Determinantes da estrutura de comunidades de Trichoptera Kirby, 1813 (Insecta) de riachos de cabeceira em múltiplas escalas espaciais
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2013-05-20
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Universidade Federal de Goiás
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Headwater streams biodiversity is very important to the maintenance of the biological
integrity found in the whole hydrological basin. Therefore, understanding the processes
generating and/or influencing biodiversity in such environments may contribute to
future aquatic integrity monitoring programs and to the strategic planning for both
species and community conservation found within the every stream networks. The main
goals of the current study were to: i) identify landscape and spatial environmental
predictors responsible for the structure of aquatic insects communities (Trichoptera); ii)
identify which hierarchical scale within the hydrologic basins is responsible for the
highest biodiversity variation, what may provide subsidies for future studies and
planned conservation of lotic environments. In order to achieve such goals, we did
different studies with specific objectives directed to (i) measure the contribution of
environmental and spatial variables while determining species richness and composition
within Trichoptera communities, separately considering species with wide and narrow
spatial distribution; (ii) measure the influence of landscape attributes such as vegetation
cover in different spatial scales on species richness and bet diversity, as well on the
different trophic functional groups found within the Trichoptera community; (iii)
evaluate the effects of nested headwater streams community structure embedded within
superior hierarchical levels (e.g. microbasins, subbasins, and the whole catchment), as
well as the effects of the environmental and spatial predictors on alpha, beta and
gamaTrichoptera diversity considering different spatial scales. All studies were
performed with a set of biological data sampled in 48 headwater streams within two
hydrographic basins locate within the state of Goiás, Brazil, with different land use
regimes. Within those streams, local environmental variables (physical-chemical
variables and habtat integrity), landscape attributes (vegetation cover, and land use
classification), and also the biological data regarding the Trichoptera insects were
sampled. In the first study, we observed that compositional changes within the
Trichoptera communities was determined by local processes, especially for genus with
wider distribution, while the communities of those species with narrower distribution
were probably structured by other factors not measured here. This study reinforces that
the use of community deconstruction related to specific species attributes (e.g. spatial
distribution) contributes to a better comprehension of the processes determining the
metacommunities structure. In the second study, we verified that landscape attributes
within the hydrologic basin, such as vegetation quality around the streamlet and
vegetation cover up to 200m from the streamlet, are important predictors to the structure
and functioning of Trichoptera communities. In the third study, results indicate that the
variation in alpha, beta and gama diversities depend on the spatial scale considered and
that the environmental degradation affects distinctly such patterns. We were able to
verify that the structure of Trichoptera communities is determined by environmental
factors, mainly in the local scales, such as water physical-chemical parameters and
vegetation cover. Additionally, we observed that that the spatial scale within which the
diversity is maximized is on catchment scale, reinforcing the need to increase the spatial
scales considered in such studies in order to obtain a higher diversity for the Trichoptera
in headwater streams. Finally, these studies confirm the vulnerability of Trichoptera
communities to the variability on water quality and landscape changes, supporting the
use of these organisms as indicators and reinforcing the need of conservation strategies
which consider the aquatic diversity within each streamlet embedded in hydrologic
basin elsewhere.
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FERREIRA, Juliana Simião. Determinantes da estrutura de comunidades de Trichoptera Kirby, 1813 (Insecta) de riachos de cabeceira em múltiplas escalas espaciais. 2013. 132 f. Tese (Doutorado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2013.