Reproductive biology of the mullet Mugil liza (Teleostei: Mugilidae) in a tropical Brazilian bay

The reproductive biology of Mugil liza Valenciennes, 1836 is described as a contribution to an elaborate management programm. A total of 243 specimens (89 males and 154 females) were collected in the Sepetiba Bay in south-eastern Brazil from July/2006 to June/2007. The gonadosomatic index (I G) and the sequential development of the ovaries observed through histological studies suggested that the spawning season ranged from May to August. The population reached total sexual maturity (L T100) at 550 and 570 mm total length (L T) for males and females, respectively. Females attained a larger size than males, and the sex ratio was female-biased for fish larger than 500 mm L T. The hepatosomatic index (I H) was significantly related to the I G, indicating that vitellogenesis mobilizes hepatic energy during reproduction. Mean fecundity was 3,080,000 oocytes. The presence of only two phases of oocyte development in ripe ovaries - a reserve stock and a clutch of post-vitellogenic oocytes - indicated that ovarian development is group synchronic and this species is characterized as a total spawner. The results suggest that establishing a closed fishing season from May to August and establishing a minimum size for capture of 350 mm L T would enhance stock conservation and production for future harvest seasons.

Reproductive biology of the mullet Mugil liza (Teleostei: Mugilidae) in a tropical Brazilian bay

The reproductive biology of Mugil liza Valenciennes, 1836 is described as a contribution to an elaborate management programm. A total of 243 specimens (89 males and 154 females) were collected in the Sepetiba Bay in south-eastern Brazil from July/2006 to June/2007. The gonadosomatic index (I G) and the sequential development of the ovaries observed through histological studies suggested that the spawning season ranged from May to August. The population reached total sexual maturity (L T100) at 550 and 570 mm total length (L T) for males and females, respectively. Females attained a larger size than males, and the sex ratio was female-biased for fish larger than 500 mm L T. The hepatosomatic index (I H) was significantly related to the I G, indicating that vitellogenesis mobilizes hepatic energy during reproduction. Mean fecundity was 3,080,000 oocytes. The presence of only two phases of oocyte development in ripe ovaries - a reserve stock and a clutch of post-vitellogenic oocytes - indicated that ovarian development is group synchronic and this species is characterized as a total spawner. The results suggest that establishing a closed fishing season from May to August and establishing a minimum size for capture of 350 mm L T would enhance stock conservation and production for future harvest seasons.

Reproductive biology of the mullet Mugil liza (Teleostei: Mugilidae) in a tropical Brazilian bay

The reproductive biology of Mugil liza Valenciennes, 1836 is described as a contribution to an elaborate management programm. A total of 243 specimens (89 males and 154 females) were collected in the Sepetiba Bay in south-eastern Brazil from July/2006 to June/2007. The gonadosomatic index (I G) and the sequential development of the ovaries observed through histological studies suggested that the spawning season ranged from May to August. The population reached total sexual maturity (L T100) at 550 and 570 mm total length (L T) for males and females, respectively. Females attained a larger size than males, and the sex ratio was female-biased for fish larger than 500 mm L T. The hepatosomatic index (I H) was significantly related to the I G, indicating that vitellogenesis mobilizes hepatic energy during reproduction. Mean fecundity was 3,080,000 oocytes. The presence of only two phases of oocyte development in ripe ovaries - a reserve stock and a clutch of post-vitellogenic oocytes - indicated that ovarian development is group synchronic and this species is characterized as a total spawner. The results suggest that establishing a closed fishing season from May to August and establishing a minimum size for capture of 350 mm L T would enhance stock conservation and production for future harvest seasons.

