Influence of urbanization on stream fish assemblages in three microbasins in the Upper Paraná River Basin / Influência da urbanização em assembleias de peixes de riachos em três microbacias na bacia do Alto Rio Paraná

Abstract The colonization pattern of fish assemblages in streams is often studied in the context of environmental filters. On the other hand, when fish assemblages are subjected to anthropogenic effects, variables associated with environmental quality assume more importance. Therefore, this work evaluated the richness and composition of fish from streams sampled at different urbanization levels, aiming to determine any direct effects on the structure of fish assemblages. To accomplish this, samples were collected from 2003 to 2011 at 31 sites distributed among 3 microbasins in the Rio Ivinhema Basin, Alto Rio Paraná. Based on environmental variables, physicochemical of the water and analysis of the use and occupation of the soil, the microbasins were classified into different urbanization levels (low, medium and high). A total of 4,320 individuals were sampled, out of which 57 fish species were recorded. Sampled sites with medium urbanization level presented higher richness compared to sampled sites with high urbanization level which presented lower richness. Species richness in these sites was explained mainly by water temperature and water velocity. Results confirmed that urbanization does directly affect environmental integrity, which, in turn, can lead to the homogenization of stream assemblages.

Resumo Estudos sobre assembleias de peixes em riachos enfatizam o papel dos filtros ambientais associados ao padrão de colonização das assembleias, por outro lado, quando a assembleia está sujeita aos efeitos antropogênicos, as variáveis ambientais associadas à qualidade ambiental assumem maior importância. Dessa forma, o objetivo deste estudo foi analisar a riqueza e a composição de peixes de riachos amostrados em diferentes níveis de urbanização, buscando evidenciar se o efeito reflete diretamente na estrutura das assembleias. As amostragens foram realizadas em 31 locais distribuídos em três microbacias na bacia Rio Ivinhema, Alto Rio Paraná, no período de 2003 a 2011. Com base nas variáveis ambientais, físico-químicos da água e análise do uso e ocupação do solo as microbacias foram classificadas em diferentes níveis de urbanização (baixo, médio e alto). Foram amostrados um total 4.320 indivíduos, dos quais foram registradas 57 espécies de peixes. Os locais amostrados com influência média da urbanização apresentaram maior riqueza de espécies, entretanto, os locais amostrados com alta influência da urbanização apresentaram menor riqueza de espécies. Dessa forma, constatamos que a urbanização influencia diretamente na integridade ambiental, que pode levar a homogeneização das assembleias de riachos.

Influence of urbanization on stream fish assemblages in three microbasins in the Upper Paraná River Basin / Influência da urbanização em assembleias de peixes de riachos em três microbacias na bacia do Alto Rio Paraná

The colonization pattern of fish assemblages in streams is often studied in the context of environmental filters. On the other hand, when fish assemblages are subjected to anthropogenic effects, variables associated with environmental quality assume more importance. Therefore, this work evaluated the richness and composition of fish from streams sampled at different urbanization levels, aiming to determine any direct effects on the structure of fish assemblages. To accomplish this, samples were collected from 2003 to 2011 at 31 sites distributed among 3 microbasins in the Rio Ivinhema Basin, Alto Rio Paraná. Based on environmental variables, physicochemical of the water and analysis of the use and occupation of the soil, the microbasins were classified into different urbanization levels (low, medium and high). A total of 4,320 individuals were sampled, out of which 57 fish species were recorded. Sampled sites with medium urbanization level presented higher richness compared to sampled sites with high urbanization level which presented lower richness. Species richness in these sites was explained mainly by water temperature and water velocity. Results confirmed that urbanization does directly affect environmental integrity, which, in turn, can lead to the homogenization of stream assemblages.

