

@mastersthesis {6274,
	title = {Diversity, distribution and community structure of electric fishes ({Gymnotiformes}) in the channels of the {Amazon} {River} system, {Brazil}},
	year = {1995},
	note = {9600606},
	school = {Duke University},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {Community assemblages of gymnotiform electric fishes inhabiting the main channels of the Brazilian Amazon River and 11 of its larger tributaries were studied to determine species composition, diversity, distribution and community structure. Electric fish distributions were examined for possible correlations with environmental factors. Comparisons were performed at three different scales: locally, at particular sites along the Amazon; along the Amazon River and its tributaries; and across three large rivers (Amazon, Negro and Orinoco Rivers). In 1992 and 1993, samples of fishes were collected at 36 stations with small 3 m trawl nets hauled at depths from about 2 m to 40 m. Overall, forty species of electric fishes were collected: 25 species of Apteronotidae, 8 Sternopygidae, 5 Rhamphichthyidae and 1 Hypopomidae. The 36 stations were mostly located at sites in and near tributary confluences with the Amazon mainstem. Statistically significant differences in species diversity were detected for stations within sites. Electric fish species diversity tends to increase in the mainstem below tributary mouths. Analyses of species compositions (using non-metric multidimensional scaling and cluster analysis based on Jaccard similarity indices) show distinctness of the faunas of the Coari and Tefe Rivers, and a tendency for faunal distinctness of mainstem stations above tributaries. Detrended Correspondence Analysis of species abundances revealed significant variation in the electric fish assemblage structure among stations, and associations of this variation with sites and depth. Geographical distance was not a good predictor of assemblage structure. Detrended Canonical Correspondence Analysis suggests that electric fish distributions are related to alkalinity, pH, silicates and drainage basin area. These factors are greatest in white-water rivers that have assemblages dominated by apteronotids. Electric fish assemblages of the Negro, Coari, Tefe and Jutai Rivers are positively correlated with high transparency and dissolved organic carbon. Other stations with clear or black-water were dominated in numerical abundance by sternopygids. Comparison of species composition among major watershed indicates that the Negro and Amazon share more species of electric fish with each other than either does with the Orinoco, as would be predicted from the continuity of the first two.},
	keywords = {0329:Ecology, 0472:Zoology, Apteronotidae, Biological sciences, Ecology, Hypopomidae, Rhamphichthyidae, Sternopytgidae, Zoology},
	url = {http://search.proquest.com/docview/304179840?accountid=14270},
	author = {Fernandes, Cristina Cox}
}
