Index). Spearman correlation analysis, a glm and CCA were performed between biotic and abiotic variables, and we used the CPUE as a measure of fish abundance. Results: Eleven taxa of fish were recorded, four of which were predated by adult "trahira". Insects and other items were also common in the stomachs of juveniles. According to statistical analysis, it was observed that the highest consumption of cichlids was correlated with its increase in CPUE in the environment, while no relationship was observed for A. bimaculatus, C. bimaculatum and S. notonota abundances. The environmental factors as nutrients, transparency and water volumn were related to selection of species by trahira. Conclusions: Intrinsic characteristics of preys as swimming speed, food habit and the food preference of the predator possibly be the main factors to selection of species. Other mechanisms as heterogeneity of habitat and environmental factors can also influence the consumption of prey by trahira.

To determine the fish species present in Taperoá II Reservoir, and their relevance to the local economy, this research aimed to evaluate the composition, abundance, degree of dominance and constancy of species, along with diversity, richness, evenness and similarity indices in a tropical semi-arid fish assemblage, during one year. Six 24 hour-long samplings were carried out between October 2005 and October 2006 using cast, seine and gillnets. The 889 collected individuals belonged to 11 species from 9 families. Temporal variation was observed in the capture frequency of different species, and a significant negative correlation between precipitation and number of individuals was also observed. Among the recorded families, Characidae showed a higher frequency of occurrence (38.4%), mostly due to Astyanax bimaculatus (Linnaeus, 1758) and A. fasciatus (Cuvier, 1819). Eight species were categorised as constant, two as accessory and one as accidental. Diversity index values were intermediate with low fluctuation throughout the study period, and no correlation with precipitation or water volume. However, the greatest diversity value was recorded in March 2006, when the peak of the precipitation was recorded. Evenness values showed a similar trend to the diversity index.Keywords: reservoir, ecology, community, temporal variation. Diversidade da ictiofauna do açude Taperoá II, semiárido paraibano, Brasil ResumoPara determinar as espécies de peixe presentes no Açude Taperoá II e sua relevância para a economia local, objetivou-se determinar a composição, a abundância, a dominância e a constância de espécies da ictiofauna, bem como os índices de diversidade (H'), riqueza, equitabilidade e similaridade de espécies ao longo de um ano. Foram realizadas seis coletas ao longo de 24 horas, de outubro de 2005 a outubro de 2006, utilizando-se tarrafas, redes de espera e arrasto. Foram coletados 889 indivíduos, identificados em 11 táxons específicos, distribuídos em nove famílias. A abundância das diferentes espécies variou temporalmente, com correlação negativa significativa entre a precipitação e o número de indivíduos. Dentre as famílias identificadas, Characidae apresentou a maior frequência de ocorrência (38,5%), representada pelas espécies Astyanax bimaculatus (Linnaeus, 1758) e A. fasciatus (Cuvier, 1819). Oito espécies foram consideradas constantes, duas acessórias e uma acidental. O índice de diversidade apresentou valores entre 2,11 e 2,80, e não apresentou correlação com a precipitação e o volume do açude. Entretanto, o índice de diversidade mais elevado foi registrado no mês de março de 2006, pico do período chuvoso. Os valores da equitabilidade comportaram-se de forma semelhante aos do índice de diversidade.Palavras-chave: reservatório, ecologia, comunidade, variação temporal.

ResumoAspectos da estrutura populacional e alimentar de Leporinus piau Fowler, 1941 (Actinopterygii, Characiformes, Anostomidae) do Açude Taperoá II, na região do semi-árido da Paraíba, Brasil. Objetivouse determinar a estrutura populacional, estabelecer a relação peso-comprimento, a proporção sexual, a relação entre a atividade alimentar e o período reprodutivo, e identificar a dieta e o regime alimentar de Leporinus piau. Foram realizadas seis coletas, nos meses de outubro e dezembro de 2005; março, junho, agosto e outubro de 2006, utilizando-se tarrafas, redes de espera e arrasto. Alguns exemplares foram enviados à Coleção Ictiológica da UFPB. Foram coletados 89 indivíduos de comprimentos que variaram de 6,2cm a 22,0cm. O crescimento foi do tipo alométrico negativo. Houve um predomínio significativo de machos. A dieta alimentar de L. piau se mostrou variada, sugerindo onivoria e oportunismo.Unitermos: alimentação, Anostomidae, dinâmica populacional, ictiofauna, semi-árido AbstractThe aim of this research was to determine the population structure, weight-length relationship and sexual ratio of Leporinus piau. It also attempted to evaluate the relationship between the alimentary activity and the reproductive period, and to identify the diet and alimentary regimen. Six collections were made in the months of October and December of 2005 and March, June, August and October of 2006, using casting, seining and gill nets. Some specimens were sent to the UFPB Ichthyological Collection. The 89 collected individuals presented lengths varying from 6.2cm to 22cm. The growth of the species was of the negative allometric type. There was a significant predominance of males. The alimentary diet of L. piau was apparently variable, suggesting omnivorousness.

AIM: The present study investigated population structure, weight-length relationships, sex ratio and associations between feeding activity and reproductive period, diet and alimentary regime of Steindachnerina notonota at Taperoá II dam, semi-arid region of Paraíba State. METHODS: The region has the lowest pluviometric rates of Brazil. Fishes were collected during six sampling periods (October and December/2005, and March, June, August and October of 2006) encompassing two dry periods, and one rainy period. Cast, seine and gill nets were used to collect the individuals. RESULTS: Throughout the study period 120 individuals were collected, with total length ranging between 2.2 and 10.7 cm and weight between 0.31 and 43.1 g. A recruitment period, identified due to a higher abundance of small individuals in the population, was observed in the beginning of the rainy period of 2006, lasting until the beginning of the dry season. S. notonota showed a negative allometric growth type, i.e., individuals 'elongate' during their development. A significantly higher proportion of females were observed throughout the study period. The relationship between feeding and reproductive activities were not significant, given that individuals showed high feeding rates regardless of the intensity of their reproductive activities. Although the diet of S. notonota comprised several items such as plant debris, eggs, organic matter, phytoplankton, zooplankton, Nematoda, Ostracada, Conchostraca, among others, the most important feeding item was detritus, suggesting a predominant detritivirous feeding habit. CONCLUSIONS: Biological aspects of S. notonota observed in the present study suggest that this species has potential to attain great population sizes, as consequence of both diet and feeding dynamics, as well as its reproductive characteristics and growth type.

Role of the rain and macrophytes on temporal and spatial pattern of ichthyoplankton in the Caatinga Biome, Brazil Papel da chuva e das macrófitas no padrão temporal e espacial do ictioplâncton no Bioma Caatinga, Brasil