Trophic strategy of Atlantirivulus riograndensis

Neotropical Ichthyology
On-line version ISSN 1982-0224
Neotrop. ichthyol. vol.14 no.1 Maringá  2016  Epub Apr 14, 2016

http://dx.doi.org/10.1590/1982-0224-20150068
ARTICLES

Trophic strategy of Atlantirivulus riograndensis (Cyprinodontiformes: Rivulidae), a non-annual rivulid threatened by extinction, in a perennial environment, Brazil.

Laísa Wociechoski Cavalheiro1 , Clarice Bernhardt Fialho1 1Universidade Federal do Rio Grande do Sul, Departamento de Zoologia, Programa de Pós-Graduação em Biologia Animal, Avenida Bento Gonçalves 9500, Prédio 43435, CEP 91501-970 Porto Alegre, RS, Brazil. (LWC) isa_woci@hotmail.com (corresponding author), (CBF) cbfialho@via-rs.net

ABSTRACT

Rivulidae includes non-annual fish of perennial habitats and annual fish of temporary wetlands. The objective of this research was to investigate the trophic strategy of Atlantirivulus riograndensis in a perennial environment. Sampling occurred in an environmental conservation unit in the Pampa biome, Brazil. Quantification of the diet followed the volumetric method. Consumption of autochthonous material as the main food source of the species followed the pattern of Rivulidae. Species is zooplanktonic when young. Food spectrum is broadened and insectivorousness increases with ontogeny, revealing a specialist trend in the feeding strategy of A. riograndensis. The most diverse feeding occurs in the spring and summer seasons in which the presence of larger fish was more frequent than in other seasons. The increased consumption of microcrustaceans in the fall was related to smaller individuals, captured in greater quantities in this post-reproductive period. The lowest diversity of dietary items occurs during the winter and may reflect the lower diversity of food resources available in this season or the transition from juvenile to adult diet, with consumption of autochthonous Diptera by medium sized fish.

Key words: Autochthonous resources; Ontogeny; Seasonality; Specialist; Trophic pattern








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