Phytoplankton dynamics in a drinking water catchment zone at the Amazon River mouth

Natalina Borges Da Silva,Luís Roberto Takiyama,Luis Mauricio Abdon Da Silva,Elane Domênica Cunha De Oliveira,Mariano Araújo Bernardino Rocha

doi:10.1590/0102-33062020abb0476

Abstract

Phytoplankton is formed by photosynthesizing microorganisms that act as primary producers in distinct water bodies. These include microalgae and cyanobacteria. It is essential to know the phytoplankton in water catchment areas intended for drinking water treatment once their excessive density may result in problems, such as taste and odor in the water, toxin production, filter clogging, and other damages. This study investigated the phytoplankton dynamics and the environmental factors that may influence phytoplankton density in the drinking water catchment zone of Macapá, a city located on the Amazon River mouth. The sampling was carried out monthly from April/2015 to March/2016. The study reports the first detailed information on the phytoplankton in the study area since previously published studies regarded only cyanobacteria. The species Limnothrix planctonica and Aulacoseira granulata may substantially influence the water treatment due to their great abundance in the study area, especially in July and November, when their density peaks occur, respectively. Nevertheless, Aulacoseira granulata is the primary constituent of the phytoplankton biovolume. This study provides biological and sanitary information to guide public administration towards improving the quality and safety of water supply services, and also to increase the biodiversity knowledge of Amazonian phytoplankton.

Highlights

Phytoplankton comprises photosynthetic microorganisms-microalgae and cyanobacteria-adapted to live partly or continuously in open water (Chorus & Bartram 1999; Reynolds 2006). These organisms are responsible for the oxygenation of aquatic ecosystems, where they act as the primary producer of organic carbon (Reynolds 2006)
The purpose of this study is to investigate the phytoplankton composition, density, and biovolume, and the environmental factors that may have an influence on phytoplankton density in the drinking water catchment zone of Macapá
The samples were collected in the city of Macapá, at the Company of Water Supply and Sewage of Amapá (CAESA), at the raw water intake point, which is situated approximately 500 meters from the Amazon River bank (Fig. 1), nearby the city downtown

Summary

Introduction

Phytoplankton comprises photosynthetic microorganisms-microalgae and cyanobacteria-adapted to live partly or continuously in open water (Chorus & Bartram 1999; Reynolds 2006) These organisms are responsible for the oxygenation of aquatic ecosystems, where they act as the primary producer of organic carbon (Reynolds 2006). In the case of the production of taste and odor compounds, some of the principal causes that make difficult the source-tracking of these compounds include species misidentification (Watson & Jüttner 2019) Because of these issues, it is essential to know the phytoplankton composition and density to prevent or quickly solve future trouble related to water treatment concerns

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