886 resultados para Size frequency distribution


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Ecology and dynamics of juvenile pink shrimp Penaeus duorarum were studied from weekly sampling in the Abidjan lagoon system. After a brief description of biogeography and principal features of climate, hydrology of Ebrié lagoon and Adiopodoumé bay were considered. Shrimp distribution were connected with the main environmental factors. Precise work was done in Adiopodoumé bay, especially concerning the succession of age classes, their growth on the nursery grounds, seasonal variation in abundance, size and distribution, in relation to environmental factors. These results, and former knowledges, allowed us to propose a general pattern for pink shrimp life history in Côte d'Ivoire.

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Von Bertalanffy's growth curve parameters K, L∞ and t'o have been estimated for female Penaeus duorarum by modal progression analysis, using the "successive maximums method" of Gheno and Le Guen (1968) for the polymodal size frequency curves analysis and the Tomlinson and Abrahamson's least squares method for parameters computations. For the male the authors used an original method to get an age/length key. The parameters were calculated by Gulland's graphical method (1969).

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Behavior of young (8−18 mm SL) giant trevally (Caranx ignobilis), a large coral-reef−associated predator, was observed in the laboratory and the ocean. Size was a better predictor of swimming speed and endurance than was age. Critical speed increased with size from 12 to 40 cm/s at 2.7 cm/s for each mm increase in size. Mean scaled critical speed was 19 body lengths/s and was not size related. Swimming speed in the ocean was 4 to 20 cm/s (about half of critical speed) and varied among areas, but within each area, it increased at 2 cm/s for each mm increase in size. Swimming endurance in the laboratory increased from 5 to 40 km at 5 km for each mm increase in size. Vertical distribution changed ontogenetically: larvae swam shallower, but more variably, and then deeper with growth. Two-thirds of individuals swam directionally with no ontogenetic increase in orientation precision. Larvae swam offshore off open coasts, but not in a bay. In situ observations of C. ignobilis feeding, interacting with pelagic animals, and reacting to reefs are reported. Manusc

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The population biology and status of the painted sweeplips (Diagramma pictum) and spangled emperor (Lethrinus nebulosus) in the southern Arabian Gulf were established by using a combination of size-frequency, biological, and size-at-age data. Transverse sections of sagittal otoliths were characterized by alternating translucent and opaque bands that were validated as annuli. Comparisons of growth characteristics showed that there were no significant differences (P>0.05) between sexes. There were well defined peaks in the reproductive cycle, spawning occurred from April to May for both species, and the mean size at which females attained sexual maturity was 31.8 cm fork length (LF) for D. pictum and 27.6 cm (LF) for L. nebulosus. The mean sizes at first capture (21.1 cm LF for D. pictum and 26.4 cm LF for L. nebulosus) were smaller than the sizes for both at first sexual maturity and those at which yield per recruit would be maximized. The range of fishing-induced mortality rates for D. pictum (0.37−0.62/yr) was substantially greater than the target (Fopt=0.07/yr) and limit (Flimit=0.09/ yr) estimates. The range of fishing-induced mortality rates for L. nebulosus (0.15/yr to 0.57/yr) was also in excess of biological reference points (Fopt=0.10/yr and Flimit=0.13/yr). In addition to growth overfishing, the stocks were considered to be recruitment overfished because the biomass per recruit was less than 20% of the unexploited levels for both species. The results of the study are important to fisheries management authorities in the region because they indicate that both a reduction in fishing effort and mesh-size regulations are required for the demersal trap fishery.