Correction of the weight and length for juveniles Atherinella brasiliensis (Actinopterygii: Atherinopsidae) after fixation in formalin and preservation in ethanol

The present study compared losses of weight and length in specimens of Atherinella brasiliensis (Quoy & Gaimard, 1825) after fixation in formalin 10% during ten days, and posterior preservation in ethanol 70% for 45 days, in two solvents: freshwater and marine water. Additionally, correction factors were proposed to calculate the correction for weight and length from preserved specimens. The specimens were weighted and measured after collection (fresh), and with 10, 20, 27, 34, 41 and 55 days of fixation plus preservation. The largest losses in weight occurred during the first 20 days (10.35 ± 0.31% - freshwater; 11.29 ± 0.44% - marine water), continuing with lesser intensity up to the 27th day in freshwater dilution, and up to the 34th day in marine water dilution. Weight losses stabilized by the 34th day for both freshwater (11.77 ± 0.33%) and marine water (13.62 ± 0.41%). The largest losses in the total length for the two methods were also observed in the first 20 days (7.42 ± 0.27% - freshwater; 9.76 ± 0.26 - marine water), stabilizing after the 27th day in freshwater (8.60 ± 0.26%) and 20th day in marine water (9.76 ± 0.26%). The losses of weight and total length were significantly dependent on fish size, with smaller individuals suffering the most significant losses. Complete regression equations were proposed for the retro-calculation of fresh weight and total length from the preserved specimens for freshwater (Wfresh = 1.0536W P + 0.0416; TLfresh = 0.9588TL P + 5.8437) and marine water (Wfresh = 1.0868W P + 0.0451; TLfresh = 0.8621TL P + 10.425).

Correction of the weight and length for juveniles Atherinella brasiliensis (Actinopterygii: Atherinopsidae) after fixation in formalin and preservation in ethanol

The present study compared losses of weight and length in specimens of Atherinella brasiliensis (Quoy & Gaimard, 1825) after fixation in formalin 10% during ten days, and posterior preservation in ethanol 70% for 45 days, in two solvents: freshwater and marine water. Additionally, correction factors were proposed to calculate the correction for weight and length from preserved specimens. The specimens were weighted and measured after collection (fresh), and with 10, 20, 27, 34, 41 and 55 days of fixation plus preservation. The largest losses in weight occurred during the first 20 days (10.35 ± 0.31% - freshwater; 11.29 ± 0.44% - marine water), continuing with lesser intensity up to the 27th day in freshwater dilution, and up to the 34th day in marine water dilution. Weight losses stabilized by the 34th day for both freshwater (11.77 ± 0.33%) and marine water (13.62 ± 0.41%). The largest losses in the total length for the two methods were also observed in the first 20 days (7.42 ± 0.27% - freshwater; 9.76 ± 0.26 - marine water), stabilizing after the 27th day in freshwater (8.60 ± 0.26%) and 20th day in marine water (9.76 ± 0.26%). The losses of weight and total length were significantly dependent on fish size, with smaller individuals suffering the most significant losses. Complete regression equations were proposed for the retro-calculation of fresh weight and total length from the preserved specimens for freshwater (Wfresh = 1.0536W P + 0.0416; TLfresh = 0.9588TL P + 5.8437) and marine water (Wfresh = 1.0868W P + 0.0451; TLfresh = 0.8621TL P + 10.425).

Correction of the weight and length for juveniles Atherinella brasiliensis (Actinopterygii: Atherinopsidae) after fixation in formalin and preservation in ethanol

