Phytoplankton diversity (alpha, beta, and gamma) from the Araguaia River tropical floodplain lakes (central Brazil)

Abstract

Alpha, beta and gamma are three components of species diversity. Knowing these attributes in floodplain lake phytoplankton communities is vital when selecting conservation areas. Species diversity is commonly used with other taxonomic groups, but rarely with phytoplankton. We compared the number of phytoplankton species (alpha diversity) from 21 Middle Araguaia River floodplain lakes in the 2000 and 2001 rainy and dry seasons. From these samples we estimated complete survey species richness (gamma diversity), quantified differences in species composition between lakes (beta diversity) and assessed the influence of abiotic variables on beta diversity. We recorded a total of 577 taxa. The Sjack1 estimator indicated that 62.31% of taxa were sampled in the 2000 rainy and 67.65% dry seasons, and 68.36% in the 2001 rainy and 73.5% dry seasons. In almost all seasons, alpha diversity negatively correlated with latitude. Beta diversity (b-1) was higher in high water periods, especially in 2000. This may have been caused by isolated heavy rainfall, which would have increased environmental heterogeneity and raised beta diversity. DCA showed differences in phytoplankton composition between rainy and dry seasons in 2000 and 2001, reflecting the influence of flood pulses on phytoplankton composition. The Mantel test indicated spatial distribution patterns where geographically more distant lakes had less-similar phytoplankton communities.

Phytoplankton diversity in the Upper Paraná River floodplain during two years of drought (2000 and 2001)

“…The values for the diversity estimators used here indicate that the obtained samples were sufficient and representative since percentages were equal or greater than 80%. These results were similar to those for the Araguaia River floodplain (Nabout et al, 2007).…”

“…Only Nabout et al (2007) focused exclusively on phytoplankton diversity. Similarly, the study presented here analysed the phytoplankton diversity of the Upper Paraná River floodplain.…”

Alpha and beta diversity of phytoplankton in two subtropical eutrophic streams in southern Brazil

“…The species richness of each sampling site (alphadiversity) was determined from the number of species collected throughout the entire study period, taking into consideration data from qualitative analysis, and was estimated by first and second order jackknife indexes (Nabout et al 2007) with StimateS (Colwell 2006). Occurrence frequencies were categorized as: constant for species found in more than 50% of the collections; common when found between 25% and 50% of the collections; and accidental or rare species when found in less than 25% of the collections (Lobo & Leighton 1986).…”

“…Anthropogenic activities (disposal of organic wastes and removal of riparian vegetation) may cause significant changes to phytoplankton communities (Leland & Porter 2000;Lewis et al 2001;Munn et al 2002). In fact, species richness may be the simplest method to assess and quantify the complexity of a given environment (Nabout et al 2007). Since it is coupled to taxonomic composition, species richness provides a measure of the main components of biological diversity for characterizing an ecosystem and, thus, is important for defining preservation strategies (Nogueira et al 2008).…”

“…Of these, the studies of Huszar et al (1990), Nabout et al (2007), Nogueira et al (2008), Nogueira et al (2010) and Pires (2014) should be highlighted, although these studies only evaluated alpha-and beta-diversity in lentic environments.…”