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O presente estudo tem como objetivo geral traçar um perfil das escolhas léxico-gramaticais da escrita em inglês de um grupo de aprendizes brasileiros na cidade do Rio de Janeiro, ao longo dos anos de 2009 a 2012, através da análise de sua produção de quadrigramas (ou blocos de quatro itens lexicais usados com frequência por vários aprendizes) em composições escritas como parte da avaliação final de curso. Como objetivo específico, a pesquisa pretendeu analisar se os quadrigramas produzidos estavam dentre aqueles que haviam sido previamente ensinados para a execução da redação ou se pertenceriam a alguma outra categoria, isto é, quadrigramas já incorporados ao uso da língua ou quadrigramas errôneos usados com abrangência pela população investigada. Para tal, foram coletadas composições escritas por aprendizes de mesmo nível de proficiência de várias filiais de um mesmo curso livre de inglês na cidade do Rio de Janeiro. Em seguida, essas composições foram digitadas e anotadas para constituírem um corpus digital facilmente identificável em termos do tipo e gênero textual, perfil do aprendiz, filial e área de origem do Rio de Janeiro. O estudo faz uso de preceitos e métodos da Linguística de Corpus, área da Linguística que compila grandes quantidades de textos e deles extrai dados com o auxílio de um programa de computador para mapear uso, frequência, distribuição e abrangência de determinados fenômenos linguístico ou discursivo. O resultado demonstra que os aprendizes investigados usaram poucos quadrigramas ensinados e, coletivamente, preferiram usar outros que não haviam sido ensinados nas aulas específicas para o nível cursado. O estudo também demonstrou que quando o gênero textual faz parte de seu mundo pessoal, os aprendizes parecem utilizar mais quadrigramas previamente ensinados. Isto pode querer dizer que o gênero pode influenciar nas escolhas léxico-gramaticais corretas. O estudo abre portas para se compreender a importância de blocos léxico-gramaticais em escrita em L2 como forma de assegurar fluência e acuracidade no idioma e sugere que é preciso proporcionar maiores oportunidades de prática e conscientização dos aprendizes quanto ao uso de tais blocos

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Length-weight relationships (LWR) of 76 fish populations, distributed among 11 families, 18 genera and 22 species, inhabiting coastal (marine/brackish water ) ecosystems in Nigeria were estimated (39 cases) or assembled from the literature (37 cases). The mean exponent (b = 2.912) is significantly less than 3. While the frequency distribution of a was positively skewed, that of b was approximately normal. The mean a and b data are also presented by fish genera and families.

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Length-based methods (LBMs) were used to study the growth of Trisopterus minutus capelanus in the Strait of Sicily (Messina Strait). A total of 16,304 'merluzzetto' or poor cod collected by experimental trawling off the southern coast of Sicily during spring, summer, autumn 1986 and winter 1987 were measured in order to estimate the length structure of the population. Length-frequency distribution were analyzed and normal components were discriminated. Von Bertalanffy growth parameters were derived from the mean length of the normal components. The growth parameters obtained by weighted non-linear regression were: K=0.462 (yr super(1)), L sub( infinity )=222.3 (TL,mm) and t sub(o)=-0.679 yr. The resulting growth performance index ( Phi ') was 4.36, a value slightly lower than those derived for Western Mediterranean (mean Phi '=4.45) and Adriatic ( Phi '=4.58) populations and slightly higher than that derived for Hellenic waters ( Phi '=4.27). On the basis of the von Bertalanffy parameters estimated, an array of age-specific instantaneous natural mortality rate (M sub(t)=0.5-1.1) and an average value of total natural mortality rate (Z=2.1 yr super(1)) were estimated and used in the Thompson and Bell yield per recruit (Y/R) analysis in order to evaluate the status of the fishery and forecast the effects of changes in the fishing pattern. Results indicate that this resource is overexploited and that Y/R could be increased by postponing the age at first capture from 0.5 to 1.0 yr. Even a slight reduction in fishing mortality could improve the performance of the fishery. At the present level of exploitation, and assuming a constant recruitment, the spawning stock biomass per recruit (SPR) is well below the conservative threshold of 30% of the pristine or unexploited SPR.

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Long-term trends in the elasmobranch assemblage of Elkhorn Slough, Monterey Bay, California, were analyzed by documenting species composition and catch per unit effort (CPUE) from 55 sport fishing derbies that occurred during May, June, and July, from 1951 until 1995. The most abundant species (bat ray, Myliobatis californica; shovelnose guitarfish, Rhinobatos productus; and leopard shark, Triakis semifasciata) were also analyzed for size-weight relationships, trends in size class distribution, stage of maturity, and sex ratios. Changes in species composition over the course of the derbies included the near complete disappearance of shovelnose guitarfish by the 1970’s and a slight increase in the abundance of minor species (mainly smoothhounds, Mustelus spp., and thornback, Platyrhinoidis triseriata) starting in the mid 1960’s. The relative abundance of bat rays in the catch steadily increased over the years while the relative abundance of leopard sharks declined during the last two decades. However the average number of bat rays and leopard sharks caught per derby declined during the last two decades. Fishing effort appeared to increase over the course of the derbies. There were no dramatic shifts in the size class distribution data for bat rays, leopard sharks, or shovelnose guitarfish. The catch of bat rays and leopard sharks was consistently dominated by immature individuals, while the catch of shovelnose guitarfish was heavily dominated by adults. There was evidence of sexual segregation in either immature or mature fish in all the species. Female bat rays and shovelnose guitarfish were larger than their male counterparts and outnumbered males nearly 2:1. Female and male leopard sharks were more nearly equal in size and sex ratio. Changes in species composition are likely due to fishing pressure, shifts in the prevailing oceanographic conditions, and habitat alteration in Elkhorn Slough. The sex ratios, stage of maturity, and size class distributions provide further evidence for the theory that Elkhorn Slough functions as a nursery habitat for bat rays and leopard sha

