Responses of the phytoplankton functional structure to the spatial and temporal heterogeneity in a large subtropical shallow lake

Luciane Oliveira Crossetti,Lacina Maria Freitas-Teixeira,Juliana Elisa Bohnenberger,Uwe Horst Schulz,David Da Motta-Marques,Lúcia Ribeiro Rodrigues

doi:10.1590/s2179-975x7217

Abstract

Abstract Aim Studies on biological communities that take into account only the species composition and abundances (or biomass) and their relative contributions, most of the time, do not reflect their ecological functions, especially considering the wide spatial and temporal variation of large shallow lakes. This paper aimed at evaluating the influence of environmental spatial and temporal heterogeneity on the functional structure of phytoplankton in a subtropical large shallow lake. Methods Seasonal samplings were carried out in 2010 and 2011, in 19 sampling sites distributed along the entire length (90 km) and width (3-10 km) of Lake Mangueira, a large (820 km2 ) and shallow lake (zmean = 2.6 m), comprising the littoral and pelagic zones of the north, central and southern regions. Abiotic variables and phytoplankton functional traits (volume, maximum linear dimension, life forms) and functional groups were analyzed as measures of functional structure. Results The results showed that there was no spatial organization of phytoplankton functional traits during the study. Colonial non-flagellated organisms, organisms with cellular volume between 103 and 104 μm3 and greater than 104 μm3, and with maximum linear dimension between 21 and 50 μm prevailed in all zones and regions. Phytoplankton functional groups and traits responded to resource variation, especially increasing their variety and contribution during spring and summer periods. Conclusions The functional structure of the phytoplankton community in Lake Mangueira, here accessed by functional traits and RFGs, was more conditioned by its environmental temporal variability rather than by the spatial variation, indicating that the resources and life conditions seasonal variation strongly influence the phytoplankton in this ecosystem.

Highlights

Functional-based approaches are widely used in ecology (Litchman & Klausmeier, 2008) and, once applied in community ecology, have led to considerable progress in understanding the effects of environmental filters on species organization (Jung et al, 2010)
Abiotic variables and phytoplankton functional traits and functional groups were analyzed as measures of functional structure
The results showed that there was no spatial organization of phytoplankton functional traits during the study

Summary

Introduction

Functional-based approaches are widely used in ecology (Litchman & Klausmeier, 2008) and, once applied in community ecology, have led to considerable progress in understanding the effects of environmental filters on species organization (Jung et al, 2010). They are based on functional traits which may be defined as any morphological, physiological or phenological feature, which impacts fitness indirectly via its effects on growth, reproduction and survival (Violle et al, 2007). Among the most used approaches, Reynolds’ functional grouping system (Reynolds et al, 2002), recently proposed to be named as Reynolds Functional Groups - RFG (Kruk et al, 2017), is one of the most accepted and used (Padisák et al, 2009), and presents advantages over traditional phylogenetic classifications, since it groups organisms based on their survival strategies and their adaptations to environmental conditions (Salmaso & Padisák, 2007)

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Conclusion