The present study compared losses of weight and length in specimens of Atherinella brasiliensis (Quoy & Gaimard, 1825) after fixation in formalin 10% during ten days, and posterior preservation in ethanol 70% for 45 days, in two solvents: freshwater and marine water. Additionally, correction factors were proposed to calculate the correction for weight and length from preserved specimens. The specimens were weighted and measured after collection (fresh), and with 10, 20, 27, 34, 41 and 55 days of fixation plus preservation. The largest losses in weight occurred during the first 20 days (10.35 ± 0.31% - freshwater; 11.29 ± 0.44% - marine water), continuing with lesser intensity up to the 27th day in freshwater dilution, and up to the 34th day in marine water dilution. Weight losses stabilized by the 34th day for both freshwater (11.77 ± 0.33%) and marine water (13.62 ± 0.41%). The largest losses in the total length for the two methods were also observed in the first 20 days (7.42 ± 0.27% - freshwater; 9.76 ± 0.26 - marine water), stabilizing after the 27th day in freshwater (8.60 ± 0.26%) and 20th day in marine water (9.76 ± 0.26%). The losses of weight and total length were significantly dependent on fish size, with smaller individuals suffering the most significant losses. Complete regression equations were proposed for the retro-calculation of fresh weight and total length from the preserved specimens for freshwater (Wfresh = 1.0536W P + 0.0416; TLfresh = 0.9588TL P + 5.8437) and marine water (Wfresh = 1.0868W P + 0.0451; TLfresh = 0.8621TL P + 10.425).

Histologia e caracterização histoquímica do tubo gastrintestinal de Pimelodus maculatus (Pimelodidae, Siluriformes) no reservatório de Funil, Rio de Janeiro, Brasil

Histological structures of the digestive traits of Pimelodus maculatus La Cepède, 1803, in the Funil reservoir (22º30'- 22º35'S; 44º35'- 44º40'W) were described using haematoxilin-eosin (HE), trichome Gomori, periodic acid Schiff (PAS) and alcian blue (AB) pH 2.5 techniques. The main aim of this study was to detect the levels of glycoproteins (GPs) in the mucous tunic based in histochemical techniques and to characterize eventual alteration in the digestive tract of this species in a polluted system. Fifty-four adult individuals collected between April-2003 and July-2004 (TL=19-38 cm) were examined. The mucosa showed longitudinal folds in the buccopharyngeal cavity, with a stratified squamous epithelium. The oesophagus showed epithelium similar to buccopharyngeal cavity, with a predominance of mucous cells, which reacted strongly with the used methods. The stomach showed three regions: cardic, fundic and pyloric. The mucous tunic is continuously revested by a single cylindrical epithelium which showed positive reaction to AB and PAS only at the apical cells surface. The proper tunic has tubular glands that ramify gradatively, being a cellular type named oxyntopeptic, related to chloridric acid and pepsinogenic cells synthesis. The intestine showed vilosities, with the mucous tunic revested by a single cylindrical epithelium with striated planure and caliciform cells. The duodenum submucosa layer was located at the coledocum opening, as a single cylindrical epithelium lacking caliciforms cells, reacting positively with both PAS and AB. The eutrophic environment of Funil reservoir did not seem to influence morphologic patterns of the structures (oesophagus, stomach and intestine) and no modification was observed in the mucous cells activity.

As estruturas teciduais do trato gastrintestinal de Pimelodus maculatus La Cepède, 1803, do reservatório de Funil (22º30'-22º35'S; 44º35'- 44º40'W) foram descritas através das técnicas de hematoxilina-eosina (HE), tricômico Gomori, ácido Periódico de Schiff (PAS) e alcian blue (AB) pH 2,5. Objetivou-se a detecção de glicoproteínas (GPs) na mucosa através de uma análise histoquímica e caracterização de possíveis alterações ao longo do trato digestório destes peixes neste sistema de elevado grau de alteração. Cinqüenta e quatro indivíduos adultos, coletados entre abril de 2003 e julho de 2004 (CT=19-38 cm) foram utilizados. Na cavidade bucofaríngea, a mucosa apresenta-se com pregas longitudinais e o epitélio é do tipo estratificado pavimentoso. O esôfago apresenta o mesmo tipo de epitélio da cavidade bucofaríngea, destacando-se a predominância de células mucosas que tiveram forte reação aos métodos utilizados. O estômago foi diferenciado em região cárdica, fúndica e pilórica. A mucosa é continuamente revestida por um epitélio simples cilíndrico que apresentou reação positiva ao AB e PAS somente na superfície apical das células; a lâmina própria possui glândulas tubulares que se ramificam gradativamente e consistem de um tipo celular denominado oxinticopépticas, relacionadas com a síntese de ácido clorídrico e pepsinogênio. O intestino apresenta vilosidades revestidas por um epitélio simples cilíndrico com planura estriada e células caliciformes. Na camada submucosa do duodeno foi observada a abertura do colédoco, sendo o epitélio do tipo simples cilíndrico sem células caliciformes, positivo tanto ao PAS quanto ao AB. O ambiente eutrófico do reservatório de Funil não parece influenciar os padrões morfológicos das estruturas (esôfago, estômago e intestino) e não foram observadas modificações nas atividades das células mucosas.