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ABSTRACT TRANSCRIBED FROM ENGLE'S PH.D. ORAL DEFENSE PAMPHLET: The natural history of juvenile California spiny lobster, Panulirus interruptus (Randall), was investigated, with primary emphasis placed on ascertaining juvenile habitats, determining juvenile growth rates and component growth processes, and evaluating ecological and behavioral phenomena associated with juvenile survival and growth. Habitat surveys of island and mainland localities throughout southern and lower California revealed that small, greenish juveniles typically inhabit crevices or temporary burrows in 0-4m deep, wave-swept rocky habitats covered by dense beds of surf grass, Phyllospadix torreyi S. Watson. Phyllospadix beds were more abundant on gradually sloping rocky mainland beaches than on steeply sloping island shores. Phyllospadix abundance was positively correlated with P. interruptus abundance; however, at Santa Catalina Island, the Phyllospadix habitat was not extensive enough to be the sole lobster nursery. In laboratory tests, puerulus larvae and early juveniles chose Phyllospadix over rubble rocks or broad-bladed kelp, but did not consistently prefer Phyllospadix over reticulate algae. Ecology, growth, and behavior of juvenile P. interruptus inhabiting a discrete Phyllospadix habitat at Bird Rock, Santa Catalina Island, were investigated from October 1974 through December 1976 by means of frequent scuba surveys. Pueruli settled from June to November. Peak recruitment occurred from July to September, when seasonal temperatures were maximal. Settled larvae were approximately one year old. Juvenile growth was determined by size-frequency, single molt increment, mark-recapture, and laboratory culture studies. Carapace length vs. wet weight relationships fit standard power curve equations. Bird Rock juveniles grew from 7 to 32mm CL in 10-11 molts and from 32 to 56mm CL in 5-6 molts during their first and second benthic years, respectively. Growth rates were similar for males and females. Juveniles regenerating more than two limbs grew less per molt than intact lobsters. Long-term growth of laboratory-reared juveniles was 20% less than that of field lobsters. Growth component multiple regression analyses demonstrated that molt increment was directly proportional to premolt size and temperature for age 1+ lobsters. Molt frequency was inversely proportional to size and directly proportional to temperature. Temperature affected age 2+ lobsters similarly, but molt increment was independent of size, and molt frequency declined at a different rate. Juvenile growth rates more than doubled during warm water months compared to cold water months, primarily because of increased molt frequency. Based on results from this study and from previous investigations, it is estimated that P. interruptus males and females become sexually mature by ages 4 and 5 years, respectively, and that legai size is reached by 7 or 8 years of age. Juvenile P. interruptus activity patterns and foraging behavior were similar to those of adults, except that juvenile home ranges were proportionally smaller, and small juveniles were apparently not attracted to distant food. Small mollusks, abundant in Phyllospadix habitats, were the major food items. Size-dependent predation by fish and octopus apparently caused the considerable juvenile mortality observed at Bird Rock. Juveniles approaching 2 years of age gathered in mixed size-class aggregations by day and foraged beyond the grass beds at night. In autumn, these juveniles migrated to deeper habitats, coincident with new puerulus settlement in the Phyllospadix beds. Based on strong inferences from the results, it is proposed that size-dependent predation is the most important factor determining the !ife history strategy of juvenile P. interruptus. Life history tactics promoting rapid growth apparently function dually in reducing the period of high vulnerability to predation and decreasing the time required to reach sexual maturity. The Phyllospadix habitat is an excellent lobster nursery because it provides shelter from predators and possesses abundant food resources for sustaining optimum juvenile growth rates in shallow, warm water.

