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

Abstract

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% 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% of the diet consisted of Ostracoda. In the flooding phase, T. curtus fed mainly on Chaoboridae larvae (Diptera) (44.3%) and terrestrial insects (fragments) (33.7%). In the post-flooding phase, Chaoboridae comprised 80% 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% 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% da dieta foi composta por Ostracoda. No pulso, T. curtus consumiu principalmente larvas de Chaoboridae (Diptera) (44,3%) e insetos terrestres (fragmentos) (33,7%). No pós-pulso, larvas de Chaoboridae representaram 80% 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.

Seasonal variation in the use of food resources by small fishes inhabiting the littoral zone in a Neotropical floodplain lake

“…was algivorous. These results are explained by differences in the abundance of resources between dry and rainy periods, and by feeding habits of each species (Esteves and Galetti 1995;Russo and Hahn 2006;Neiff et al 2009;Pereira et al 2011;Carniatto et al 2012). On the other hand, except for H. eques, there were no significant differences in interindividual variation in diet between periods.…”

“…For example, Calanoida copepods have a well-developed ability to escape from predators (Nassal et al 1998), which requires that the predator is active and able to capture them, which may be the case of A. anisitsi and H. eques that exploited this resource when it was theoretically more abundant. On the other hand, consumption of plants does not require very active fish, which may be associated with P. kennedyi that consumed more terrestrial plant in the rainy period, when these resources are carried into the aquatic environment and become available and easily consumed by fish (Novakowski et al 2008;Pereira et al 2011).…”

First study on communities of parasites in Triportheus rotundatus, a Characidae fish from the Amazon River system (Brazil)

“…The species of Triportheus inhabit most of the major river drainages of South America, and constitutes an important element in both commercial and subsistence fisheries in the Amazon basin (MALABARBA, 2004), its reproduction occurs during the rainy season in the Amazon River system (FROESE & PAULY, 2016). Triportheus rotundatus is a benthopelagic fish with an omnivorous diet, fed on fruits, seeds and insects that float on the water surface, besides microcrustaceans (PEREIRA et al, 2011;FROESE & PAULY, 2016;SUÇUARANA et al, 2016). However, studies on the biology of T. rotundatus are reduced, mostly those regarding its parasitic fauna.…”

On the relation amongst limnological factors and fish abundance in reservoirs at semiarid region

“…The species' almost total reliance on shrimp (PS-EQ average: 97.9%), not unlike that of its marine relatives and ancestors (Souza et al, 2008), may explain its successful adaptation to PS and EQ. Thus, while the population of P. squamosissimus is sustained by Macrobrachium sp., the population of T. signatus is favored by the abundance of insects and zooplankton characteristic of eutrophic environments (Eskinazi-Sant'Anna et al, 2007;Hahn & Fugi, 2007;Pereira et al, 2011;Pinto et al, 2011).…”