Anais CBFic - Volume 1 - 2018

Sociedade Brasileira de Ficologia - SBFic

Publicado em 26/11/2018

Volume 1 - 2019

Título do Trabalho

INFLUENCE OF WATER VOLUME REDUCTION ON THE PHYTOPLANKTON DYNAMICS IN A SEMI-ARID MAN-MADE LAKE

Autores

VANESSA BECEKR, GUSTAVO G. BRAGA

Modalidade

Resumo

Área Temática

1 BIODIVERSIDADE, FILOGENIA E ECOFISIOLOGIA

Data de Publicação

26/11/2018

País da Publicação

Brasil

Idioma da Publicação

Português

Página do Trabalho

http://sbfic.org.br/anais_show/7

ISSN

Aguardando...

Palavras-Chave

Drylands, Functional Groups, Morphology-based, drought, water level fluctuations

Resumo

Reservoirs and man-made lakes in semi-arid regions are mostly shallow and subjected to wide seasonal water volume variation, as a result of the precipitation irregularity in these regions . Significant reduction on the water level of lakes is influenced by droughts and freshwater demands especially in semi-arid regions, where the stress hydric predominates. A useful way for studying changes in phytoplankton assemblages is grouping organisms based on similarities of their adaptive strategies . Thus, organisms can be grouped in morpho-physiological traits that respond to light availability and nutrient concentration on a similar way. This approach was named trait-based approach and it facilitates the comprehension of the species selection dynamics in the community, because it captures greater variability then taxonomic approaches. Our study highlights that the water volume reduction associated with light limitation and nutrients increase, can trigger phytoplankton overgrowth in a Brazilian semi-arid man-made lake during a drought event. The aim of this study was to investigate phytoplankton dynamics during two different water volume periods as a result of an extended drought in a semi-arid lake. Descriptor species were classified using functional trait approaches. Light and nutrients availability were the main resources that explained the phytoplankton functional groups composition. The phytoplankton dynamic changed from species of meso-eutrophic habitats to adapted organisms of eutrophic and turbid environments during a drought event. Both classifications applied separated samples of low volume period from the high volume period ones, and also evidenced the importance of light availability on phytoplankton assemblage, as these two period showed significant differences in their transparency and phytoplankton composition. During extended droughts the water volume reduction enhances the development of bloom-forming cyanobacteria groups by light limitation.