Stream fish communities and their associations to habitat variables in a rain forest reserve in southeastern Brazil

Abstract

SynopsisThis paper describes the spatial variability of fish communities and identifies patterns of association between fish communities and habitat variables, including anthropogenic factors. We sampled streams inside and in the surroundings of a rain forest reserve in the southeast of Brazil in the rainy season. We could distinguish three main groups of streams: upland streams (draining the upland, flat portions of the mountain ridge of Serra de Paranapiacaba), adventitious streams of clearwater mountain torrents (small streams draining confined valleys in the slopes of this sierra), and large streams of clearwater mountain torrents (relatively unconstrained large streams close to the foots of the mountains). Despite the high variability of fish communities associated with these streams we identified some patterns using exploratory statistical analyses. These patterns were corroborated by additional field observations and information from the scientific literature. The main differences in fish community composition and diversity among the three groups of streams are probably related to large-scale factors such as elevation and position of the stream in the watershed. However, differences within these three groups seem to be mostly due to site-specific factors. Differences of instream characteristics are likely to be caused by natural variability of the ecosystems but also, in some cases, by human disturbances like pollution from human settlements, agriculture and mining.

Ichthyofauna of Rio Jurubatuba, Santos, São Paulo: a high diversity refuge in impacted lands

“…The Margalef Diversity Index calculated for the whole study area was 3.15, while this value was 2.33 and 1.76 in Rio Jurubatuba and Riacho Sabão, respectively, when these streams are considered separatedly. These values are in accordance to what Gerhard et al (2004) registered for the Rio Ribeira de Iguape system, with their highest value (3.14) obtained in the Rio Iporanga watershed. The Simpson Dominance Index values were 0.31 for the whole area and 0.37 and 0.27 for Rio Jurubatuba and Riacho Sabão alone, respectively.…”

“…The high number of endemic fish species in the coastal rivers of the Atlantic Forest is an aggravating factor in respect to the conservation policies of these areas as this biome is located in the most populated regions of the country, making these rivers especially vulnerable to anthropogenic impacts (Bizerril 1994, Mazzoni & Lobón-Cerviá 2000, Gerhard et al 2004.…”

Hydrologic connectivity driven natural stream fish assemblages in mountain streams in the Yangtze River basin: implications for stream fish conservation in monsoonal East Asia

“…Under natural conditions, patterns and processes observed in fish assemblages are strongly influenced by multiple factors operating over a range of spatial and temporal scales (Horwitz, 1978;Schlosser, 1987;Tonn, 1990;Oberdoff et al, 1995;Ostrand & Wilde, 2002;Hoeinghaus et al, 2007). On a local scale, physical and chemical factors appear to determine species richness in variable environments (Gorman & Karr, 1978;Rahel, 1986;Schlosser, 1991;Matthews, 1998;Bond & Lake, 2003;Gerhard et al, 2004), while biological ones are more important in stable environmental conditions (Ross et al, 1985;Grossman et al, 1990). On larger spatial scales, physical factors such as spatial position within the drainage network (Osborne & Wiley, 1992;Grenouillet et al, 2004;Smith & Kraft, 2005), river size (Livingstone et al, 1982;Hugueny, 1989), climate (Hughes & Gammon, 1987), along with historical factors (e.g., speciation and dispersal) (Oberdoff et al, 1995), co-determine the composition of available species from which local communities are assembled.…”

Effects of land use on fish assemblages in Patagonian low order streams

“…Conversion of native forest into pastures as a consequence of land use for agriculture has produced a wide-scale degradation of aquatic ecosystems in several countries (Heartsill-Scalley and Aide, 2003;Gerhard et al, 2004;Lorion and Kennedy, 2009). This land use practice affects freshwater systems by increasing the runoff of silt, fertilizers, and pesticides, whereas removal of large volumes of water for irrigation often reduces habitat availability, and increases salinity.…”