O papel de mudanças hidrológicas de ordem sazonal e climática na estrutura da assembleia e história de vida de peixes na confluência dos rios Negro e Amazonas
Flow varability in space and time is widely regarded as a master variable that shapes the ecological characteristics of rivers and streams. Recently combined effects of climate change and deforestation have changed precipitation patterns in the Amazon, which in turn have changed the magnitude and...
| Autor principal: | Röpke, Cristhiana Paula |
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| Grau: | Tese |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/11489 http://lattes.cnpq.br/5813620045238575 |
| Resumo: |
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Flow varability in space and time is widely regarded as a master variable that shapes the ecological
characteristics of rivers and streams. Recently combined effects of climate change and
deforestation have changed precipitation patterns in the Amazon, which in turn have changed the
magnitude and timing of annual flow cycle. Effects of these changes on freshwater ecology and
biology are poorly known. Here we investigated the effect of seasonal and interannual hydrological
dinamics on assemblage structure and fish reproductive investment, emphasising the role of
extreme events. Analysis of long-term data for hydrology and fish surveys in a floodplain lake
near the confluence of Amazon and Negro rivers reveals that: i) seasonal connectivity with two
large rivers plays important role on seasonal species turnover and populational recolonization.
Temporal � diversity was high in the lake and the assemblage was dominated by seasonally
transient species. Relatively large species known to feed on resources within the floodplain were
captured almost exclusively during the flood period. During the dry season, the assemblage was
dominated by fishes adapted to harsh conditions of high temperature and low dissolved oxygen
concentrations; ii) analysis of long-term data set showed a significant and concordant changes in
hydrology and assemblage structure. Major shifts coincided with an intense drought in 2005,
followed by years with annual flood pulses of higher magnitude and earlier dry season onset. After
2005, the fish assemblage assumed alternative and persistent taxonomic and functional
compositions indicative of a regime shift in response to an external driver; iii) the analysis of
effects of annual hydrological condition on reproduction shows that extreme events and the
interaction of extreme events and body condition affected female fecundity negatively. Females
of Acestrorhynchus falcirostris, a piscivorous species, reduced the fecundity when had poor body
condition in year of intense flood. Advanced, long and intense dry seasons had negative effect on
Psetrogaster rutiloides fecundity and interacted with body condition on Triportheus angulatus
fecundity. Mean oocyte size was more affected by environmental condition, as high population
density and hydrological situation and its interaction with phenotype than only by individual’s
phenotype (body size and body condition). Population density had a positive effect on the mean
oocyte size in all studied species. The combination of these results suggests that biodiversity
conservation and inland fisheries management in the Amazon will need to account for recent
climatic and hydrologic changes that have the potential to induce ecological regime shifts and
population dynamics. |