Rapid survey of ichthyofauna from rivers and streams of coastal hydrographic regions of Santa Catarina state, Brazil

The lack of knowledge on the distribution and taxonomy of ichthyofauna from coastal Atlantic Rainforest of Santa Catarina state, Brazil, is noteworthy. This study presents a rapid but comprehensive survey of fish species from the coastal hydrographic regions of Santa Catarina. The samples were conducted in October 2012, in 19 sampling sites of five hydrographic regions, using sieves, seine nets, and throw nets. A total of 1,878 individuals belonging to 51 species distributed in 16 families are reported; four freshwater fish species represent distribution novelties for the region. The families Characidae and Loricariidae were predominant, mainly due to the abundance of Astyanax sp., Mimagoniates microlepis, Epactionotus itaimbezinho, and Pareiorhaphis stomias. Therefore, this study provides important contributions to the knowledge of the freshwater fishes from the studied area.

Habitat use and food partitioning of the fishes in a coastal stream of Atlantic Forest, Brazil

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.

Reproduction period of Mimagoniates microlepis, from an Atlantic Forest Stream in Southern Brazil

Mimagoniates microlepis was collected between January and December/2002. Three sample points were chosen at higher, medium and lower portions of Ribeirão river, located at the east of Paraná state. The reproduction period was observed by the frequency of gonad developmental stages, variation of the gonosomatic relation (RGS) and gonad condition (K). The average length at the first sexual maturity (L50) and the average length when 100% of individuals were adults (L100) were calculated. The intensity of the reproductive activity (IAR) was estimated at each sample point. The reproduction period started in the winter and ended at the end of spring. The high values of IAR encountered demonstrated that the reproductive activity occurred in the whole study area, mainly at the middle portion of the river. Apparently M. microlepis synchronize its fecundation and spawning with the rain regimes using the most suitable times for the cospecific encounters and offspring survival.

Estrutura populacional de Mimagoniates microlepis (Steindachner, 1876) (Characidae, Glandulocaudinae) em um riacho de Floresta Atlântica, Paraná (Brasil)

Estrutura populacional de Mimagoniates microlepis (Steindachner, 1876) (Characidae, Glandulocaudinae) em um riacho de Floresta Atlântica, Paraná (Brasil)

Análise comparativa e aspectos ecológicos da reação de alarme em duas espécies de Mimagoniates (Ostariophysi, Characidae, Glandulocaudinae)

É proposta uma nova metodologia para o estudo das reações de alarme em peixes, utilizada aqui no estudo da "Schreckreaktion" de Mimagoniates lateralis (Nichols, 1913) e Mimagoniates microlepis (Steindachner, 1876), cujos resultados foram contextualizados à ecologia das espécies. O método baseia-se na interpretação cartesiana do comportamento, em que três baterias experimentais distintas são analisadas de forma segmentada nos eixos horizontal e vertical. Os dados foram analisados por estatística não-paramétrica e pela análise de dados longitudinais, a qual permite a interpretação gráfica de séries temporais, e integrados com os estados de agregação dos cardumes pelo uso de índices. A análise conjugada de todos os fatores permitiu uma mensuração menos subjetiva da intensidade de reação. Os resultados para o eixo horizontal não foram conclusivos e os do eixo vertical demonstraram significativas diferenças comportamentais entre baterias e espécies. Mimagoniates lateralis (Nichols, 1913) apresentou indivíduos mais estressados e agregados, com cardumes mais ao fundo, enquanto M. microlepis aparentou maior adaptabilidade às condições experimentais. Ambas as espécies demonstraram reação de alarme nítida, sendo que M. lateralis a apresentou cerca de três vezes mais intensa, em que demonstrou maior coesão dos cardumes e maiores período e amplitude de reação, o que é coerente com seu status de espécie endêmica e ameaçada.

Feeding ecology of stream-dwelling fishes from a coastal stream in the Southeast of Brazil

The relationship between ontogenetic variation of intestine length and feeding habits of five stream-dwelling fish species from the Ubatiba River were investigated. Analysed data were based on two size categories (juveniles and adults) and two food categories (animal and vegetal). Diet composition of each size category revealed that Astyanax janeiroensis and Geophagus brasiliensis changed food preference throughout ontogeny and switched from omnivorous/carnivorous to omnivorous/herbivorous and from omnivorous/carnivorous to omnivorous, respectively. These changes were followed by ontogenetic changes in the Intestinal Coefficient (IC). No ontogenetic differences were registered for IC and food categories consumed by Hoplias malabaricus but significant differences in the size of consumed preys as well as positive correlation between fish size (predator) and prey size was observed. Food items (within animal category) consumed by the adult Pimelodella lateristriga were mainly based on allochthonous arthropods whereas juvenile individuals fed with the same intensity on allochthonous and autochthonous arthropods; both juveniles and adult individuals of Mimagoniates microlepis were mainly allochthonous feeders. Mean IC values of Pimelodella lateristriga and Mimagoniates microlepis did not change along body growth. Although changes in food category consumption were not common among all the studied species, changes in the resource exploitation strategy was a rule among them, except for Mimagoniates microlepis.