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O ambiente universitário é um espaço estratégico para a promoção da alimentação saudável e da segurança alimentar e nutricional, pois muitos hábitos alimentares adquiridos pelos estudantes se mantêm na idade adulta. No Brasil, nos últimos anos, esse ambiente passou a ser ainda mais estratégico, uma vez que incorporou medidas de ação afirmativa (sistema de cotas) e de permanência dos estudantes. O objetivo desse estudo foi avaliar o impacto da implementação do Restaurante Universitário (RU) na alimentação de estudantes de uma universidade pública brasileira. Seus resultados estão apresentados na forma de dois artigos. O primeiro objetivou descrever as práticas alimentares de estudantes do campus Maracanã da UERJ antes da implementação do RU e examiná-las segundo sua forma de ingresso na universidade (cotistas e não cotistas). No segundo semestre de 2011, foi realizado um estudo seccional com o universo de estudantes ingressantes no primeiro semestre daquele ano. Utilizou-se questionário autopreenchido e identificado que abarcou os hábitos de realizar desjejum e de substituir o almoço e/ou o jantar por lanche regularmente (≥ 5 dias/semana) e o consumo regular (≥ 5 dias/semana) de alimentos marcadores de alimentação saudável e não saudável. Participaram do estudo 1336 estudantes. Foram descritas e comparadas a distribuição da frequência semanal dessas práticas e, também, a proporção de estudantes que realizaram essas práticas em pelo menos cinco dias na semana que antecedeu o estudo. Foram observadas proporções expressivas de: não realização do desjejum, substituição do jantar por lanche, baixo consumo de frutas, hortaliças e feijão e consumo frequente de bebidas açucaradas, guloseimas e biscoitos e/ou salgadinhos de pacote. Entre cotistas, foi mais frequente o consumo de feijão, de biscoitos e/ou salgadinhos de pacote e de biscoitos doces e menos frequentes a substituição de jantar por lanche e o consumo de hortaliças e de frutas. Cotistas e não cotistas apresentaram práticas alimentares com algumas semelhanças e desfavoráveis para a saúde. As diferenças observadas entre os dois grupos foram, em sua maioria, na direção de um quadro mais desfavorável para os cotistas, exceto para o feijão. O segundo artigo objetivou avaliar o impacto da implementação do RU sobre as práticas alimentares dos estudantes segundo forma de ingresso na universidade. Para isso, entre os meses de dezembro de 2012 e março de 2013, os estudantes responderam outra vez o questionário autopreenchido no baseline complementado com questões sobre utilização do RU (n= 1131). A variação das práticas alimentares foi examinada pela diferença entre proporções obtidas antes e depois da implementação do RU e pela trajetória individual de cada estudante em relação às práticas estudadas. Foi observada associação entre maior assiduidade ao RU e maior frequência de consumo regular de feijão, hortaliças, hortaliças cruas, hortaliças cozidas e frutas e, também, menor frequência de consumo regular de batata frita e/ou salgados fritos e de biscoitos e/ou salgadinhos de pacote. Quando comparados aos demais, os usuários assíduos tiveram maior chance de trajetória positiva para realização do almoço, do jantar e consumo de feijão, hortaliças, hortaliças cruas, frutas e guloseimas e menor chance de trajetória negativa para consumo de feijão, hortaliças cruas, batata frita e/ou salgados fritos. Cotistas assíduos ao RU apresentaram resultados favoráveis para consumo de feijão, hortaliças, hortaliças cruas, biscoitos e/ou salgadinhos de pacote e batata frita e/ou salgados fritos e não cotistas assíduos ao RU, para consumo de feijão, hortaliças cruas, embutidos e guloseimas. A implementação do RU promoveu a melhoria na alimentação dos estudantes assíduos ao RU.

