of sliced and burned otoliths were conducted on 686 individuals (397 females, 129 males and 160 young - sex not identified), identifying opaque and translucent zones. Marginal increment and edge type percentage methods were used for validation, resulting in one ring per year, formed during summer-autumn. Fish with no more than eight rings and six years of age were found, the two first rings after the core being formed during the first year. Back-calculation methods were applied to length/age data and the parameters of von Bertalanffy's growth model were fitted based on average length per ring. The value of maximum theoretical length varied between 470.27 mm and 807.40 mm; growth coefficient varied from 0.1657 to 0.3555 year-1 and the theoretical age at length zero between -1.2846 and -0.4552 years. Growth of females and males differed significantly. The techniques applied and the results obtained are discussed and compared with studies on hake conducted in Uruguay and Argentina, providing important information for the management of the species in Brazil, where it presents clear signs of overexploitation.

Este é o primeiro estudo detalhado sobre a idade e o crescimento da merluza Merluccius hubbsi no Brasil. Foram analisados 3.651 espécimes obtidos em cruzeiros de pesquisa e provenientes das frotas de arrasto e espinhel de fundo da região Sudeste-Sul do Brasil (21ºS a 34ºS) entre 1996 e 2001. Leituras de secções transversais de otólitos (corte, polimento e queima) foram realizadas para 686 indivíduos (397 fêmeas, 129 machos e 160 jovens com sexo não identificado), identificando-se zonas opacas e translúcidas. Foram calculados o incremento marginal e a porcentagem do tipo de borda, no tempo, para validação, resultando em um anel por ano, formado durante o verão-outono. Foram obtidos peixes com até oito anéis e seis anos de idade, sendo que os dois anéis depois do núcleo se formam durante o primeiro ano de vida. Foram aplicados métodos de retrocálculo aos dados de comprimento na idade e os parâmetros do modelo de von Bertalanffy foram estimados. O valor do comprimento máximo teórico variou entre 470,27 mm e 807,40 mm; a taxa de crescimento variou de 0,1657 a 0,3555 ano-1 e a idade teórica de comprimento zero entre -1,2846 e -0,4552 anos. O crescimento de fêmeas e machos difere significativamente. As técnicas aplicadas e os resultados obtidos foram discutidos, sendo comparados com estudos realizados no Uruguai e na Argentina e provendo informação importante para a gestão da espécie no Brasil, onde a merluza apresenta claros sinais de sobrepesca.

Marking with pigments for identification of flies in experimental populations of Megaselia scalaris Loew

The insect marking technique of Tadei & Mourão (1976) is until now the only experimental method allowing real-age determination of each individual in a population and, consequently, determination of age structure in a given population. We propose an improvement of this technique, used here to determine the population age structure of the geographical strain SR of the Megaselia scalaris Loew (Diptera; Phoridae), maintained by serial transfer technique at constant temperatures 25 ± 1.0ºC and 20 ± 1.0ºC. Determining the age structure allowed the calculation of the real longevity of the flies and the identification of the effect of temperature decisive factors in these are the technique of marking insects, because otherwise we would only have an estimate, and depending on mistakes there in, the effect of the determinant factor (temperature) cannot be detected.

A técnica de marcação de insetos de Tadei & Mourão (1976) é, até o momento, o único método experimental que possibilita determinar a idade real de cada indivíduo na população e, conseqüentemente, determinar a estrutura etária da mesma. Para isto propomos um aprimoramento dessa técnica, utilizada aqui para determinar a estrutura etária de populações da linhagem geográfica SR do díptero forídeo Megaselia scalaris Loew, mantidas pela técnica da transferência seriada em câmaras com temperatura constante de 25 ± 1,0ºC e 20 ± 1,0ºC. O estabelecimento da estrutura etária permitiu calcular a longevidade real das moscas e detectar o efeito ambiental temperatura, sendo fator determinante neste trabalho a marcação dos insetos, pois se não o fosse, teríamos somente estimativas e, dependendo do erro cometido na estimação, o efeito do fator de interesse (temperatura) poderia não ser detectado.