RESUMO É iminente que o Brasil desenvolva ferramentas para monitorar o sistema de áreas protegidas do país, formado especialmente pelas Unidades de Conservação e tendo como foco a proteção efetiva da biodiversidade. Nesse contexto, esse trabalho discute métricas de referência (ou linhas de base) para compor um Índice de Integridade Biótica (IIB) baseado nas comunidades de peixes, tendo como área de estudo o Parque Nacional do Pantanal Matogrossense. Os hábitats encontrados no Parque foram agrupados em quatro estratos ambientais: rios, corixos (cursos d´água que se conectam à planície de inundação) e baías permanentes e temporárias. As coletas de peixes foram realizadas em 12 pontos amostrais durante o período seco (out/nov de 2010 e 2011). Foram identificadas 146 espécies de peixes, totalizando 18.954 exemplares coletados em amostragens padronizadas. Não houve associação entre a estrutura da comunidade e os estratos ambientais, sugerindo homogeneidade de hábitats. O IIB final foi composto por nove métricas, a maior parte alocada na classe excelente de integridade biótica, poucas na classe regular e nenhuma na classe pobre. Não houve diferença significativa no IIB entre os dois anos consecutivos. Esses resultados oferecem subsídios técnicos para a tomada de decisão sobre a gestão das áreas alagáveis no Pantanal brasileiro.

ABSTRACT Considering the need for the Brazilian government to develop tools for environmental monitoring for biodiversity conservancy purposes in the national protected areas system, this paper focuses on determining reference site metrics (or baselines) for adapting the Index of Biotic Integrity (IBI) based on the fish assemblages in the Pantanal National Park (PNP). The habitats in the PNP were grouped into four categories: main rivers, corixos (channels connecting the floodplain), permanent bays, and temporary bays. Fish samplings were performed at 12 points during the dry season (Oct-Nov 2010 and 2011). 146 fish species were identified from the total 18,954 individuals collected with standardized fishing gear. There was no association between the structure of the fish assemblage and categories, suggesting a theory on homogeneity of habitats. The final IBIPNP consists of nine metrics, most of them were framed in excellent class, some in fair, and none in poor. There was no significant difference in IBIPNP scores between the two sampled years. This approach provides a direct application for wetland management purposes.

ABSTRACT We evaluated how seasonality affects the frequency and intensity of fin-nipping, as well as the fish prey preferences of Serrasalmus maculatus Kner, 1858. The study took place in a small reservoir of the Ribeirão Claro River basin, state of São Paulo, southeastern Brazil. Fish were sampled monthly from July 2003 to June 2004, using gillnets. Sampling consisted of leaving 50 m of gillnets in the water for approximately 24 hours each month. No seasonal variation in the frequency and intensity of fin-nipping was observed. Among six prey species, piranhas displayed less damage in their fins, possibly due to intraspecific recognition. Under natural conditions, the caudal fins of Cyphocharax modestus (Fernández-Yépez, 1948) were the most intensively mutilated, which suggests multiple attacks on the same individual. The size of individuals in this species was positively correlated with the mutilated area of the fin, whereas no such correlation was observed for Astyanax altiparanae Garutti & Britski, 2000 and Acestrorhynchus lacustris (Lütken, 1875). The high number of mutilated fish under natural conditions strongly suggests that the relationship between S. maculatus and its prey is more akin to parasitism than to predation. If mutilated fins negatively affect the ability of prey to swim, the spread of S. maculatus might result in an unnatural impact on prey fish assemblages and population structure after damming.

RESUMO Neste trabalho nós determinamos a composição da dieta, periodicidade reprodutiva e fecundidade de Astyanax intermedius em um riacho de cabeceira de um Parque Estadual de Mata Atlântica. Avaliamos também a influência da chuva, temperatura da água e tamanho do peixe na amplitude e sobreposição de nicho. As amostragens foram realizadas mensalmente ao longo de um ano no riacho Ribeirão Grande, sudeste do Brasil. A dieta consistiu de 31 itens, com igual contribuição de itens alóctones e autóctones. As fêmeas foram maiores do que os machos e os comprimentos médios de primeira maturação foram de 4,44 cm e 3,92 cm, respectivamente. Com base nos 212 pares de ovários analisados, o número de ovócitos por fêmea variou de 538 a 6727 (média = 2688,7). A amplitude e a sobreposição de nicho não foram relacionadas à chuva e temperatura da água, e somente a amplitude de nicho aumentou com o tamanho do peixe, sugerindo que conforme o crescimento, mais itens são incluídos na dieta. Nossos resultados sugerem que A. intermedius apresenta um comportamento típico de espécie oportunista, o que pode explicar a prevalência desta espécie em diversos riachos de cabeceiras isolados de Mata Atlântica onde os recursos alimentares são abundantes e distribuídos ao longo do ano.

ABSTRACT In this paper, we determined diet composition, reproductive periodicity and fecundity of Astyanax intermedius in a headwater stream of a State Park of an Atlantic rainforest. We also evaluated the influence of rainfall, water temperature and fish size on niche width and niche overlap. Sampling was conducted monthly throughout one year in the Ribeirão Grande stream, southeastern Brazil. Diet consisted of 31 food items with equal contribution of allochthonous and autochthonous items. Females were larger than males, and the mean sizes at first maturation were 4.44 cm and 3.92 cm, respectively. Based on 212 pairs of mature ovaries, the number of oocytes per female ranged from 538 to 6,727 (mean = 2,688.7). Niche width and niche overlap were not related to rainfall nor water temperature and only niche width increased with fish size, suggesting that as fish grow, more items are included in diet. Our results suggested that A. intermedius fit as a typical opportunistic strategist which may explain the prevalence of this species in several isolated headwater basins of vegetated Atlantic forested streams where food resources are abundant and distributed throughout the year.