Estudos sobre assembleias de peixes em riachos enfatizam o papel dos filtros ambientais associados ao padrão de colonização das assembleias, por outro lado, quando a assembleia está sujeita aos efeitos antropogênicos, as variáveis ambientais associadas à qualidade ambiental assumem maior importância. Dessa forma, o objetivo deste estudo foi analisar a riqueza e a composição de peixes de riachos amostrados em diferentes níveis de urbanização, buscando evidenciar se o efeito reflete diretamente na estrutura das assembleias. As amostragens foram realizadas em 31 locais distribuídos em três microbacias na bacia Rio Ivinhema, Alto Rio Paraná, no período de 2003 a 2011. Com base nas variáveis ambientais, físico-químicos da água e análise do uso e ocupação do solo as microbacias foram classificadas em diferentes níveis de urbanização (baixo, médio e alto). Foram amostrados um total 4.320 indivíduos, dos quais foram registradas 57 espécies de peixes. Os locais amostrados com influência média da urbanização apresentaram maior riqueza de espécies, entretanto, os locais amostrados com alta influência da urbanização apresentaram menor riqueza de espécies. Dessa forma, constatamos que a urbanização influencia diretamente na integridade ambiental, que pode levar a homogeneização das assembleias de riachos.

Influence of urbanization on stream fish assemblages in three microbasins in the Upper Paraná River Basin

Abstract The colonization pattern of fish assemblages in streams is often studied in the context of environmental filters. On the other hand, when fish assemblages are subjected to anthropogenic effects, variables associated with environmental quality assume more importance. Therefore, this work evaluated the richness and composition of fish from streams sampled at different urbanization levels, aiming to determine any direct effects on the structure of fish assemblages. To accomplish this, samples were collected from 2003 to 2011 at 31 sites distributed among 3 microbasins in the Rio Ivinhema Basin, Alto Rio Paraná. Based on environmental variables, physicochemical of the water and analysis of the use and occupation of the soil, the microbasins were classified into different urbanization levels (low, medium and high). A total of 4,320 individuals were sampled, out of which 57 fish species were recorded. Sampled sites with medium urbanization level presented higher richness compared to sampled sites with high urbanization level which presented lower richness. Species richness in these sites was explained mainly by water temperature and water velocity. Results confirmed that urbanization does directly affect environmental integrity, which, in turn, can lead to the homogenization of stream assemblages.

Resumo Estudos sobre assembleias de peixes em riachos enfatizam o papel dos filtros ambientais associados ao padrão de colonização das assembleias, por outro lado, quando a assembleia está sujeita aos efeitos antropogênicos, as variáveis ambientais associadas à qualidade ambiental assumem maior importância. Dessa forma, o objetivo deste estudo foi analisar a riqueza e a composição de peixes de riachos amostrados em diferentes níveis de urbanização, buscando evidenciar se o efeito reflete diretamente na estrutura das assembleias. As amostragens foram realizadas em 31 locais distribuídos em três microbacias na bacia Rio Ivinhema, Alto Rio Paraná, no período de 2003 a 2011. Com base nas variáveis ambientais, físico-químicos da água e análise do uso e ocupação do solo as microbacias foram classificadas em diferentes níveis de urbanização (baixo, médio e alto). Foram amostrados um total 4.320 indivíduos, dos quais foram registradas 57 espécies de peixes. Os locais amostrados com influência média da urbanização apresentaram maior riqueza de espécies, entretanto, os locais amostrados com alta influência da urbanização apresentaram menor riqueza de espécies. Dessa forma, constatamos que a urbanização influencia diretamente na integridade ambiental, que pode levar a homogeneização das assembleias de riachos.

Photoacoustic for thermal diffusivity determination of fish scale: A methodology for environmental integrity monitoring.

