Association between biotic and abiotic parameters and the occurrence of cyanobacteria in a Brazilian reservoir

Abstract

The water reservoir of Vargem das Flores, Brazil, has been subject to eutrophication problems. The occurrence of cyanobacterial blooms in this water body has raised concerns regarding the presence of toxic metabolites. In order to understand the factors that promote the proliferation and distribution of cyanobacteria in the reservoir, physicochemical parameters, species composition, and toxicity of the reservoir water column were analyzed at monthly intervals over a 3-year period (2004-2007) using a range of analytical techniques. The results showed that cyanobacteria were absent in the dry period, returning after the onset of stratification. A succession pattern was observed within this group. The Aphanocapsa genus was dominant in the last rainy period of the study (October 2006 to March 2007). However toxicity was only detected when the genera Microcystis and Sphaerocavum were present (October 2005). The principal components analysis showed negative correlation between cyanobacteria and orthophosphate. The change of dominant cyanobacteria along the 3 years of study and the final prevalence of nontoxic genera in the reservoir is an evidence of water quality improvement in response to the management techniques implemented in the reservoir basin.

Identification of Cyanobacteria in a Eutrophic Coastal Lagoon on the Southern Baltic Coast

“…The dominance of picocyanobacterial species is reported for other lagoons, e.g., Patos Lagoon, Brazil or Florida Bay, United States (Phlips et al, 1999), Chesapeake Bay, United States (Wang and Chen, 2004; Chen et al, 2006) and Laguna Chascomús, Argentina (Iachetti and Llames, 2015) ( Table 1 ). Similar phytoplankton communities are also found in freshwater lakes (e.g., Lake Santa Olalla, Spain (López-Archilla et al, 2004), Lake Baikal, Russia (Belykh et al, 2006), lakes in southern Sweden (Komárková-Legnerová and Cronberg, 1994), Guarapiranga Reservoir, Brazil (Santos et al, 2015), Vargem das Flores Reservoir, Brazil (Gomes et al, 2012), reservoirs along the Iguaçu River, Brazil (Silva et al, 2005) and in the Mount Cameroon region, Cameroon (Oben and Oben, 2006). Shallowness and a eutrophic state are common features of all these waters.…”

The necessity of management in a lake of the Atlantic Forest biodiversity hotspot: nitrogen levels connected to a persistent bloom of Cylindrospermopsis raciborskii

“…Cyanobacteria are often controlled by temperature, producing blooms in the warmest seasons (Bouvy et al 1999;McGregor & Fabbro 2000; The necessity of management in a lake of the Atlantic Forest biodiversity hotspot: nitrogen levels connected to a persistent bloom of Cylindrospermopsis raciborskii & Giani 2001;Gomes et al 2012). The relatively stable temperature in the optimum range (above 22°C) for cyanobacteria (Soares et al 2013;Chen 2015) must have contributed to the constant C. raciborskii dominance, as noted by Figueredo & Giani (2009) in Lagoa Santa, Brazil.…”

Monitoring studies should consider temporal variability to reveal relations between cyanobacterial abundance and environmental variables

“…Absolute values of both environmental variables and cyanobacterial abundance vary over time in most ecosystems , Gomes et al 2012, highlighting the importance of temporally structured ecological processes. However, it is unclear how environmental determinism on cyanobacteria varies.…”

“…Such evidence for the causes of cyanobacterial growth has been identified mainly in experiments (Paerl et al 1985, Coles and Jones 2000, Aubriot and Bonilla 2012. Observational studies have also tried to relate environmental variables and cyanobacteria densities (Havens et al 1998, Burford et al 2007, Gomes et al 2012. However, relationships between cyanobacteria densities or cyanotoxin concentrations with the variables described above are not always evident (Wicks and Thiel 1990, Quesada and Fernández-Valiente 1996, Vezie et al 1998.…”