Cyanobacteria in the aquatic ecosystem of the environmental protection area (EPA) of Curiaú River, Amapá State, Amazon Region, Brazil

Abstract

The aim of the current study is to feature the composition, frequency and richness of cyanobacteria species and their spatial-temporal distribution patterns in Curiaú River. Quarterly collections were carried out at three sampling sites, from June 2016 to October 2017. Phytoplankton and periphyton samples were collected and fixed with Transeau’s solution to be identified under optical microscope. Data were statistically treated through descriptive, variance and cluster analyses; significance level was set at p<0.05. In total, 17 taxa were identified and grouped into four (4) taxonomic orders, namely: Chroococcales, Nostocales, Synechococcales and, most prevalently, Oscillatoriales. Genera Kamptonema (67%) and Phormidium (44%) were the most frequent taxa. Cyanobacteria richness has shown significant variations (p<0.05) among sampling sites. This pattern was not observed for seasonal fluctuations (p> 0.05). These data also represent pioneering information about cyanobacteria biodiversity in Amapá State.

Composition, frequency and seasonal distribution of periphytic microalgae in stretches of the Curiaú River, Amapá, Eastern Amazon

“…This can reduce water quality with the release of toxins (e.g., microcystin), causing adverse impacts on aquatic ecosystems and human health with economic and ecological consequences [37]. Therefore, greater attention should be paid to the constant monitoring of water from the Curiaú River, which is used for balneability and irrigation in agriculture [18].…”

“…The Curiaú River APA is situated 8 km 2 north of the city of Macapá, in the State of Amapá, Brazil, with a total of 216.76 km 2 , with demarcated boundaries between the Campina Grande community (north), BR-156 Highway (west), Macapá city (south) and the Amazon River (east) [16,17]. The local scenery presents numerous landscapes, with a variety of fauna, flora, and associated microbiota [18] The Curiaú river basin (Figure 1) is interconnected to permanent and temporary lakes influenced by tidal regimes, characteristic of the Amazon region. It presents two distinct seasonal periods: a) dry, comprising the months of July to December; b) rainy, comprising the months of January to June [19].…”

“…It presents two distinct seasonal periods: a) dry, comprising the months of July to December; b) rainy, comprising the months of January to June [19]. It is mainly used for recreation, plantation irrigation, artisanal fishing, and river routes [18]. Studies indicate that water from the Curiaú River presents acid pH, low electrical conductivity, and dissolved oxygen concentration between 4 and 7 mg/L, with transparency of ± 100 cm [20,21]…”