In this work the thermal diffusivity (D) of Astyanax lacustris fish scale is investigated aiming to use it for environmental integrity certification. The D values were obtained by a relatively simple procedure by a photoacoustic method. The chosen fish species is from wide occurrence in Brasil's basins. It has short migration, and it has also been used as environmental bioindicator. The results obtained in 195 scales sampled from three different streams in the Midwest region in Brazil gives an average value of D ~ 4 × 10-3 cm2/s. ANCOVA analysis demonstrated that D values are able to differentiate among the three basins and indicates that it is dependent on the scales thickness and water conductivity. This last one is strongly affected by biotic and abiotic actions, so that D values measured by photoacoustic method can be used for interpreting the environmental integrity from where the fishes were sampled.

Influence of urbanization on stream fish assemblages in three microbasins in the Upper Paraná River Basin.

The colonization pattern of fish assemblages in streams is often studied in the context of environmental filters. On the other hand, when fish assemblages are subjected to anthropogenic effects, variables associated with environmental quality assume more importance. Therefore, this work evaluated the richness and composition of fish from streams sampled at different urbanization levels, aiming to determine any direct effects on the structure of fish assemblages. To accomplish this, samples were collected from 2003 to 2011 at 31 sites distributed among 3 microbasins in the Rio Ivinhema Basin, Alto Rio Paraná. Based on environmental variables, physicochemical of the water and analysis of the use and occupation of the soil, the microbasins were classified into different urbanization levels (low, medium and high). A total of 4,320 individuals were sampled, out of which 57 fish species were recorded. Sampled sites with medium urbanization level presented higher richness compared to sampled sites with high urbanization level which presented lower richness. Species richness in these sites was explained mainly by water temperature and water velocity. Results confirmed that urbanization does directly affect environmental integrity, which, in turn, can lead to the homogenization of stream assemblages.

Reproduction of Hypoptopoma inexspectatum (Holmberg, 1893) (Siluriformes, Loricariidae) in the Southern Pantanal Floodplain, Upper Paraguay River Basin, Brazil.

This work aimed to describe the reproductive biology of Hypoptopoma inexspectatum in southern Pantanal. A total of 538 individuals were sampled and analyzed from February 2009 through January 2011 in southern Pantanal. We did not observe differences in sex-ratio, and both sexes presented positive allometric length/weight relationship (LWR). Reproduction occurs mainly from January to February. Females reached first maturation (L50) with 37.80 mm and males with 45.80 mm. Absolute fecundity is estimated in mean=177.43 (sd±127.06) oocytes and relative fecundity in 3.12 (sd±2.23) oocytes/mg. Fecundity is positively correlated with standard length (Spearman r= 0.43; p=0.013), and total spawning is a used spawning strategy for H. inexspectatum.

Reproduction of Hypoptopoma inexspectatum (Holmberg, 1893) (Siluriformes, Loricariidae) in the Southern Pantanal floodplain, upper Paraguay River basin, Brazil / Reprodução de Hypoptopoma inexspectatum (Holmberg, 1893) (Siluriformes, Loricariidae) na planície de inundação do Pantanal Sul, bacia do alto rio Paraguai, Brasil

This work aimed to describe the reproductive biology of Hypoptopoma inexspectatum in southern Pantanal. A total of 538 individuals were sampled and analyzed from February 2009 through January 2011 in southern Pantanal. We did not observe differences in sex-ratio, and both sexes presented positive allometric length/weight relationship (LWR). Reproduction occurs mainly from January to February. Females reached first maturation (L50) with 37.80 mm and males with 45.80 mm. Absolute fecundity is estimated in mean=177.43 (sd±127.06) oocytes and relative fecundity in 3.12 (sd±2.23) oocytes/mg. Fecundity is positively correlated with standard length (Spearman r= 0.43; p=0.013), and total spawning is a used spawning strategy for H. inexspectatum.

