Monogeneans of Colossoma macropomum (Cuvier, 1818) (Characiformes: Serrasalmidae) farmed in the state of Acre, Amazon (Brazil).

Parasitism of Colossoma macropomum is of particular concern because it is the most commonly farmed native fish species in Brazil. Nevertheless, the parasitic fauna of this species in the state of Acre has been little studied. For this reason, an evaluation was made of the parasitic fauna of farmed C. macropomum in the municipality of Rio Branco in southwestern Amazon. Four monogenean species were found in the 122 fish examined: Anacanthorus spathulatus, Linguadactyloides brinkmanni, Notozothecium janauachensis and Mymarothecium boegeri. The most prevalent species was A. spathulatus (50%), followed by N. janauachensis (44.3%), M. boegeri (20.5%) and L. brinkmanni (9.0%). These results are the first data on the ecological indices of monogeneans in tambaqui in the state of Acre and will be useful for future comparisons of the influence of environmental factors on the parasite-host relationship.

Integrative taxonomy of Goezia spinulosa (Nematoda: Raphidascarididae) from arapaimas in the northwestern Brazil.

Arapaima gigas, a fish with a high market value, has been farmed in different localities within Brazil. Among its parasites, adults of Goezia spinulosa are reported to cause ulcers in the stomach and to result in the death of farmed fingerlings. Due to the veterinary importance of this nematode in cultured arapaimas, an integrative taxonomic study is proposed, combining morphological, ultrastructural and genetic profiles of this parasite. The fish were obtained from semi-intensive fish farming in Acre State, Brazil. The fish measured 7-42cm in total length and the intensity of infection was 1-60 parasites per fish. The site of infection was mainly the stomach. Morphological and ultrastructural analyses of G. spinulosa showed the importance of its spiny body in firmly attaching the worm to the gastric mucosa, resulting in lesions, ulcers and deep gastric perforations of the stomach wall. New sequences for partial 18S rDNA, ITS1, 5.8S and ITS2 rDNA, partial 28S rDNA, cox1 mtDNA and for cox2 mtDNA are presented. Phylogenetic reconstructions based on the partial 18S and 28S rDNA shows species of Goezia occur in a clade well separated from other genera in both analyses. Both the partial 18S and 28S rDNA genes represented good genetic markers for distinguishing genera of the Raphidascarididae, with exception of Hysterothylacium. This integrated taxonomic study produced a robust profile for G. spinulosa that will aid the diagnosis of both adults and larval stages from arapaimas and possible intermediate hosts.

Effects of flood regime on the diet of Triportheus curtus (Garman, 1890) in an Amazonian floodplain lake

We analyzed the diet of Triportheus curtus in Lake Amapá on the Acre River (AC - Brazil), during three distinct phases of the hydrological cycle (pre-flooding, flooding, and post-flooding stages). The flooding occurred between January and June of 2009. Samples were collected monthly from October 2008 through September 2009. After collection (at 19:00, 01:00, 07:00, and 13:00 hs) and taxonomic identification, fish were eviscerated and their stomachs preserved in a 4 percent formalin solution for later analysis. The diet was evaluated by the Index of Relative Importance (IRI), and temporal variations (pre-flooding, flooding, and post-flooding) in the diet were summarized by an ordination technique (DCA). The diet of T. curtus was comprised of several orders of insects and microcrustaceans. In the pre-flooding stage, more than 62 percent of the diet consisted of Ostracoda. In the flooding phase, T. curtus fed mainly on Chaoboridae larvae (Diptera) (44.3 percent) and terrestrial insects (fragments) (33.7 percent). In the post-flooding phase, Chaoboridae comprised 80 percent of the diet. These results indicate that the utilization of food resources by T. curtus was variable, changing with alterations in the availability of resources, as influenced by the hydrological cycle. The population of T. curtus proved to be opportunistic, changing its diet in the course of the hydrological cycle.

Neste estudo avaliamos a dieta de Triportheus curtus, no lago Amapá, rio Acre (AC - Brasil), em três períodos distintos do ciclo hidrológico (pré-pulso, pulso e pós-pulso). As coletas foram realizadas mensalmente de outubro de 2008 a setembro de 2009, e o pulso de cheia ocorreu entre janeiro e junho de 2009. Após as despescas (19:00, 01:00, 07:00 e 13:00 hs) e identificação taxonômica, os indivíduos foram eviscerados e os estômagos preservados em formalina 4 por cento para posterior análise. A dieta foi avaliada através do Índice de Importância Relativa (IRI), e as variações temporais (pré-pulso, pulso e pós-pulso) na dieta foram sumarizadas através de uma análise de ordenação (DCA). A dieta de T. curtus foi composta de insetos de diferentes ordens e microcrustáceos. No pré-pulso, aproximadamente 62 por cento da dieta foi composta por Ostracoda. No pulso, T. curtus consumiu principalmente larvas de Chaoboridae (Diptera) (44,3 por cento) e insetos terrestres (fragmentos) (33,7 por cento). No pós-pulso, larvas de Chaoboridae representaram 80 por cento da dieta. Estes resultados indicam que a dieta de T. curtus varia temporalmente, e que a espécie pode ser considerada oportunista, alterando sua dieta de acordo com a abundância dos recursos nas diferentes fases do ciclo hidrológico.