Coupling environment and physiology to predict effects of climate change on the taxonomic and functional diversity of fish assemblages in the Murray-Darling Basin, Australia.

Fernanda A S Cassemiro,Thiago F Rangel,Dean Gilligan,Angelo Antonio Agostinho,Nick Bond,Dayani Bailly,Mark J Kennard,Edivando Vitor Do Couto,Anielly Galego De Oliveira,Daniel De Paiva Silva

doi:10.1371/journal.pone.0225128

Abstract

This study uses species distribution modeling and physiological and functional traits to predict the impacts of climate change on native freshwater fish in the Murray-Darling Basin, Australia. We modelled future changes in taxonomic and functional diversity in 2050 and 2080 for two scenarios of carbon emissions, identifying areas of great interest for conservation. Climatic-environmental variables were used to model the range of 23 species of native fish under each scenario. The consensus model, followed by the physiological filter of lethal temperature was retained for interpretation. Our study predicts a severe negative impact of climate change on both taxonomic and functional components of ichthyofauna of the Murray-Darling Basin. There was a predicted marked contraction of species ranges under both scenarios. The predictions showed loss of climatically suitable areas, species and functional characters. There was a decrease in areas with high values of functional richness, dispersion and uniqueness. Some traits are predicted to be extirpated, especially in the most pessimistic scenario. The climatic refuges for fish fauna are predicted to be in the southern portion of the basin, in the upper Murray catchment. Incorporating future predictions about the distribution of ichthyofauna in conservation management planning will enhance resilience to climate change.

Highlights

Climate change is considered one of the greatest threats to global biodiversity [1,2]
Considering that climate is a fundamental factor determining the distribution of organisms at large spatial scales (reflecting the Grinnellian component of the ecological niche [27], and that tolerance limits determine whether the species are able to withstand the conditions imposed by an ever-changing environment, this study aimed to evaluate the effects of climate change on the distribution of native freshwater fish of the Murray-Darling Basin (MDB) using SDM’s combined with a physiological trait
Species richness predictions derived from the consensus model (CONS truncated by upper thermal tolerance limits of the species) identify the upper Murray River region as the richest in the basin (Fig 2), emphasizing the high current climatic-environmental diversity within these drainages, and the suitability of this region for the ichthyofauna

Summary

Introduction

Climate change is considered one of the greatest threats to global biodiversity [1,2]. Impacts include rising air and water temperatures, sea level and greenhouse gases, major changes in regional rainfall and runoff patterns, and increases in the occurrence and severity of extremes events [3,4]. These shifts are expected to impact on the distribution, composition and phenology of species [1,5]. Climate-driven changes in species distributions will have impacts on local community dynamics and diversity, including functional diversity (the biodiversity component related to ecological functions and services played by the species) [9], since the pattern in the distributions of functional traits (species morphological, structural and behavioural characteristics) are likely to change. Because functional traits can influence species performance (or fitness; [10]), the loss of functionally important species can modify ecosystem structure, function and resilience [11,12]

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Conclusion