Length-weight relationships (LWR) were estimated for 17 species and total length at first maturity (L50) for three species of freshwater fishes from the Miranda River, southern Pantanal, Brazil. The b values were compared for some species in the Paraguay River basin with the northern (Cuiaba´River) part of the basin; differences in length-weight relationships were significantly different for Pseudoplatystoma corruscans, P. reticulatum (syn. P. fasciatum). First references on L50 and LWR are presented for two and eight fish species, respectively, as well as the new maximum total length for two species.

Ecological literature offers a myriad of methods for quantifying β diversity. One such method is determining BD total (BD), which, unlike other methods, can be decomposed into meaningful components that indicate how unique a sampling unit is regarding its composition (local contribution) and how unique a species is regarding its occurrence in the community (species contribution). Despite this advantage, the original formulation of the BD metric only assesses taxonomic variation and neglects other important dimensions of biodiversity. We expanded the original formulation of BD to capture variation in the functional and phylogenetic dimensions of community data by computing two new metrics-BD Fun and BD Phy-as well as their respective components that represent the local and species contribution. We tested the statistical performance of these new metrics for capturing variation in functional and phylogenetic composition through simulated communities and illustrated the potential use of these new metrics by analyzing β diversity of stream fish communities. Our results demonstrated that BD Phy and BD Fun have acceptable type I error and great power to detect the effect of deep evolutionary relationships and attributes mediating patterns of β diversity. The empirical example illustrated how BD Phy and BD Fun reveal complementary aspects of β diversity relative to the original BD metric. These new metrics can be used to identify local communities that are of conservation importance because they represent unique functional, phylogenetic, and taxonomic compositions. We conclude that BD Phy and BD Fun are important tools for providing complementary information in the investigation of the structure of biological communities.

In

Biodiversity is inherently multidimensional in nature, differences in evolutionary history, attributes of species, taxonomic composition constitutes a small fraction of whole variation present in this multidimensional space. Despite its multidimensional characteristic, biodiversity has been traditionally measured by assessing its dimensions separately through metrics of diversity. However, assessing multiple dimensions in a common framework opens the possibility of answering interesting questions that, until now, are poorly understood, such as: What dimensions capture most of the variation present in biodiversity among communities? We assess this question by extending the framework of Importance Values (IVs) to three dimensions of variation in biodiversity, functional, taxonomic and phylogenetic, and evaluate which of these captures the most variation in biodiversity space. To address this question we used data from stream fish communities of the Ivinhema River Basin in Brazil. We found that functional and phylogenetic dimensions are more important than the taxonomic dimension (represented by richness) in capturing variation in the biodiversity space formed by these three dimensions together. Furthermore, the IVs of these three dimensions were similar along an altitudinal gradient, indicating similar contributions by a given dimension in different environmental conditions. We highlight the importance of adopting a multidimensional approach when describing biodiversity, since richness (the proxy for taxonomic dimension), despite being the most commonly used, is an incomplete surrogate to capture the variation present in the biodiversity space of stream fish communities.

During the study of metazoan parasites of freshwater fish in the Pantanal wetland (state of Mato Grosso do Sul, Brazil), third-stage larvae of Brevimulticaecum sp. were collected from the abdominal cavity, liver parenchyma, mesentery, skeletal muscles and stomach wall of the following species: Gymnotus inaequilabiatus, Hemisorubim platyrhynchos, Hoplias aff. malabaricus, Myleus levis, Pseudoplatystoma corruscans, Pygocentrus nattereri, Serrasalmus marginatus and Sorubim lima. The larvae exhibited the main characteristics of the genus Brevimulticaecum, such as short ventricular appendices and the position of excretory pore and excretory nucleus. This is the first report and description of larval specimens of Brevimulticaecum parasitic in these hosts, which are fish species distributed throughout South America.