Este trabalho teve como objetivo descrever a biologia reprodutiva de Hypoptopoma inexspectatum na região do Pantanal Sul. Foram amostrados e analisados entre fevereiro de 2009 a janeiro de 2011 um total de 538 indivíduos. Não foi observada diferença na proporção sexual e ambos os sexos apresentam relação alométrica de peso/comprimento positiva. A reprodução ocorreu principalmente entre os meses de janeiro e fevereiro. Fêmeas atingiram o tamanho de primeira maturação (L50) com 37,80 mm e machos com 45,80 mm. A fecundidade absoluta média foi 177,43 (dp±127,06) ovócitos e a fecundidade relativa foi de 3,12 (dp±2,23) ovócitos/mg. A fecundidade foi positivamente correlacionada com o comprimento padrão (Spearman r= 0,43; p=0,013) e a desova parcelada foi a estratégia de desova utilizada por H. inexspectatum.

Reproductive ecology of Otocinclus vittatus (Regan, 1904) in the Pantanal floodplain, upper Paraguay River basin / Ecologia reprodutiva de Otocinclus vittatus (Regan, 1904) na planície de inundação do Pantanal, bacia do alto rio Paraguai

Abstract We studied the reproductive biology of Otocinclus vittatus in the southern Pantanal, Brazil. A total of 1066 fishes were analyzed (490 males, 488 females and 88 individuals of undetermined sex), sampled with a rectangular sieve and a seine net from February/2009 to January/2011. Variations in the sex ratio, seasonality in reproduction, fecundity, and size at first maturity were estimated. No variations were detected in the total sex ratio for the study period as a whole; although ratio has varied over time. The gonadosomatic index varied according to the river level, but not according to water temperature and rainfall. The mean fecundity was estimated at 84.1 oocytes, with a positive correlation with standard length. The size at first maturity (L50) estimated was 18.7 mm for females and 20.1 mm for males.

Resumo Estudamos a biologia reprodutiva de Otocinclus vittatus no Pantanal Sul, Brasil. Um total de 1066 peixes foram analisados (490 machos, 488 fêmeas e 88 de sexo indeterminado), amostrados com tela de isca e rede de arrasto entre Fevereiro/2009 e Janeiro/2011. Foram estimadas as variações na proporção sexual, a sazonalidade na reprodução e o tamanho da primeira maturação. Não foi detectada variação na proporção sexual total para o período de estudo como um todo; embora a proporção tenha variado ao longo do tempo. O índice ganadossomático variou de acordo com o nível do rio, mas não de acordo com a temperatura da água e a pluviosidade. A média de fecundidade foi estimada em 84.1 ovócitos, com uma correlação positiva com o comprimento padrão. O tamanho de primeira maturação (L50) foi estimado em 18.7 mm para fêmeas e 20.1 mm para machos.

Life-history traits of Farlowella hahni (Siluriformes, Loricariidae) in streams of the Ivinhema River Basin, Upper Paraná Basin / Traços de história de vida de Farlowella hahni (Siluriformes, Loricariidae) em riachos da Bacia do rio Ivinhema, Bacia do alto Paraná

Abstract Brazilian laws allow the catch of some species as ornamental fish; however, in the absence of biological information, such catch can threaten species conservation. Therefore, this study aimed to offer population and reproductive information about Farlowella hahni in streams of the Ivinhema River Basin, Upper Paraná Basin. To accomplish this, a total of 165 F. hahni individuals were analyzed, including 109 females and 48 males, resulting in an important sex ratio difference from 1:1 (χ 2=19.97; p<0.001), indicating a predominance of females throughout the year. Females reach higher standard length than males. Males presented isometric Length-Weight Relationships, while females have positive allometric growth. Gonadosomatic index presented higher values from October through December. The mean fecundity was 100.3±36.4 of vitellogenic oocytes and was positively correlated with standard length (r=0.51; p=0.01). The data presented herein are the first for this species and suggest a need to carefully manage the F. hahni population, considering its low abundance and fecundity.

