Changes in ecosystem functions generated by fish populations after the introduction of a non-native predator (Cichla kelberi) (Perciformes: Cichlidae)

David J Hoeinghaus,Rodrigo Fernandes,Angelo A Agostinho,Zacchaeus G Compson,Luiza Bangoim Leal,Fernando M Pelicice

doi:10.1590/1982-0224-2021-0041

Abstract

Abstract The introduction of non-native predators is a matter of great concern, but their impacts on ecosystem functions remain poorly understood. We investigated how changes in fish diversity following the invasion of Cichla kelberi affected ecosystem functions generated by fish populations. Fish assemblages were sampled in macrophyte patches in a Neotropical impoundment over a 5-year period, before and after the introduction of the predator. We assigned seven ecosystem functions (26 trait-states) to each fish species, and examined how these functions behaved after the invasion. We collected 577 fish belonging to 25 species. Species richness, fish biomass and main species declined significantly over periods. The biomass of ecosystem functions changed significantly over time, and most trait-states declined. Few trait-states were lost, but all functions had at least one trait-state reduced by more than 85%. A null model analysis showed that changes in functions were not driven by species identities, while species richness correlated positively with total biomass and with most functions, suggesting that the loss of taxa and biomass drove observed changes in ecosystem functions. Our study provided evidence that community disassembly associated with the invasion of C. kelberi translated to the decline of several ecosystem functions, affecting energy mobilization and transference.

Highlights

Ecosystem functions are ecological, biological and physical/chemical processes that maintain ecosystem functioning (Naeem et al, 1999; Hooper et al, 2005; Naeem et al, 2012)
The present study investigated how the invasion of Cichla kelberi Kullander & Ferreira, 2006 affected ecosystem functions generated by fish assemblages associated with aquatic macrophytes in a tropical reservoir (Rosana Reservoir, Paranapanema River, Brazil)
Studies have reported a myriad of consequences that emerge from fish invasions (e.g., Leprieur et al, 2008; Olden et al, 2018; Toussaint et al, 2018; Bezerra et al, 2019), but the effects on ecosystem functions remain poorly investigated

Summary

Introduction

Biological and physical/chemical processes that maintain ecosystem functioning (Naeem et al, 1999; Hooper et al, 2005; Naeem et al, 2012) They include, for example, energy transfer, pollination, decomposition, primary production, biomass accumulation, population control, nutrient cycling, and climate regulation, among many others. Much recent research effort has been devoted to understanding how biodiversity, and especially biodiversity loss, affects ecosystem functioning. Results can vary depending on ecological context and spatial and temporal scales, in general, there is compelling evidence that species and functional diversity of local communities strongly affect ecosystem functioning (Cadotte et al, 2011; Cardinale et al, 2012; Hooper et al, 2012; Naeem et al, 2012; Balvanera et al, 2014; Tilman et al, 2014; Daam et al, 2019).

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