Periphytic algae traits are mainly lognormally distributed in a neotropical floodplain tributary

Abstract

In addition to playing an empirical role in establishing a close characterization of ecological communities, species-abundance distribution enables the comparison of different communities with a compact description of structures. Several models seek proper understanding of this distribution, although currently two are the models more commonly used: log-series and lognormal. Studies on these patterns raise theories seeking an improved understanding. In this context, Hubbell proposes a neutral model (Unified Neutral Theory) as zero-sum multinomial species-abundance distribution model bringing renewed understanding and discussion. Since the neutral theory is expressly related to communities of non-motile organisms, the periphytic algal community represents an excellent group to have patterns and ecological theories investigated. Thereby, the objective of this study is the assessment of periphytic algal community structure supported by the Neutral Theory. Data include samples of petioles from stands of the Eichhornia azurea (Sw.) Kunth aquatic macrophyte (n = 45). We fitted five SAD models to our data (Poisson lognormal, lognormal, log-series, zero-sum multinomial and the geometric series). The non-neutral model (lognormal distribution) fit more satisfactorily. Hence, in the context of our results, we present two conclusions: the periphytic algal community dynamics cannot be regarded as neutral and the structuring did not occur through ecological drift. Our study reveals the relevance of periphytic algal communities as an object of study for ecological theories and the importance of the SAD modeling debate.