Comunidades de macroinvertebrados de riachos ainda apresentam um sinal biogeográfico
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2019-02-21
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Universidade Federal de Goiás
Resumo
Ecosystems can have alternative stable states. In theory, temporal or spatial changes of a key environmental
variable (e.g., phosphorus concentration), after a certain threshold, would cause rapid and abrupt changes in
the state of an ecosystem (e.g. from oligo to eutrophic). The theory also predicts that feedback mechanisms
hinder the return of an ecosystem to its original state, even when the change in the key variable is in the
opposite direction. Detecting changes in ecological regimes is important to identify biogeographic
boundaries and where environmental disturbances are occurring. The general objective of this work is to
identify spatial changes in the state of streams macroinvertebrate communities. To do so, we used a large
dataset covering the entire continental territory of the United States of America. We use a priori
(ecoregions) and a posteriori classifications (based on environmental and anthropogenic variables) to
quantify whether these typologies are representing the structure of macroinvertebrate communities. We
calculated the classification strength considering ecoregions and environmental/anthropogenic variables as
classification factors. We expected that these environmental/anthropogenic variables would have greater
classification strength considering the strong environmental impacts on aquatic ecosystems. However, the
classification strength of ecoregions was much higher than those of environmental/anthropogenic variables.
We also found that areas of abrupt changes in communities are in part coincident with transitional zones
between ecoregions. Therefore, our results indicate that there is still a clear biogeographic sign on
macroinvertebrate communities, despite the strong anthropogenic environmental changes that aquatic
ecosystems have undergone.
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LIBÓRIO, C.H.L. Comunidades de macroinvertebrados de riachos ainda apresentam um sinal biogeográfico. 2018. 49 f. Dissertação (Mestrado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2019.