Trophic guilds of fishes in sandbank habitats of a Neotropical river

Abstract

The objective of this study was to characterize the trophic structure of the community of fishes exploiting riverine sandbank habitats. Collections were carried out during the period of October 1999 to December 2003, on six sand banks in the upper and middle portions of the Tocantins River drainage basin in central Brazil. The availability of food resources was evaluated based on the volume of the items present in the stomachs of all species. A total of 2,127 stomachs of fish belonging to 50 species were analyzed. Nine main trophic guilds grouped the local ichthyofauna according to diet. Aquatic-origin items were the preferred source for 55.5% of the groups analyzed, whereas terrestrial-origin items composed 44.4%. Items of undetermined origin (detritus and sediment), although present in 89% of the guilds, were the predominant food in only one trophic group. Terrestrial insects and fish were the food sources with the largest biomass available in the environment. Sandbank environments are homogeneous, with little shelter and food available; as a rule, the species that occupy these environments are generalists.O presente estudo teve como objetivo caracterizar a estrutura trófica da comunidade de peixes que exploram ambientes de banco de areia. As coletas foram realizadas no período de outubro de 1999 a dezembro de 2003, em seis bancos de areia das porções superior e média da drenagem do rio Tocantins no Brasil central. A disponibilidade dos recursos alimentares foi avaliada a partir do volume dos itens presentes nos estômagos de todas as espécies. Foram analisados 2.127 estômagos de 50 espécies. Nove guildas tróficas principais agrupam a ictiofauna local quanto a sua dieta. Os itens de origem aquática foram a fonte preferencial para 55,5% dos grupos analisados, os terrestres para 44,4% e os itens de origem indeterminada (detrito e sedimento), apesar de presentes em 89% das guildas, foi o alimento predominante somente em um grupo trófico. Os insetos terrestres e os peixes foram os recursos alimentares com maior biomassa disponível no ambiente. Os ambientes de praia são homogêneos, com baixa oferta de abrigo e de alimento, de modo geral, as espécies que ocupam estes ambientes são generalistas.

Trophic structure of a fish community in Bananal stream subbasin in Brasília National Park, Cerrado biome (Brazilian Savanna), DF

“…These characteristics indicate low selectivity and much feeding opportunism (Mazzoni & Rezende, 2003). According to Abelha et al (2001), there are few tropical species with specialized feeding habits, the majority of which are generalists, with a certain degree of preference but using the resources available in the environment (Pereira et al, 2007).…”

Fish assemblages in two sandy beaches in lower Purus river, Amazonas, Brazil

“…The presence of large numbers of fish predators in sandy beaches has been cited before (GOULDING et al, 1988;PEREIRA et al, 2007), as well as the presence of fishes that prey on recently ecloded turtles (ALHO & PÁDUA, 1982;FACHÍN-TERÁN & VOGT, 2004). Sandy beaches are important sites for turtle-eggs deposition what might be a factor of attraction for these big predators (VOGT, 2008).…”

Comparative Analysis of Distribution of Intertidal Fish Assemblages in Different Estuarine Systems on Northern Coast of Brazil

“…Studies addressing trophic guilds in the tidal creeks in the Maranhense Gulf indicate uniformity in the diet of the fish species caught, mainly because few tropical species have specialized feeding habits (Abelha, 2001). Most species are generalists, with some degree of preference in the use of available resources in the environment (Pereira et al, 2007).…”