08 Aranha Fishes Brazil.Pdf

Rev. Biol. Trop. 46(4): 951-959, 1998 www.ucr.ac.cr Www.ots.ac.cr www.ots.duke.edu Habita! use and food partitioning of the fishes in a coastal stream of Atlantic Forest, Brazil J. M. R. Aranha, D. F. Takeuti & T. M. Yoshimura Depto Zoologia, Setor de Ciencias Biológicas, Universidade Federal do Paraná, CP 19.020, CEP 81531-990, Curitiba, Brasil. Fax: 55 (041)266-2042, E-mail: [email protected] Received 5-II-1998. Corrected22-VI-1998. Accepted 13-VIII-1998. Abstrad: We analysed the fish assemblage in the "Mergulhiio"stream (soulhem Brazil) with underwater obser vations 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 abun dant species were collected from 26 species (lO families). The fish assemblage occupied the bottom stream. The similarity analysis of spalía! occupation ofspecies grouped four habitat use guilds: A) "Iambaris" (Aslyanaxsp. and Deutetodonlangei), Characidium spp. (C. lane; and C. plerosliclum) and Rineloricaria kronei used thebot tom in deep sites and waters with middle current; B) Pimelodella pappenheimi and Corydoras barbalusused 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 seventrophic guilds: Microglanis sp. and PiTMIodellapappen heimi: 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. Key wol'ds: Habitat IIse, feeding, resource partitioning, AtIantic Forest, coastal stream, Brazil. Neotropical freshwater fishes are very would reduce the importance of the competi diverse and fish assemblagesare quite rich in tive relationships (e.g. Connor & Simberloff this regíon. So the interspecific relationships 1979, Strong 1980, Grossman et al. 1982, are intricate in these communities (Lowe Wiens 1977). McConneU 1987). The resource partitioning in a community Sevetal researchers believe that competi may be important to the knowledge of the tion would bean important ecological and evo nature of these interrelationships (Schoener lutionary factor (e.g.· Schoener 1974, Yant et 1974). The most important dimensions of al. 1984). Nevertheless, others believe that the resource partitioning for fishassemblages are environmental instahility of the abiotic factors the habitat and trophic segregation (Ross 952 REVISTA DE BIOLOGIA TROPICAL 1986), being the habitat segregation most large rock (more than 25 cm); 7, litter and 8, important in freshwater than it is in marine trunkand branehes. The shadow of the vegeta environments (Horn 1972). tion cover was recorded by the presence (1) or In Brazil, studies of microhabitat and/or absence (O) of the vegetation itself or branches trophic strueture of freshwater fish assem over the point-sample. blages have been increasing during the last few years, but few studies have been eonducted in eoastal streams (e.g. Costa 1987, Teixeira Direction of Observation 1989, Sabino & Castro 1990). In this paper, the microhabitat use and RightEdge trophic strueture in guilds of the fishes were analysed in a eoastal stream of the Atlantic Forest in Paraná State. MATERIALSAND METHODS 3 The "Mergulhiio" stream is a second order 5m LeftEdge stream Atlantic Forest eoastal stream in Antonina municipality (Paraná S tate, Brazil; F10w water 2S017'S, 48°44'W), with very clear water, which allows underwater observations. In the Fig. l. Location of tbe sample-points in transects for mea studied area the contiguous vegetation is eom surement of variables of habitats and observation of habi posed of trees and shrubs on the left edge and tat use. The grid has ten transects at 5 m intervals. herbaeeous plants on the right. The average depth is one meter, and the average distanee between the edges is 5m. This researehwas eondueted in daylight in The underwater observations were done September and Oetober 1993, and January and with mask and snorkel during 6 min in each Mareh 1994. point-sample, where we noted the number of A grid with ten transeets (adapted from fishes of eaeh species, their distance from the Gorman & Karr 1978; Fig. 1) with 80-130 water's edge and their vertical position. The point-samples was used for measuring four distance from the water's edge was classified habitat variables and for observation of the in three categories: O, nearest to right edge; 1, fishes. The habitat variable measurements mid-stream and 2, nearest to left edge. The were the depth of water, eurrent velocity, bot vertical position was categorized as 1 (upper tom type and shadow of vegetation eover. The third of the water column), 2 (middle third), 3 depth was measured in eentimeters and classi (lower third) and 4 (bottom). fied in eategories of ten of eentimeters (1= 0- During the underwater observation, the 10 em to 9= 80-90 cm). The