Histologia e caracterização histoquímica do tubo gastrintestinal de Pimelodus maculatus (Pimelodidae, Siluriformes) no reservatório de Funil, Rio de Janeiro, Brasil

Histological structures of the digestive traits of Pimelodus maculatus La Cepède, 1803, in the Funil reservoir (22º30'- 22º35'S; 44º35'- 44º40'W) were described using haematoxilin-eosin (HE), trichome Gomori, periodic acid Schiff (PAS) and alcian blue (AB) pH 2.5 techniques. The main aim of this study was to detect the levels of glycoproteins (GPs) in the mucous tunic based in histochemical techniques and to characterize eventual alteration in the digestive tract of this species in a polluted system. Fifty-four adult individuals collected between April-2003 and July-2004 (TL=19-38 cm) were examined. The mucosa showed longitudinal folds in the buccopharyngeal cavity, with a stratified squamous epithelium. The oesophagus showed epithelium similar to buccopharyngeal cavity, with a predominance of mucous cells, which reacted strongly with the used methods. The stomach showed three regions: cardic, fundic and pyloric. The mucous tunic is continuously revested by a single cylindrical epithelium which showed positive reaction to AB and PAS only at the apical cells surface. The proper tunic has tubular glands that ramify gradatively, being a cellular type named oxyntopeptic, related to chloridric acid and pepsinogenic cells synthesis. The intestine showed vilosities, with the mucous tunic revested by a single cylindrical epithelium with striated planure and caliciform cells. The duodenum submucosa layer was located at the coledocum opening, as a single cylindrical epithelium lacking caliciforms cells, reacting positively with both PAS and AB. The eutrophic environment of Funil reservoir did not seem to influence morphologic patterns of the structures (oesophagus, stomach and intestine) and no modification was observed in the mucous cells activity.

As estruturas teciduais do trato gastrintestinal de Pimelodus maculatus La Cepède, 1803, do reservatório de Funil (22º30'-22º35'S; 44º35'- 44º40'W) foram descritas através das técnicas de hematoxilina-eosina (HE), tricômico Gomori, ácido Periódico de Schiff (PAS) e alcian blue (AB) pH 2,5. Objetivou-se a detecção de glicoproteínas (GPs) na mucosa através de uma análise histoquímica e caracterização de possíveis alterações ao longo do trato digestório destes peixes neste sistema de elevado grau de alteração. Cinqüenta e quatro indivíduos adultos, coletados entre abril de 2003 e julho de 2004 (CT=19-38 cm) foram utilizados. Na cavidade bucofaríngea, a mucosa apresenta-se com pregas longitudinais e o epitélio é do tipo estratificado pavimentoso. O esôfago apresenta o mesmo tipo de epitélio da cavidade bucofaríngea, destacando-se a predominância de células mucosas que tiveram forte reação aos métodos utilizados. O estômago foi diferenciado em região cárdica, fúndica e pilórica. A mucosa é continuamente revestida por um epitélio simples cilíndrico que apresentou reação positiva ao AB e PAS somente na superfície apical das células; a lâmina própria possui glândulas tubulares que se ramificam gradativamente e consistem de um tipo celular denominado oxinticopépticas, relacionadas com a síntese de ácido clorídrico e pepsinogênio. O intestino apresenta vilosidades revestidas por um epitélio simples cilíndrico com planura estriada e células caliciformes. Na camada submucosa do duodeno foi observada a abertura do colédoco, sendo o epitélio do tipo simples cilíndrico sem células caliciformes, positivo tanto ao PAS quanto ao AB. O ambiente eutrófico do reservatório de Funil não parece influenciar os padrões morfológicos das estruturas (esôfago, estômago e intestino) e não foram observadas modificações nas atividades das células mucosas.