Resumo As leis brasileiras permitem a captura de algumas espécies de peixes como ornamentais, no entanto, a ausência de informações biológicas pode tornar esta captura uma ameaça para a conservação destas espécies. Este estudo teve como objetivo oferecer informações populacionais e reprodutivas sobre Farlowella hahni em riachos da Bacia do rio Ivinhema, bacia do Alto Paraná. Um total de 165 indivíduos de F. hahni foi analisado, sendo 109 fêmeas e 48 machos. A proporção de sexo foi diferente de 1:1 (χ2=19,97; p<0,001), com predominância de fêmeas ao longo do ano. As fêmeas atingiram maior comprimento padrão do que os machos. Os machos apresentaram crescimento isométrico e as fêmeas crescimento alométrico positivo. O índice gonadossomático apresentou maiores valores de Outubro a Dezembro. A fecundidade média foi de 100,3±36,4 de ovócitos vitelogênicos e foi correlacionada positivamente com o comprimento padrão (r=0,51; p=0,01). Os dados apresentados são os primeiros para essa espécie e sugerem a necessidade de cuidados no manejo da população de F. hahni considerando baixa abundância e fecundidade.

Reproductive biology of Hyphessobrycon eques (Characiformes: Characidae) in Southern Pantanal, Brazil / Biologia Reprodutiva de Hyphessobrycon eques (Characiformes: Characidae) no Pantanal Sul, Brasil

Abstract Population and reproductive aspects allow the knowledge and understanding of population dynamics and the influence of environmental factors, in addition to ensure the success of a species continuity. Thus, the aim of this study was to analyze population and reproductive traits of the species Hyphessobrycon eques in southern Pantanal, Brazil. Monthly samplings were conducted from February/2009 to January/2011, with 617 individuals analyzed, being 365 females and 262 males. A similar form of distribution in length and weight between the sexes was observed. There was no significant variation in sex ratio over time, with higher proportion of females during the entire sampled period. Both sexes presented a angular coefficient of Weight/Length (b) relationship greater than 3, with speed of increase in weight greater than in length. For females, a long reproductive period was observed, with greater reproductive intensity from January through June. No significant correlation was observed between the Gonadosomatic Index (GSI) and the average temperature, rainfall and river level, despite the fact that reproductive activity occurs in autumn/winter, when there are favorable conditions due to flooding. The size at first maturation (L50) was 20.2 mm, with confidence interval varying from 19.7 through 20.7 mm. The average fecundity was 191.9 oocytes/females and was significantly related to the standard length and total weight (g), demonstrating a relation with energy accumulation to invest in reproduction. The long reproductive period, intensified by partial spawning, higher proportion of females and low L50, show that the species has strategies necessary for survival and rapid population growth, common in small species characterized as r-strategists.

Resumo Os aspectos populacionais e reprodutivos permitem o conhecimento e a compreensão da dinâmica populacional e da influência de fatores ambientais, assegurando o sucesso da continuidade de uma espécie. Desta forma, o presente trabalho teve como objetivo analisar os traços populacionais e reprodutivos da espécie Hyphessobrycon eques no Sul do Pantanal, Brasil. Foram realizadas amostragens mensais de Fevereiro/2009 a Janeiro/2011, com um total de 617 indivíduos analisados, sendo 365 fêmeas e 262 machos. Foi observada que a distribuição foi similar em comprimento e peso entre os sexos. Não ocorreu variação significativa na proporção sexual ao longo do tempo, com maior proporção de fêmeas durante todo período amostrado. Ambos os sexos apresentaram um coeficiente angular da relação Peso/Comprimento (b) maior que 3, com velocidade do incremento em peso maior do que em comprimento. Para as fêmeas, foi observado um período reprodutivo longo, com maior intensidade reprodutiva de Janeiro e Junho. Não foi observada correlação significativa entre o Índice Gonadossomático (IGS) e a temperatura média, pluviosidade e nível do rio, apesar de ocorrer atividade reprodutiva no outono/inverno, período que há condições favoráveis decorrentes da inundação. O tamanho de primeira maturação (L50) foi de 20,2 mm, com intervalo de confiança variando entre 19,7 e 20,7 mm. A fecundidade média foi de 191,9 ovócitos/fêmea e esteve relacionada significativamente ao comprimento padrão e peso total (g), demonstrando uma relação com acúmulo de energia para investir na reprodução. O período reprodutivo longo, intensificado pela desova parcelada, maior proporção de fêmeas e baixo L50, mostram que a espécie possui estratégias necessárias para sobrevivência e rápido crescimento da população, comum em espécies de pequeno porte caracterizadas como r-estrategistas.

