Phytoplankton, Trophic State and Ecological Potential in reservoirs in the State of São Paulo, Brazil

Eduardo Henrique Costa Rodrigues,Marcelo Luiz Martins Pompêo,Leila Dos Santos Machado,Aline Martins Vicentin,Viviane Moschini Carlos

doi:10.4136/ambi-agua.2428

Abstract

This study evaluated the ecological potential of reservoirs in the Brazilian state of São Paulo, having phytoplankton as a biological quality element. Integrated water column sampling was carried out in the dam, and in the intermediate and fluvial zones of the Igaratá, Atibainha, Paiva Castro, Rio Grande, Itupararanga, Broa, Barra Bonita, Guarapiranga and Salto Grande reservoirs in July 2015. Physico-chemical and biological parameters were analyzed in all environments. The phytoplankton was analyzed under an inverted microscope, and measurements of density, diversity, equitability and dominance were determined. The data was ordered using PCA and CCA analysis. The ecological potential of the reservoirs was determined through the evenness index. The electrical conductivity, nitrate, nitrite and orthophosphate were higher in the more eutrophic reservoirs: Salto Grande, Barra Bonita, Guarapiranga and Rio Grande. A trophic gradient was observed among the sampling points, suggesting a conservation spectrum. There was dominance of cyanobacteria in the eutrophic reservoirs associated with low diversity and high dominance. The total density was correlated with TP, TN, and pH. A divergent relationship between the trophic state index and the evenness index was observed. The Atibainha, Itupararanga, Broa, Barra Bonita and Salto Grande reservoirs were classified as water bodies of very poor ecological quality (Bad). The evenness index seems to be a good alternative to the biomonitoring of the studied reservoirs.

Highlights

In recent years the water quality of reservoirs has been significantly affected by human activities, increasing the frequency of impacts related to pollution and contamination
The low diversity values observed in Broa, Barra Bonita, Itupararanga and Salto Grande reservoirs may be directly related to the dominance of Microcystis aeruginosa
Our results have suggested the formation of monospecific blooms of Microcystis aeruginosa in Broa, Barra Bonita and Salto Grande reservoirs

Summary

Introduction

In recent years the water quality of reservoirs has been significantly affected by human activities, increasing the frequency of impacts related to pollution and contamination. These impacts lead to eutrophication, resulting in loss of water quality and permanent change in the trophic condition of these environments, making them eutrophic. Phytoplankton is among the most-affected organisms, undergoing changes in their dynamics and ecological structure. These organisms represent an important element of aquatic ecosystems, playing a central role in their structure and functioning. Phytoplankton responds rapidly to any change in the environmental characteristics of an ecosystem, mainly to nutrient concentrations, and has been widely used in water monitoring studies (Vicentin et al, 2018; Batista and Fonseca, 2018; Moschini-Carlos et al, 2017; Tucci et al, 2009)

Methods

Results

Conclusion