Diversidade das assembléias de peixes nas quatro unidades geográficas do rio Paraíba do Sul

Diversity patterns of fish assemblages along the four geographic units (upper, middle-upper, middle-lower and lower reaches) of the Paraíba do Sul river were studied aiming to assess spatial (geographic units) and seasonal (wet/dry periods) variations. Twenty-five sites were sampled between December 2002 and March 2003 (summer/wet) and, August to November 2003 (winter/dry). Fish were caught by a standardized effort, using gill nets, cast nets and mesh trays. A total of 81 species were recorded comprised in 9 orders, 29 families and 55 genera. Characiformes showed the highest number of species (28) followed by Siluriformes (23). Perciformes, mainly Tilapia rendalli and Geophagus brasiliensis, and Cyprinodontiformes, mainly Poecilia vivipara and Poecilia reticulata, were the most numerically abundant groups, while Siluriformes, mainly Hypostomus luetkeni, and Perciformes, mainly Geophagus brasiliensis showed the highest biomass. Poecilia vivipara was recorded only in dry period. Spatially, Hoplosternum littorale predominated in the middle-upper reaches, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens in the middle-lower, and Loricariichtys spixii and Prochilodus lineatus, in the lower reach. Number of species and Margalef's richness showed an increase from the upper to the lower river reaches, mainly during the wet period. Species widely distributed along all over the river extent (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) are opportunistic and can use the available resources despite poor environmental conditions, reflecting the state alteration of the river. Differentiation on the physiography throughout the longitudinal extent of the basin does not match shifts in fish assemblages, suggesting that factors associated to habitat alterations could be structuring fish community at local scale.

Padrões na diversidade de peixes ao longo de quatro unidades geográficas (superior, médio-superior, médio-inferior e inferior) no rio Paraíba do Sul foram estudados com a finalidade de avaliar tendências de variações espaciais (unidades geográficas) e temporais (períodos de cheia e seca). Vinte e cinco locais foram amostrados entre Dezembro de 2002 e Março de 2003 (verão/cheia) e, entre Agosto e Novembro de 2003 (inverno/seca). Os peixes foram capturados com um esforço padronizado, utilizando redes de espera, tarrafas e peneiras. Um total de 81 espécies foram registradas compreendendo 9 ordens, 29 famílias e 55 gêneros. Characiformes apresentaram maior número de espécies (28) seguido de Siluriformes (23). Perciformes, principalmente Tilapia rendalli e Geophagus brasiliensis, e Cyprinodontiformes com destaque para Poecilia vivipara e Poecilia reticulata, foram os grupos numericamente mais abundantes, enquanto Siluriformes, principalmente Hypostomus luetkeni, e Perciformes com Geophagus brasiliensis apresentaram maior contribuição em biomassa. Poecilia vivipara foi encontrada apenas no período de seca. Espacialmente, Hoplosternum littorale predominou no trecho médio-superior, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens no trecho médio-inferior, e Loricariichtys spixii e Prochilodus lineatus no trecho inferior. O número de espécies e a riqueza de Margalef apresentaram um aumento do trecho superior para o inferior, principalmente durante o período de cheia. Espécies que apresentaram ampla distribuição ao longo do rio (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) são consideradas oportunistas por se aproveitarem dos recursos disponíveis em ambientes pobres, refletindo o estado de alterações do rio. Diferenciações na fisiografia ao longo da extensão longitudinal da bacia não coincidiram com mudanças nas assembléias de peixes, sugerindo que fatores associados a alterações de hábitats poderiam estar estruturando a comunidade de peixes a nível local.

