Non‐native species outperform natives in coastal marine ecosystems subjected to warming and freshening events

Ella Mcknight,Marc Rius,Dan A Smale,Rebecca Spake,Amanda Bates,Fabien Leprieur

doi:10.1111/geb.13318

Abstract

AbstractAimsContemporary climate change and biological invasions are two main drivers of biodiversity redistribution. Interactive effects between these drivers have been reported in a variety of studies, yet results are conflicting. Some studies find that contemporary climate change facilitates the spread and success of non‐native species, especially those with broad physiological tolerances. Other studies conclude that non‐natives are vulnerable to current and future changes in climatic conditions. Given that most studies have focused on terrestrial species, here we contribute to this debate by analysing responses of marine native and non‐native fauna and flora to key climate‐related stressors, namely increased temperature (warming) and decreased salinity (freshening).LocationGlobal.Time period2002–2019.Major taxa studiedMarine benthic macrophytes and invertebrates.MethodsWe conducted a meta‐analysis of experiments investigating the performance (e.g. growth, survival and reproduction) of benthic species in response to warming and freshening.ResultsWe found that non‐native species tended to respond positively to elevated temperature, whereas the performance of native species declined. Similarly, decreased salinity negatively affected the biological processes of native species, but non‐natives showed neutral or negative overall responses to freshening.Main conclusionsWe find evidence that non‐native species outperform natives under a wide variety of warming and freshening conditions. The growth and reproduction of non‐natives are enhanced by warmer temperatures, and thus ocean warming is expected to facilitate future spread and success of non‐native species. Increased freshening along future coastal areas, however, will likely have a negative impact in both native and non‐native species and thus is expected to be a driver of significant change in coastal marine ecosystems. Our comprehensive analysis highlighted the need to expand our understanding of climate change effects beyond warming and specifically, studies focusing on salinity changes.

Highlights

Ecosystems around the globe are increasingly threatened by contemporary climate change and the spread of non-native species (Early et al, 2016)
Climate change drivers are directly responsible for altering species phenology and ecosystem functioning (Smale et al, 2019; Wernberg et al, 2013; Wolkovich & Cleland, 2010)
Minimum adequate model as the one with the lowest Akaike’s information criterion (AIC) value (Burnham & Anderson, 2002)

Summary

| INTRODUCTION

Ecosystems around the globe are increasingly threatened by contemporary climate change and the spread of non-native species (Early et al, 2016). Stephens et al (2019) reported overall negative effects of both temperature and CO2 increases on non-native performance in both marine and freshwater ecosystems. These conflicting results suggest further analysis of the effects of climate change on native and non- native species is needed. We performed a meta-analysis to investigate how two key climate-related stressors – increased temperature (hereafter ‘warming’) and reduced salinity (hereafter ‘freshening’) – influence different biological processes (e.g. growth, survival, reproduction) in both native and non-native coastal marine and brackish species. | 3 species (Diez et al, 2012; Velasco et al, 2018), (c) early life-history stages will be more adversely affected by climate-related stressors than adults, as early life-history stages are often more vulnerable to variability in abiotic factors (Pineda et al, 2012), and (d) non- native plants (i.e. macroalgae or angiosperms) will respond positively to climate-related stressors (in line with Stephens et al, 2019 who found that non-native terrestrial plants benefited from increased climatic variability)

| METHODOLOGY

| DISCUSSION

| CONCLUSIONS