Aim: This study aimed to evaluate influence of hydrological variation, ontogeny and interspecific variation in the feeding activity and diet composition for P. nattereri and S. marginatus in floodplain of Negro River, South Pantanal. Methods: The samples were taken with the use of gillnets and cast nets of different sizes, from October/2005 to August/2008. Results: We sampled 748 specimens, 442 of P. nattereri and 306 of S. marginatus. We identified 31 items in the dry and 14 in the flood season for P. nattereri, and 29 items in the dry and eight in the flood season for S. marginatus. For both species, fish was the predominant food item in both seasons. The PERMANOVA results showed that the diet varied significantly between the two species (p<0.001), during ontogenetic development (p<0.001) and seasonally (p=0.024). The ancova results suggests that the intensity of food intake was higher in the dry season (p<0.001) for both species. The niche breadth varied only between studied species with S. marginatus presenting higher niche breadth than P. nattereri. Conclusion: Piranhas feed more during dry season, probably because in this period food is more varied and abundant, due to the concentration of fish in the main river channel. There were ontogenetic changes in the diet, with no feeding overlap between the two species, probably because of differences in preference for some items and differences in feeding behavior displayed during hunting attacks.Keywords: Serrasalminae, diet, feeding overlap, trophic ontogeny, Nhecolândia.Resumo: Objetivos: Este trabalho tem como objetivo avaliar a influência da variação hidrológica, da ontogenia e da variação interespecífica na atividade alimentar e composição da dieta de P. nattereri e S. marginatus na planície de inundação do Rio Negro, Pantanal Sul. Métodos: As amostragens foram realizadas com o uso de redes de espera e tarrafas com diversas malhagens no período de outubro/2005 e agosto/2008. Resultados: Foram coletados um total de 748 indivíduos, 442 de P. nattereri e 306 indivíduos de S. marginatus. Identificamos 31 itens alimentares no período da seca e 14 na cheia para P. nattereri e 29 itens alimentares no período da seca e oito na cheia para S. marginatus. Para ambas as espécies, peixes foi o item predominante em ambas as estações. Os resultados da PERMANOVA mostraram que a dieta variou significativamente entre as espécies (p<0,001), durante o desenvolvimento ontogenético (p<0,001) e sazonalmente (p=0,024). Os resultados da ANCOVA sugerem que a intensidade da tomada de alimento foi maior na estação seca (p<0,001), para ambas as espécies. A amplitude de nicho 382 Ferreira, FS. et al.Acta Limnologica Brasiliensia variou entre as espécies estudadas, S. marginatus apresentou uma amplitude de nicho maior do que P. nattereri. Conclusão: As piranhas se alimentam mais durante a seca, provavelmente porque neste período o alimento é mais variado e abundante, devido a concentração de peixes no canal principal do rio. Houve mudanças ontogenéticas na dieta, sem sobreposiç...

RESUMONo presente trabalho foram analisados os parâmetros de crescimento, a relação peso-comprimento e a influência da variação sazonal do rio Miranda, alto rio Paraguai, sobre o período reprodutivo de Prochilodus lineatus. As amostragens foram realizadas mensalmente entre abril/2000 e outubro/2003. A equação que descreve a relação peso-comprimento total para fêmeas foi Pt=0,01213*Ct 3,039 e para os machos Pt=0,01322*Ct 3,012 . O comprimento total assintótico estimado foi de 55,68cm e taxa de crescimento K = 0,46/ano e Rn = 0,183 foram estimados pela frequência de classes de comprimento. O tamanho de primeira maturação (L50) foi estimado em 28,2cm. O índice gonadossomático (IGS) variou significativamente entre os meses (H = 136,61; p < 0,01), com valores mais elevados entre setembro e dezembro, contudo foram encontradas fêmeas maduras de agosto a fevereiro. O IGS esteve positivamente correlacionado com a duração do dia (rs = 0,55; p < 0,05) e com a precipitação (rs = 0,65; p < 0,05), contudo, não esteve correlacionado com o nível do rio (rs = 0,48; p = 0,1), ainda que no período de enchente seja perceptível a co-variação entre GSI e o nível do rio. O aumento no comprimento do dia e o início das primeiras chuvas parecem atuar como sinais preditores para que as fêmeas possam iniciar a atividade reprodutiva, a fim de garantir aos ovos e larvas as condições ambientais ideais encontradas nos meses subsequentes de cheia, fato este verificado pela alta proporção de fêmeas maduras de setembro a dezembro. A expectativa de vida de 6,5 anos foi compatível com as 6 coortes estimadas pela curva de crescimento. Palavras-chave: tamanho de primeira maturação; crescimento; Pantanal. ABSTRACT POPULATION STRUCTURE, BREEDING SEASON AND GROWING OF Prochilodus lineatus INHEADWATER OF MIRANDA RIVER, UPPER PARAGUAI RIVER. In the present paper we analyzed growth parameters, length-weight relationship and the influence of seasonal variation of Miranda river, upper Paraguay River, on breading season of Prochilodus lineatus. The samples were accomplished monthly from April/2000 to October/2003. The length-weight relationship described for females was PT=0.01213*CP 3.039 and for males was PT=0.01322*Ct 3.012 . The estimated asymptotic total length was 55.68cm and the growth rate K = 0.46 and Rn = 0.183 were estimated by frequency of length classes. The estimated size at first maturity (L50) was 28.2cm. The gonadossomatic index (GSI) varied significantly among months (H = 136.61; p < 0.01), with significant higher values from September to December, however ripe females were caught from August to February. GSI was positively correlated with the day length (rs = 0.55; p < 0.05) and with rainfall (rs = 0.65; p < 0.05), however, it was not correlated with the river level (rs = 0.48; p = 0.1). The increasing in the duration of the day and the begin of the first rains seem to act as cues for females start the breeding activity, in order VICENTIN, W. et al. Oecol. Aust., 16(4): 891-904, 2012 892 to provide to eggs and larvae the optimum environmen...

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