Abstract
We analysed the fish assemblage in the "Mergulhiio" stream (soulhem Brazil) with underwater observations for habitat use, considering water depth, current velocity, bottom type, shadow froID vegetation cover, distance of stream-edge, and vertical position. Stomach contents or foregut content samples of the most abundant species were collected from 26 species (lO families). The fish assemblage occupied the bottom stream. The similarity analysis of spalía! occupation of species grouped four habitat use guilds: A) "Iambaris" (Aslyanax sp. and Deutetodon langei), Characidium spp. (C. lane; and C. plerosliclum) and Rineloricaria kronei used the bottom in deep sites and waters with middle current; B) Pimelodella pappenheimi and Corydoras barbalus used the bottom in siles with JOwer cUI'l"ént; C) Mimagoniates microlepis used the surface of the water column; and D) Phalloceros caudimacullUus used shallow sítes and waters without current. Species with few records were analysed descriptively. Diet similarity suggested seven trophic guilds: Microglanis sp. and PiTMIodella pappenheimi: omnivorouslca:mivorous gui14; Corydoras barbatus: omnivorous/insectivorous guild; Characidium [ane;: aquatic insectivorous guild, Ilillinly aquatic insects; Mimagoniates microlepis: terrestriál insectivorous guild, mainly te.rrestrial insects; Deuterodon [angei and ASlyanax sp.: omnivorous/herbivorous guild; Rineloricaria kronei, Kronichth.yssubteres, Schizolecis guntheri. Hisonotus leucofrenatus and Pseudotothyris obtusa: herbivÓfous guild; and PhaUoceros caudimaculatus: a!givorous guild. When the guilds were similar, the species were geÍletalists in diet and in habitat use.
Highlights
[ane;: aquatic insectivorous guild, Ililnli ly aquatic insects; Mimagoniates microlepis: terrestriál insectivorous guild, mainly te.rsre trial insects; Deuterodon [angei and ASlyanax sp.: omnivorous/herbivorous guild; Rineloricaria kronei, Kronichth.yssubteres, Schizolecis guntheri
In Brazil, studies of microhabitat and/or trophic strueture of freshwater fish assem blages have been increasing during the last few years, but few studies have been eonducted in eoastal streams (e.g. Costa 1987, Teixeira 1989, Sabino & Castro 1990)
C. lanei and C. pterostictum were treated as Characidium spp
Summary
The "Mergulhiio" stream is a second order stream Atlantic Forest eoastal stream in Antonina municipality (Paraná State, Brazil; 2S017'S, 48°44'W), with very clear water, which allows underwater observations. The average depth is one meter, and the average distanee between the edges is 5m. This researeh was eondueted in daylight in September and Oetober 1993, and January and Mareh 1994. A grid with ten transeets (adapted from Gorman & Karr 1978; Fig. 1) with 80-130 point-samples was used for measuring four habitat variables and for observation of the fishes. The habitat variable measurements were the depth of water, eurrent velocity, bot tom type and shadow of vegetation eover. The current velocity was measured with a Pitot tube at two cen timeters under the surface and classified in four categories: 0, imperceptible; 1, slow (0.00-0.25 m.s-l); 2, moderate (0.25-0.50 m.s-I); and 3, fast (0.50-0.75 m.s-l). The substrate or bottom type was classified in eight categoríes: 1, sand; 2, gravel; 3, pebble; 4, stone (less than 10 cm of diameter); 5, rock (10-25 cm); 6,
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