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Universidade Federal Rural de Pernambuco (URFPE) 2021

Florações Algais no estado de Pernambuco : causas, consequências e controle

AMORIM, Cihelio Alves

Titre : Florações Algais no estado de Pernambuco : causas, consequências e controle

Auteur : AMORIM, Cihelio Alves

Université de soutenance : Universidade Federal Rural de Pernambuco (URFPE)

Grade : Doutorado em Biodiversidade 2021

Résumé partiel
This thesis aims to understand the regulatory factors of algal blooms in tropical reservoirs, considering the morphofunctional characteristics of the species, in addition to defining the causes and consequences on phytoplankton and zooplankton and proposing strategies to control these blooms. This study was performed in 10 public water supply reservoirs with different climatic and eutrophication conditions in Pernambuco state, Brazil. Samples were collected quarterly for one year in each environment (n = 42) to understand the role of limnological, climatic, and biotic variables on the intensity of blooms and their effects on planktonic communities. All reservoirs showed cyanobacterial blooms classified as level 1 (biomass >0.2 and <10 mg L-1) or level 2 (biomass >10 mg L-1) of World Health Organization alert. With that, data were distributed in five articles. The first article aimed to evaluate the influence of physicochemical variables and trophic interactions with zooplankton on cyanobacterial blooms. The partial canonical correspondence analysis revealed that blooms were driven mainly by chemical variables, followed by physical and zooplankton variables. To achieve the objective, a structural equation model was built, which demonstrated that the cyanobacterial biomass was mainly favored by the total dissolved phosphorus and the presence of cyclopoid copepods. On the other hand, solar radiation, air temperature, mixing zone, salinity, calanoid copepods, and cladocerans explained the biomass of cyanobacterial morphotypes. In the second article, the objective was to understand the dynamics of the functional groups of Reynolds phytoplankton to establish the relationships between the driving factors of its biomass and distribution. Habitat templates and assembly rules for 20 functional groups were created, integrating data on group preferences and tolerances to 10 environmental gradients. Additive generalized models revealed that salinity, trophic state, reactive soluble phosphorus, water transparency, relative biomass of herbivorous zooplankton, and dissolved inorganic nitrogen were the main predictors of functional group biomass.

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Page publiée le 29 décembre 2022