Fish conservation in South America is a pressing issue. The biodiversity of fishes, just as with all other groups of plants and animals, is far from fully known. Continuing habitat loss may result in biodiversity losses before full species diversity is known. In this review, the main river basins of South America (Magdalena, Orinoco, Amazon and Paraná-La Plata system), together with key aquatic habitats (mangrove-fringed estuaries of the tropical humid, tropical semi-arid and subtropical regions) are analysed in terms of their characteristics and main concerns. Habitat loss was the main concern identified for all South American ecosystems. It may be caused by damming of rivers, deforestation, water pollution, mining, poor agricultural practice or inadequate management practice. Habitat loss has a direct consequence, which is a decrease in the availability of living resources, a serious social and economic issue, especially for South American nations which are all developing countries. The introduction of exotic species and overfishing were also identified as widespread across the continent and its main freshwater, coastal and marine ecosystems. Finally, suggestions are made to find ways to overcome these problems. The main suggestion is a change of paradigm and a new design for conservation actions, starting with integrated research and aiming at the co-ordinated and harmonized management of the main transboundary waters of the continent. The actions would be focused on habitat conservation and social rescue of the less well-off populations of indigenous and non-indigenous peoples. Energy and freshwater demands will also have to be rescaled in order to control habitat loss.

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Annulus formation on the scales of the Central Amazonian anastomid fish Schizodon fasciatus was studied with respect to periodic variations in growth rates caused by seasonal inundation or associated biological processes. Monthly samples from fish markets were analysed with regard to marginal scale increment, feeding index, condition factor, gonadosomatic index, and body cavity fat content. There was a significant variation in all indices which was related to seasonal change in water level. Fat storage was related to energy requirements especially during gonad maturation. Fastest growth was observed during the period of falling water level. The formation of scale growth marks corresponded to the period of gonad maturation between January and February. The results indicate the formation of only one single growth mark on scales per year. 1998 The Fisheries Society of the British Isles

The presence of researchers from Western (i.e., developed world) institutions in Amazonia has frequently been contentious due to fears of 'scientific imperialism' or suspicions that they may be exerting undue influence over research agendas and knowledge production to the detriment of local researchers. Such negative perceptions are widespread, but not well substantiated. A more nuanced understanding of these issues requires information on who is conducting research in Amazonia and how knowledge production has changed over time. We performed a bibliometric analysis on Thomson Reuters'ISI Web of Science of all research articles about the Amazon published in three time periods: 1986-1989, 1996-1999, and 2006-2009. We found that the number of articles published and the diversity of countries involved in Amazonian research increased dramatically over the three time periods. The representation of several Amazonian countries-especially Brazil-increased, while the proportion of articles without a single author from an Amazonian country also increased. The results indicate that the research capacity of Amazonian countries has increased, but that leadership of high-impact projects may still largely reside with researchers from developed countries.Abstract in Portuguese is available in the online version of this article.

Drip‐tips are a common feature of the leaves of rain forest trees, but their functional significance remains contested. The most widely accepted hypothesis is that drip‐tips assist drainage of the lamina thereby aiding drying of the leaf surface and reducing the rate of colonization and abundance of epiphyllic organisms. The drying action of drip‐tips may also enhance transpiration and reduce the need for investment in support structures. Furthermore, drip‐tips may help prevent splash erosion around the base of the tree. Data from 130 forest Amazonian plots are used to investigate the abundance and distribution of drip‐tips and, through regression methods that incorporate spatial autocorrelation, seek to identify associations between the frequency of drip‐tips and a range of climatic variables. The average frequency of species and trees with drip‐tips across all plots was 32 and 33 percent, respectively. Trees and species with drip‐tips were significantly more prevalent in the Central‐East Amazon than the other regions. Drip‐tips were also associated with tree species that have smaller maximum heights and with trees with smaller trunk diameters. The proportion of species and individuals with drip‐tips was more strongly correlated with precipitation of the wettest trimester than with total annual precipitation or length of the dry season. Our results extend and provide support for both existing hypotheses for the functional benefit of possessing a drip‐tip. Moreover, the currently unrecognized macrogeographic association between the frequency of drip‐tips in trees of the tropical forest understory and areas of heavy precipitation suggests a new function for this trait.

The objective was to study seasonal aspects of the piracatinga catfish (Calophysus macropterus) growth and its relationship with the flood pulse. Analyzed from June 1997 to May 1998 were 446 specimens from the Amazon River. Using the period regression model with several biometric indexes gave the following results: two periods of low growth were identified in the vertebrae of C. macropterus, the first during falling water (August) and the second during rising water (January), using marginal increment analysis (MIA). This pattern was also observed in the annual variation of the regression coefficient of the length-weight relationship (b), and Feeding Index (FI), but an inverse relationship was observed with the Maturity Index (MI). These results suggest that reproduction occurs from January to February in the rising water season, when C. macropterus reaches sexual maturity at 1.4 and 1.5 of age for females and males, respectively. The parameters of BertalanffyÕs model were SL = 40.05[1)e )0.44(t)0.37) ] for females and SL = 41.9[1)e )0.42(t)0.36) ] for males. Natural mortality was high ($:0.42-#:0.40) and longevity low ($:6.8-#:7.1 years). The present study demonstrates that seasonal growth in C. macropterus is correlated with the flood pulse, especially in periods of rising and falling waters. These results, analyzed by the periodic regression model, showed that reproduction, migration or changes in feeding behavior have relationships with annulus formation in hard structures in this species. All quantitative indexes show clear seasonal variation to be correlated with river water level fluctuations.