current velocity feeding behaviour of the species was noted, was measured with a Pitot tube at two cen and grouped using the same foraging tactic timeters under the surface and classified in categories deseribed by Sazima (1986). four categories: 0, imperceptible; 1, slow After the observation, fishes were collect (0.00-0.25m.s-l); 2, moderate (0.25-0.50 m.s-I); ed with fishing-nets, casting nets and sieves to and 3, fast (0.50-0.75 m.s-l). The substrate or study the fish assemblage and their dieto bottom type was classified in eight categoríes: The stomach or samples of the foregut 1, sand; 2, gravel; 3, pebble; 4, stone (less than contents of the most abundant collected 10 cm of diameter); 5, rock (10-25 cm); 6, species (when individuals were over ten) were ARANHA el al.: Habitat use aud food partitioningof the fishesin a coastal stream 953 examined, under estereoscopic microscope The habitat variables that prevails in the and optica! microscope, to assign the feeding "Mergulhao" stream were the sand-type sub guilds by analysis by the occurrence methods, strate(category 1), current velocity ti11 0.5 m.s-1 which the percent composition of each food (categories 1 and 2) and depths between 40 and item in the total number of the items found 60 cm (categories 5 and 6). (Hyslop 1980). The significant differences in the habitat use, by species and by assemblage, in each Data Analysis: Chi-square goodness-of environmental variable category and íts mainly fit-test was used to compare frequency distrib occurrence is showed in Table 2. The habitat utions of habitat use in relation to the avail use by the fish assemblage was significant to ability of each resource. Calculations of vertical position and the tendency to occupy the expected frequencies were based on the envi bottom was corroborated. "Lambaris" tended to ronmental features and the sample sizes were occupy the bottom of deep stretches with mod standardized to a total of 100, as suggested in erate and fast current velocity. Mimagoniates Gorman (1988). For this purpose, we used the microlepis preferred siles in the left edge with data for each species and for all species togeth litter and trunklbranch substrate type, water ero AH species analysis provided an assessment surface and shaded areas. Characidium spp. of how the assemblage used the available preferred water with current more than 0.25 resources. mJs in deeper sites and occupied the bottom in The similarity in the habitat use by species unshaded areas. Pimelodella pappenheimi was estimated by the Morisita's measure occupied the stream bottom in areaswith sand, (Smith & Zaret 1982). A cluster analysis with gravel and litter substratetypes, water with cur UPGMA method (Romesburg 1990) was rent untilI 0.25 m.s-l in unshaded areas with applied using the similarity data. The similari moderate depths. Corydoras barbatus occupied ty of the percent composition of each food item almost exclusively the stream bottom mainly was ca1culated using the Morisita's measure the right edge, in litter and trunklbranch sub modified by Horn (Smith & Zaret 1982) and strate type and waters whose current was lower the results were grouped by UPGMA method than 0.25 m.s-l. Rineloncaria kromei occurred (Romesburg 1990) to determine the feeding in the right edge in unshaded deeper areas with guilds. sand substrate type and water currents moder ate and fast. Phalloceros caudimaculatus occu pied shallow and shaded areas with litter sub RESULTS strate type, and waters with slow current in the right edge of the stream. We collected 26 species belonging to 10 It was not possible to do the x2 test in the families in the "Mergulhao" stream (Table 1). vertical position variable for Characidium The underwater observations totalized 14 spp., Corydoras barbatus and Rineloricaria hours and 2462 observation records of kronei because these species used almost Mimagoniates microlepis, Phalloceros caudi exclusively the stream bottom. maculatus, Corydoras barbatus, Pimelodella The similarity analysis of spatial occupa pappenheimi, Rineloncaria kronei, Astyanax tion of species allowed us to determine four sp., Deuterodon langei, Characidium lanei and groups: "lambaris", Characidium spp. and C. pterostictum. The accurate specific differen Rineloncaria kronei (group A), used the bot tiation of Astyanax sp. and Deuterodon langei tom in deep sites and waters with current more was impossible to do during the observations than 0.25 m.s-l; Pimelodella pappenheimi and and they were treated together and designated Corydoras barbatus (group B), occurred the here by "lambaris".

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