Reproductive ecology of Otocinclus vittatus (Regan, 1904) in the Pantanal floodplain, upper Paraguay River basin.

We studied the reproductive biology of Otocinclus vittatus in the southern Pantanal, Brazil. A total of 1066 fishes were analyzed (490 males, 488 females and 88 individuals of undetermined sex), sampled with a rectangular sieve and a seine net from February/2009 to January/2011. Variations in the sex ratio, seasonality in reproduction, fecundity, and size at first maturity were estimated. No variations were detected in the total sex ratio for the study period as a whole; although ratio has varied over time. The gonadosomatic index varied according to the river level, but not according to water temperature and rainfall. The mean fecundity was estimated at 84.1 oocytes, with a positive correlation with standard length. The size at first maturity (L50) estimated was 18.7 mm for females and 20.1 mm for males.

Life-history traits of Farlowella hahni (Siluriformes, Loricariidae) in streams of the Ivinhema River Basin, Upper Paraná Basin.

Brazilian laws allow the catch of some species as ornamental fish; however, in the absence of biological information, such catch can threaten species conservation. Therefore, this study aimed to offer population and reproductive information about Farlowella hahni in streams of the Ivinhema River Basin, Upper Paraná Basin. To accomplish this, a total of 165 F. hahni individuals were analyzed, including 109 females and 48 males, resulting in an important sex ratio difference from 1:1 (χ 2=19.97; p<0.001), indicating a predominance of females throughout the year. Females reach higher standard length than males. Males presented isometric Length-Weight Relationships, while females have positive allometric growth. Gonadosomatic index presented higher values from October through December. The mean fecundity was 100.3±36.4 of vitellogenic oocytes and was positively correlated with standard length (r=0.51; p=0.01). The data presented herein are the first for this species and suggest a need to carefully manage the F. hahni population, considering its low abundance and fecundity.

Reproductive biology of Hyphessobrycon eques (Characiformes: Characidae) in Southern Pantanal, Brazil.

Population and reproductive aspects allow the knowledge and understanding of population dynamics and the influence of environmental factors, in addition to ensure the success of a species continuity. Thus, the aim of this study was to analyze population and reproductive traits of the species Hyphessobrycon eques in southern Pantanal, Brazil. Monthly samplings were conducted from February/2009 to January/2011, with 617 individuals analyzed, being 365 females and 262 males. A similar form of distribution in length and weight between the sexes was observed. There was no significant variation in sex ratio over time, with higher proportion of females during the entire sampled period. Both sexes presented a angular coefficient of Weight/Length (b) relationship greater than 3, with speed of increase in weight greater than in length. For females, a long reproductive period was observed, with greater reproductive intensity from January through June. No significant correlation was observed between the Gonadosomatic Index (GSI) and the average temperature, rainfall and river level, despite the fact that reproductive activity occurs in autumn/winter, when there are favorable conditions due to flooding. The size at first maturation (L50) was 20.2 mm, with confidence interval varying from 19.7 through 20.7 mm. The average fecundity was 191.9 oocytes/females and was significantly related to the standard length and total weight (g), demonstrating a relation with energy accumulation to invest in reproduction. The long reproductive period, intensified by partial spawning, higher proportion of females and low L50, show that the species has strategies necessary for survival and rapid population growth, common in small species characterized as r-strategists.

