ABSTRACT
In this study, the composition of the diet and the feeding activity of Electrophorus varii were evaluated. The influence of ontogeny and seasonality in these feeding parameters was also examined. Fish were collected in the Curiaú River Basin, Amazon, Brazil, from March 2005 to February 2006, during the rainy (January-June) and dry (July-December) seasons. Diet composition was characterized based on the analysis of stomach contents and feeding dynamics was assessed based on the Stomach Fullness Index (IR) calculated using stomach weight. Stomach content and RI data were grouped into four-cm size classes (40-80, 80-120, 120-160, and 160-200) and two seasonal periods (rainy and dry). The influence of ontogeny and seasonality in the diet was investigated through PERMANOVA, and in the food dynamics through ANOVA. The analysis of stomach contents revealed that fish were the most consumed preys by electric eels, especially Callichthyidae and Cichlidae. Diet composition and RI values of electric eels were not influenced by ontogeny and seasonality. Electric eels are fish predators, regardless of size class and seasonal period.(AU)
Neste estudo foram avaliadas a composição da dieta e a atividade alimentar de Electrophorus varii. A influência da ontogenia e da sazonalidade nestes aspectos da alimentação dos poraquês também foi examinada. Os peixes foram coletados na Bacia do rio Curiaú, Amazônia, Brasil, no período de março de 2005 a fevereiro de 2006, abrangendo os períodos chuvoso (janeiro-junho) e o seco (julho-dezembro). A dieta foi avaliada por meio da análise dos conteúdos estomacais e a dinâmica alimentar por meio do Índice de Repleção Estomacal (RI) baseado nos dados de peso do estômago. Os dados do conteúdo estomacal e do RI foram agrupados em quatro classes de tamanho em cm (40-80, 80-120, 120-160 e 160-200) e dois períodos sazonais (chuvoso e seco). A influência da ontogenia e da sazonalidade na dieta foi investigada por meio da PERMANOVA, e na dinâmica alimentar por meio da ANOVA. A análise do conteúdo estomacal mostrou que os peixes foram as presas mais consumidas pelos poraquês, especialmente Callichthyidae e Cichlidae. A composição da dieta e os valores de RI dos poraquês não foram influenciadas pela ontogenia e pela sazonalidade. Os poraquês são predadores piscívoros, independente da classe de tamanho e do período sazonal.(AU)
Subject(s)
Animals , Analysis of Variance , Gymnotiformes , Ecology , Eels , FishesABSTRACT
This study compared the parasites fauna of Hyphessobrycontakasei and H. amapaensisfrom hydrographic basins in Amapá state, Brazil. Of the 42 H. takasei examined, 95.2% were parasitized by one or more species such as Dactylogyridae gen. sp., encysted metacercariae of digenean, adults and larvae of Procamallanus (Spirocamallanus) inopinatus and larvae of Camallanus sp. A total of 224 parasites were collected from H.takasei, and there was a dominance of nematode species and dispersion pattern aggregated of parasites. The species richness of parasites varied of 0 to 3 species, Brillouin index of 0-0.97 and evenness of 0-0.70. Of the 32 specimens of H. amapaensis examined, 28.1% were parasitized by Camallanus sp. larvae, which presented random dispersion pattern. For H. takasei, no correlation of host length with Brillouin diversity and species richness of parasites was found. The presence of these nematode species and metacercariae of digenean indicates that these fish may act as intermediate hosts. This is the first study to gather information about the parasite fauna of these endemic fish from the eastern Amazon, providing records that contribute new reports on occurrence of parasite species in new localities. This study on parasites of H. takasei and H. amapaensis may help prevent the introduction of parasites in other regions of the country, as well as in other countries due to aquarium fish.Since the ornamental fish exportation from the Brazil is largely dominated by wild Amazonian species, biosecurity export conditions should be require all exported fish to be inspected and certified to show no clinical signs of parasite and diseases. Lastly, this knowledge on the parasitic epidemiology may help improve the health and quality of these fish being exported from the Amazon region, reducing losses on all stages of this production chain.