Vertical and temporal dynamics of cyanobacteria in the Carpina potable water reservoir in northeastern Brazil

Abstract

This study analysed vertical and temporal variations of cyanobacteria in a potable water supply in northeastern Brazil. Samples were collected from four reservoir depths in the four months; September and December 2007; and March and June 2008. The water samples for the determination of nutrients and cyanobacteria were collected using a horizontal van Dorn bottle. The samples were preserved in 4% formaldehyde for taxonomic analysis using an optical microscope, and water aliquots were preserved in acetic Lugol solution for determination of density using an inverted microscope. High water temperatures, alkaline pH, low transparency, high phosphorous content and limited nitrogen content were found throughout the study. Dissolved oxygen stratification occurred throughout the study period whereas temperature stratification occurred in all sampling months, with the exception of June. No significant vertical differences were recorded for turbidity or total and dissolved forms of nutrients. There were high levels of biomass arising from Planktothrix agardhii, Cylindrospermopsis raciborskii, Geitlerinema amphibium and Pseudanabaena catenata. The study demonstrates that, in a tropical eutrophic environment with high temperatures throughout the water column, perennial multi-species cyanobacterial blooms, formed by species capable of regulating their position in the water column (those that have gas vesicles for buoyancy), are dominant in the photic and aphotic strata.

Cyanobacteria, microcystins and cylindrospermopsin in public drinking supply reservoirs of Brazil

“…Costa et al (2006), Bittencourt-Oliveira et al (2011a, 2012b, Moura et al (2011), andLira et al (2011) reported multi-species blooms of cyanobacteria constituted mostly by the genera Planktothrix and Cylindrospermopsis, with possible alternation of predominance according to the climate conditions.…”

Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors

“…Planktothrix agardhii, a possible toxin producing species, is currently known to form blooms in Indonesia and Brazil (Akcaalan et al, 2006;Moura et al, 2011). P. agardhii blooms in Carpina Reservoir, Brazil were found to co-dominate with C. raciborskii.…”

Toxic Cyanobacteria in Four Brazilian Water Supply Reservoirs

“…Its drainage basin receives part of the domestic sewage from the city of Garanhuns, PE, which has 150,000 inhabitants, approximately [17]. With a maximum volume of 2.7 million m 3 , Carpina reservoir is important for irrigation and fishery activities, in addition to its use for public water supply [18].…”