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A reação álcali-agregado - RAA é uma patologia de ação lenta que tem sido observada em construções de concreto capaz de comprometer suas estruturas. Sabe-se que a reação álcali-agregado é um fenômeno bastante complexo em virtude da grande variedade de rochas na natureza que são empregadas como agregados no preparo do concreto, podendo cada mineral utilizado afetar de forma distinta a reação ocorrida. Em função dos tipos de estrutura, das suas condições de exposição e dos materiais empregados, a RAA não se comporta sempre da mesma forma, em virtude disto a pesquisa constante neste tema é necessária para o meio técnico e a sociedade. Pesquisas laboratoriais, empíricas e experimentais tem sido rotina em muitos dos estudos da RAA dada ainda à carência de certas definições mais precisas a respeito dos métodos de ensaio, mas também em função da necessidade do melhor conhecimento dos materiais de uso em concretos como os agregados, cimentos, adições, aditivos entre outros e do comportamento da estrutura. Embora técnicas de prevenção possam reduzir significativamente a incidência da RAA, muitas estruturas foram construídas antes que tais medidas fossem conhecidas, havendo no Brasil vários casos de estruturas afetadas, sendo custosos os reparos dessas estruturas. Em estudos recentes sobre o tamanho das partículas de álcali-agregado e sua distribuição foi concluído que o tamanho do agregado está relacionado com o potencial danoso da RAA. Existem ainda indícios de que o tamanho e a distribuição dos poros do concreto também sejam capazes de influenciar o potencial reativo do concreto. Neste trabalho desenvolvemos um Sistema de Visão Artificial (SVA) que, com o uso de técnicas de Processamento de Imagens, é capaz de identificar em imagens de concreto, agregado e poros que atendam em sua forma, às especificações do usuário, possibilitando o cálculo da porosidade e produzindo imagens segmentadas à partir das quais será possível extrair dados relativos à geometria desses elementos. Serão feitas duas abordagens para a obtenção das imagens, uma por Escâner Comercial, que possui vantagens relacionadas à facilidade de aquisição do equipamento, e outra por micro tomógrafo. Uma vez obtidas informações sobre as amostras de concreto, estas podem ser utilizadas para pesquisar a RAA, comparar estruturas de risco com estruturas antigas de forma a melhorar a previsão de risco de ocorrência, bem como serem aplicadas a outras no estudo de outras patologias do concreto menos comuns no nosso país, como o efeito gelo/degelo.

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Coral reefs are damaged by natural disturbances and local and global anthropogenic stresses. As stresses intensify, so do debates about whether reefs will recover after significant damage. True headway in this debate requires documented temporal trajectories for coral assemblages subjected to various combinations of stresses; therefore, we report relevant changes in coral assemblages at Little Cayman Island. Between 1999 and 2012, spatiotemporal patterns in cover, densities of juveniles and size structure of assemblages were documented inside and outside marine protected areas using transects, quadrats and measurements of maximum diameters. Over five years, bleaching and disease caused live cover to decrease from 26% to 14%, with full recovery seven years later. Juvenile densities varied, reaching a maximum in 2010. Both patterns were consistent within and outside protected areas. In addition, dominant coral species persisted within and outside protected areas although their size frequency distributions varied temporally and spatially. The health of the coral assemblage and the similarity of responses across levels of protection suggested that negligible anthropogenic disturbance at the local scale was a key factor underlying the observed resilience.

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The gonads of Otolithes cuvieri and Johnius elongatus are described in seven maturity stages. O. Cuvieri spawns once a year from April to September as evidence by ova diameter frequency distribution and GSI values. 50% maturity is attained at 210mm TL in males and 200mm TL in females. Fecundity ranged from 2387 to 104379 with a mean value of 33502. Log-Log relationship between fecundity and total lenght, body weight and ovary weight were determined. An overall sex ratio of 1.54:1.00 was unequal in favour of males. Johnius elongatus spawns twice a year from January-February to Aprile-May and from August to October as evidence by ova diameter frequency distribution and GSI values. 50% maturity is attained at 140-143mm TL in both sexes. Fecundity ranged from 4238 to 167669 with a mean value of 42818. Log-Log relationship between fecundity and total lenght, body weign and ovary weight were determined. An overall sex ratio of 1.00:1.20 was unequal in favour of females.

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An investigation on length-weight relationship, length-frequency distribution, catch per unit of effort (CPUE) and stocking and harvesting status of three Indian major carps: rohu Labeo rohita, catla Catla catla and mrigal Cirrhinus mrigala and three exotic carps: silver carp Hypophthalmichthys molitrix, grass carp Ctenopharyngodon idella) and common carp Cyprinus carpio was carried out in Nasti baor (oxbow lake) for the harvesting season from August to December 1995. The length-weight relationship for six carp species was established for the harvesting months of November and December 1995. The b values for different species respectively for the months of November and December were 2.95 and 2.58 for rohu, 3.06 and 2.98 for catla, 2,84 and 2.90 for mrigal, 2.75 and 2.60 for silver carp, 2.51 and 1.97 for grass carp and 2.38 and 2.50 for common carp. In CPUE study, the CPUE was 0.58 kg/ha/hr while the catch per gear was 0.08 kg/ha/hr/purse-seine. The recovery percentage of mrigal was highest (63.57%) and it was lowest (16.81%) in case of silver carp. The density of submerged macrophytes (Hydrilla, Utricularia, Ceratophyllum and Vallisneria) was highest (4.39 kg/sqm) in November and was lowest (0.76 kg/sqm) in September.