Thropic Levels Funtional

Hydrobiologia (2006) 556:251–264 DOI 10.1007/s10750-005-1255-5

Ó Springer 2006

Primary Research Paper

Trophic levels and functional feeding groups of macroinvertebrates in neotropical streams
Sylvie Tomanova1,2,*, Edgar Goitia3 & Jan Helesˇ ic1
Laboratory of Running Waters Biology, Department of Zoology and Ecology, Masaryk University, Kotla´rˇska´ 2, 61137, Brno, Czech Republic 2 UR131 Institut de Recherche pour le De´veloppement, ULRA UMSS, Cochabamba, Bolivia 3 ´ticos (ULRA), Universidad Mayor de San Simo´n, Cochabamba, Bolivia Unidad de Limnologı´a y Recursos Acua (*Author for correspondence: E-mail: sylvatom@seznam.cz)
Received 7 March 2005; in revised form 16 June 2005; accepted 22 July 2005
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Key words: diet, feeding groups, macroinvertebrates, neotropical streamsAbstract Feeding strategies are typical traits reflecting the adaptation of species to environmental conditions. This concept is currently developed in some water quality systems (e.g. Index of Trophic completeness) and the structure of functional feeding groups (FFGs) could form part of a unified measure across communities differing in taxonomic composition. However, in South America, informationabout the FFG classification of invertebrates in streams is almost absent and existing studies using FFG structure follows classification from North America. But even taxonomically related species may have different diets in tropical and temperate areas and therefore, studies about FFG structure in neotropics could be biased. For this reason, we determined diet composition, trophic level and FFGs,using gut contents analysis and mouthpart observations of 49 macroinvertebrate taxa (mostly at genus level) from neotropical streams. We observed that practically all macroinvertebrates fed upon fine detritus which indicates the importance of this food resource in neotropical streams. As the assignment to a single FFG does not accurately reflect the functional profile of taxa, we transcribed theaffinity of taxa to each FFG using fuzzy codes. Finally, we published the coding of diet composition and FFG of the taxa examined, which could be used in future community analyses of lotic ecosystems in the Neotropical zone.

Introduction Tropical rivers support a rich but incompletely known biota. Therefore, the principal topic of studies in the Neotropical zone is biodiversity, taxonomic descriptionsand the distribution of new species (Jackson & Sweeney, 1995). Besides, an important effort should also be made to develop realistic models of the structure and functioning of natural tropical streams. Since ecological information about tropical species is very scarce, fundamental research on this subject is necessary.

Ecological functions can be described by a multitude of general biologicaltraits that reflect the adaptation of species to environmental conditions (Townsend & Hildrew, 1994). Feeding strategies are typical traits reflecting the adaptation of species and they could form part of a unified measure across communities differing in taxonomic composition (Statzner et al., 2001). Functional feeding classification of aquatic organisms enhances the knowledge of trophic dynamics instreams by simplifying the benthic community into trophic guilds – functional feeding groups (FFGs) (Cummins, 1995). In the temperate

252 zone, the pattern of FFG distribution has been related to the environmental gradient in the river (River Continuum Concept – Vannote et al., 1980) and is currently used in some water quality systems (e.g. Index of Trophic completeness – Pavluk et al., 2000; Bijde Vaate & Pavluk, 2004). In South America, exact information about the FFGs of aquatic invertebrates is lacking and the existing studies using FFGs are mainly based on the North American classification (e.g. from Merritt & Cummins, 1996). However, the highly flexible life histories and mobility that seem to characterize many neotropical stream taxa may well influence their flexibility in obtaining...