A functional deconstructive approach to mixotrophic phytoplankton responds better to local, regional and biogeographic predictors than species

Abstract

The use of deconstructive approaches, such as functional classification models, can be an importanttool for understanding aquatic systems. This study aimed to evaluate the distribution and community structureof mixotrophicflagellates in lakes of four large Brazilianfloodplain systems, those of Amazon River, AraguaiaRiver, Pantanal and upper Paran a River, in contrasting hydrological periods. A partial redundancy analysis(pRDA) was used to estimate the relative roles of environmental, spatial and biogeographic factors on both theentire community and a deconstructive approach using Reynolds’mixotrophicflagellate functional groups(RFGs). High environmental variability was found between the rainy and dry periods, mostly for the Amazonfloodplain system. We identified 135 taxa and seven RFGs of mixotrophicflagellates:E,Lo,Q,W1,W2,WsandY.APERMANOVAevidenced that biomass of mixotrophicflagellate RFGs reflected differences amongflood-plains and between hydrological periods. Our results showed that the use of RFGs better summarises the mixo-trophic phytoplankton metacommunity structure when compared to the use of the entire community. ThepRDA showed that explanatory matrices explained up to 37% of variation in the community. Environmental,spatial and biogeographic factors were important to explain the structure of the mixotrophicflagellates; however,the importance of the different components seemed to depend on the hydrological period and the traits of each RFG.