Diversidade das assembléias de peixes nas quatro unidades geográficas do rio Paraíba do Sul

Diversity patterns of fish assemblages along the four geographic units (upper, middle-upper, middle-lower and lower reaches) of the Paraíba do Sul river were studied aiming to assess spatial (geographic units) and seasonal (wet/dry periods) variations. Twenty-five sites were sampled between December 2002 and March 2003 (summer/wet) and, August to November 2003 (winter/dry). Fish were caught by a standardized effort, using gill nets, cast nets and mesh trays. A total of 81 species were recorded comprised in 9 orders, 29 families and 55 genera. Characiformes showed the highest number of species (28) followed by Siluriformes (23). Perciformes, mainly Tilapia rendalli and Geophagus brasiliensis, and Cyprinodontiformes, mainly Poecilia vivipara and Poecilia reticulata, were the most numerically abundant groups, while Siluriformes, mainly Hypostomus luetkeni, and Perciformes, mainly Geophagus brasiliensis showed the highest biomass. Poecilia vivipara was recorded only in dry period. Spatially, Hoplosternum littorale predominated in the middle-upper reaches, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens in the middle-lower, and Loricariichtys spixii and Prochilodus lineatus, in the lower reach. Number of species and Margalef's richness showed an increase from the upper to the lower river reaches, mainly during the wet period. Species widely distributed along all over the river extent (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) are opportunistic and can use the available resources despite poor environmental conditions, reflecting the state alteration of the river. Differentiation on the physiography throughout the longitudinal extent of the basin does not match shifts in fish assemblages, suggesting that factors associated to habitat alterations could be structuring fish community at local scale.

Padrões na diversidade de peixes ao longo de quatro unidades geográficas (superior, médio-superior, médio-inferior e inferior) no rio Paraíba do Sul foram estudados com a finalidade de avaliar tendências de variações espaciais (unidades geográficas) e temporais (períodos de cheia e seca). Vinte e cinco locais foram amostrados entre Dezembro de 2002 e Março de 2003 (verão/cheia) e, entre Agosto e Novembro de 2003 (inverno/seca). Os peixes foram capturados com um esforço padronizado, utilizando redes de espera, tarrafas e peneiras. Um total de 81 espécies foram registradas compreendendo 9 ordens, 29 famílias e 55 gêneros. Characiformes apresentaram maior número de espécies (28) seguido de Siluriformes (23). Perciformes, principalmente Tilapia rendalli e Geophagus brasiliensis, e Cyprinodontiformes com destaque para Poecilia vivipara e Poecilia reticulata, foram os grupos numericamente mais abundantes, enquanto Siluriformes, principalmente Hypostomus luetkeni, e Perciformes com Geophagus brasiliensis apresentaram maior contribuição em biomassa. Poecilia vivipara foi encontrada apenas no período de seca. Espacialmente, Hoplosternum littorale predominou no trecho médio-superior, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens no trecho médio-inferior, e Loricariichtys spixii e Prochilodus lineatus no trecho inferior. O número de espécies e a riqueza de Margalef apresentaram um aumento do trecho superior para o inferior, principalmente durante o período de cheia. Espécies que apresentaram ampla distribuição ao longo do rio (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) são consideradas oportunistas por se aproveitarem dos recursos disponíveis em ambientes pobres, refletindo o estado de alterações do rio. Diferenciações na fisiografia ao longo da extensão longitudinal da bacia não coincidiram com mudanças nas assembléias de peixes, sugerindo que fatores associados a alterações de hábitats poderiam estar estruturando a comunidade de peixes a nível local.