Reproductive ecology of Otocinclus vittatus (Regan, 1904) in the Pantanal floodplain, upper Paraguay River basin

Abstract We studied the reproductive biology of Otocinclus vittatus in the southern Pantanal, Brazil. A total of 1066 fishes were analyzed (490 males, 488 females and 88 individuals of undetermined sex), sampled with a rectangular sieve and a seine net from February/2009 to January/2011. Variations in the sex ratio, seasonality in reproduction, fecundity, and size at first maturity were estimated. No variations were detected in the total sex ratio for the study period as a whole; although ratio has varied over time. The gonadosomatic index varied according to the river level, but not according to water temperature and rainfall. The mean fecundity was estimated at 84.1 oocytes, with a positive correlation with standard length. The size at first maturity (L50) estimated was 18.7 mm for females and 20.1 mm for males.

Resumo Estudamos a biologia reprodutiva de Otocinclus vittatus no Pantanal Sul, Brasil. Um total de 1066 peixes foram analisados (490 machos, 488 fêmeas e 88 de sexo indeterminado), amostrados com tela de isca e rede de arrasto entre Fevereiro/2009 e Janeiro/2011. Foram estimadas as variações na proporção sexual, a sazonalidade na reprodução e o tamanho da primeira maturação. Não foi detectada variação na proporção sexual total para o período de estudo como um todo; embora a proporção tenha variado ao longo do tempo. O índice ganadossomático variou de acordo com o nível do rio, mas não de acordo com a temperatura da água e a pluviosidade. A média de fecundidade foi estimada em 84.1 ovócitos, com uma correlação positiva com o comprimento padrão. O tamanho de primeira maturação (L50) foi estimado em 18.7 mm para fêmeas e 20.1 mm para machos.

Reproduction of Hypoptopoma inexspectatum (Holmberg, 1893) (Siluriformes, Loricariidae) in the Southern Pantanal Floodplain, Upper Paraguay River Basin, Brazil

Abstract This work aimed to describe the reproductive biology of Hypoptopoma inexspectatum in southern Pantanal. A total of 538 individuals were sampled and analyzed from February 2009 through January 2011 in southern Pantanal. We did not observe differences in sex-ratio, and both sexes presented positive allometric length/weight relationship (LWR). Reproduction occurs mainly from January to February. Females reached first maturation (L50) with 37.80 mm and males with 45.80 mm. Absolute fecundity is estimated in mean=177.43 (sd±127.06) oocytes and relative fecundity in 3.12 (sd±2.23) oocytes/mg. Fecundity is positively correlated with standard length (Spearman r= 0.43; p=0.013), and total spawning is a used spawning strategy for H. inexspectatum.

Resumo Este trabalho teve como objetivo descrever a biologia reprodutiva de Hypoptopoma inexspectatum na região do Pantanal Sul. Foram amostrados e analisados entre fevereiro de 2009 a janeiro de 2011 um total de 538 indivíduos. Não foi observada diferença na proporção sexual e ambos os sexos apresentam relação alométrica de peso/comprimento positiva. A reprodução ocorreu principalmente entre os meses de janeiro e fevereiro. Fêmeas atingiram o tamanho de primeira maturação (L50) com 37,80 mm e machos com 45,80 mm. A fecundidade absoluta média foi 177,43 (dp±127,06) ovócitos e a fecundidade relativa foi de 3,12 (dp±2,23) ovócitos/mg. A fecundidade foi positivamente correlacionada com o comprimento padrão (Spearman r= 0,43; p=0,013) e a desova parcelada foi a estratégia de desova utilizada por H. inexspectatum.

Can the chlorophyll-a fluorescence be useful in identifying acclimated young plants from two populations of Cecropia pachystachya Trec. (Urticaceae), under elevated CO2 concentrations?

