Aims: Contemporary climate change and biological invasions are two main drivers of biodiversity redistribution. Interactive effects between these drivers have been reported in a number of study systems, yet results are conflicting. Some studies find that future 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 coastal native and non-native fauna and flora to key climate-related stressors namely increased temperature (warming) and decreased salinity (freshening).

Location: Global.

Time period: 2002 – 2019.

Major taxa studied: Marine benthic macrophytes and invertebrates.

Methods: We conducted a meta-analysis of results from experiments investigating the performance (e.g., growth, survival and reproduction) of sessile and sedentary species from benthic marine communities to warming and freshening.

Results: We found evidence of positive responses to elevated temperature across a range of biological processes on non-native species, whereas the performance of native species declined. Similarly, decreased salinity negatively affected the biological processes of native species, but non-natives showed no positive or negative overall response to freshening.

Main conclusions: Our study showed 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, however, will likely have a negative impact in the future in both native and non-native species and thus is expected to be a driver of significant change in coastal marine ecosystems. Our comprehensive literature search revealed the need of more studies focusing on salinity changes and highlighted the need to expand our understanding of climate change drivers beyond warming.

Data were extracted from peer-reviewed published literature from studies that measured biological responses of native and non-native species to experimentally controlled changes in warming (temperature) and freshening (salinity).