Estrutura funcional e conservação de assembleias de peixes de riachos na Amazônia Brasileira
Carregando...
Arquivos
Data
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Nacional de Pesquisas da Amazônia - INPA
Resumo
All ecosystems on Earth are facing unprecedented levels of human-induced disturbances. Tropical forests, which support enormous diversity of species, currently suffer the most
dramatic landscape changes. These forests are also characterized by elevated proportions of
rare species, which are the first to become extinct under the increasing and cumulative
impacts. Given this scenario, a precise quantification of the biotic responses to environmental
changes has become urgent. Moreover, we need to develop predictive approaches capable of
identifying the consequences of species extinction to the structure of communities and to
ecosystem functioning. Biodiversity should thus be considered in its several facets. Assessing
the diversity and distribution of functional traits within species assemblages (i.e., functional
structure) is a promising perspective to investigate these changes in ecosystems. In this
context, the present study focused on a vulnerable and species-rich group: Amazon stream
fishes. Our main objectives included: 1) determining the mechanistic pathways through which
land use affects the functional structure of stream fish assemblages in the human-modified
mid-eastern Amazon; and 2) investigating the possible consequences of the extinction of rare
species on the functional structure of stream fish assemblages. To achieve the first goal, we
sampled fish in 94 streams, and characterized stream habitat conditions and key landscape
variables, including density of road crossings (i.e., riverscape fragmentation), degree of
deforestation, and agricultural land use intensification. 141 species were functionally
characterized using ecomorphological traits describing feeding, locomotion, and habitat
preferences. We found that multiple drivers operating at different spatial scales influence
stream condition and the functional structure of the fish assemblages. Riparian deforestation
increased submerged vegetation, which reduced the functional evenness of assemblages (i.e.,
domination of a few trait combinations). Fragmentation upstream from sampling sites and
deforestation altered channel morphology and stream bottom, changing the assemblage
functional identity. Fragmentation downstream from sites reduced functional richness,
evenness and divergence, suggesting a reduction in the range of niches filled and a functional
homogenization of local assemblages. To achieve the second goal of the study, we sampled
320 streams along the main tributaries of the Amazon Basin, and functionally characterized
all 395 fish species found in the samples. We then built an integrative measure of species
rarity (i.e., by combining local abundance, geographic range, and habitat breadth) and
assessed the contribution of rare species to complementary facets of assemblage functional
structure using realistic scenarios of species loss. To enhance the generality of our findings,
we applied this framework to other two sets of tropical assemblages: trees from French
Guiana, and birds from the Australian Wet Tropics. We show that rare species have the most
extreme and unique combinations of traits for the three taxonomic groups, and detected
disproportionate impacts of rare species potential extinction on the functional structure of the
assemblages. These results justify the application of the precautionary principle for tropical
biodiversity conservation, despite the expected buffering effects provided by functional
redundancy in such species-rich systems. Overall, we believe that this study gives important
insights to improving the management and conservation of tropical biodiversity.
Descrição
Palavras-chave
Citação
Coleções
Avaliação
Revisão
Suplementado Por
Referenciado Por
Licença Creative Commons
Exceto quando indicado de outra forma, a licença deste item é descrita como Attribution-NonCommercial-NoDerivs 3.0 Brazil