The physiological behavior of PSII measured by chlorophyll a fluorescence explains stress responses; wonders if it can differentiate plants from different populations. For this purpose, acclimated young plants of two C. pachystachya populations were cultivated from seeds. Chlorophyll-a fluorescence was measured after fertilization and [CO(2)](e). In the first 48 h after fertilization there was a reduction in the maximum quantum yield of PSII, while the means obtained under [CO(2)](e) were significantly higher than in other treatments (0.8 and 0.81). The variable PI best expressed the different conditions tested. Compared to their respective controls, the reduction of DIo/CS was 35.89 % in population (P) and 41.89 % in population (I), while the polyphasic fluorescence kinetics differed between treatments, but not necessarily between populations, except for post-fertilization at I-P steps. The analysis of kinetics between Fo and Fj (Wt) showed no K band during the O-J phase. The interferences found in PSII reinforces the idea of reversible damage to PSII. This effect is directly related to the reduced electron transport rate and increased non-photochemical dissipation and may be similar to those observed under field conditions after planting; adjustment time depends, among other factors, on the genetic potential of the species.

Fourier transform infrared photoacoustic spectroscopy as a potential tool in assessing the role of diet in cuticular chemical composition of Ectatomma brunneum.

The cuticular chemical composition plays a significant role in the recognition of nest mates in social insects, thus functioning as a chemical signature of the colony. The structure of cuticular chemicals is subject to interference from genetic and exogenous factors, including diet. In this study, various colonies of the Ectatomma brunneum ant were removed from their natural environment and housed in a laboratory to monitor the response of the cuticular chemical composition to dietary changes. Analyses were performed using gas chromatography and Fourier transform infrared photoacoustic spectroscopy, which has not been previously used for this type of analysis. The results indicate that this method is useful for analyzing biological and natural systems. We observed changes in the chemical signature with food traces in the first 30 days under feed control. Therefore, genetic information may not be the only criterion that can be used to describe the chemical signature of a species; environmental variations also influence recognition signals. Furthermore, these results reinforce the reliability of the Fourier transform infrared photoacoustic spectroscopy method.

Distinct linear hydrocarbon profiles and chemical strategy of facultative parasitism among Mischocyttarus wasps.

Insects use pheromones as a means of chemical communication. Pheromones act on individual receptors and produce specific behavioral or physiological responses that are fundamental to intra- and interspecific recognition. The objective of this study was to evaluate the interspecific differences among the linear hydrocarbon profiles of the cuticles of 3 wasp species of the genus Mischocyttarus. The chemical strategy that permits an interaction among 2 of these species was also examined about their hydrocarbon profiles. The cuticular hydrocarbons present on the abdomen of each individual were extracted with hexane in an ultrasonic bath and analyzed using gas chromatography with a flame ionization detector. The results suggested that the wasp species have distinct chemical signatures as the linear hydrocarbons of their cuticles. However, these signatures are more alike in those with similar morphological and behavioral aspects. These similarities facilitate an interaction of facultative parasitism observed among these species, in which the invaders acquire parts of the chemical signature of the host colony, possibly as a chemical strategy to increase the likelihood that an invader will be accepted by the females of a host colony. Both invader and host have their own chemical signature changed by the first contact between the species.

Age-related changes in the surface pheromones of the wasp Mischocyttarus consimilis (Hymenoptera: Vespidae).

One of the most important attributes that allowed the evolution and maintenance of sociality in insects is their ability to distinguish members of their own colonies. The capacity for individual recognition in social insects is mediated by chemical signals that are acquired soon after the adult emerges, and vary according to the tasks performed by individuals in their colonies. We determined the time when adults of the wasp Mischocyttarus consimilis acquire the chemical signature of their colonies, as well as the variation in the cuticular hydrocarbon profiles of the exoskeleton of individuals, according to their functions in the colony. The method used was Fourier transform infrared photoacoustic spectroscopy directly on the gaster of each individual. Young wasps take three to four days to acquire the colony's chemical signature, with a small change on the fifth day, when the cuticular hydrocarbon profile of the workers is more similar to that of the queens than that of the males, probably because they are of the same sex, but primarily because of the similarity of tasks executed by these two groups of females in the colonies.