Abstract

The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity–stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems.

Highlights

  • A high level of biodiversity loss is occurring due to global climate change and human activities [1].The rapid loss of biodiversity has generated great concerns about the influence of diversity on important indicators of ecosystem function, such as productivity and stability [1,2,3,4]

  • There was no significant difference of pH among the four scenarios (one way analysis of variance (ANOVA): F(3, 60) = 2.07, p = 0.113)

  • Here,we weshowed showedthat that phytoplankton phytoplankton diversity diversity effects effects on on both both community biomass and were influenced by nutrients, and varied gradually from positive community biomass and resource use efficiency (RUE) were influenced by nutrients, and varied gradually from positive to to negative along the nutrient gradients

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Summary

Introduction

The rapid loss of biodiversity has generated great concerns about the influence of diversity on important indicators of ecosystem function, such as productivity and stability [1,2,3,4]. Aquatic ecosystems are vulnerable and the loss of biodiversity may cause catastrophic consequences such as algae blooms or secondary extinctions [5,6]. Studies on the relationship between phytoplankton diversity and ecosystem functioning are essential to develop appropriate conservation strategies in aquatic ecosystems [5,7]. Studies related to the biodiversity effects on ecosystem functioning were mainly focused on terrestrial ecosystems, grasslands [8,9]. A positive relationship between diversity and productivity was observed and supported by many laboratory and field

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