Cumulative effects of multiple stressors: An invasive oyster and nutrient enrichment reduce subsequent invasive barnacle recruitment

Abstract

16Studies identifying interactions between biological invasions and other stressors have 17 generally focussed on quantifying their cumulative effects on mature species assemblages. In 18 benthic systems, however, early life history processes are key determinants of assemblage 19 structure and functioning. This study tested whether the presence of an invasive species 20 affected early life history processes of two common barnacle species and whether this was 21 affected by a second common stressor, nutrient enrichment. The results of a field experiment 22 identified and characterised the effects of an invasive oyster, Crassostrea gigas, on the early 23 life history processes of the two barnacle species under ambient and enriched nutrient 24 conditions. In the presence C. gigas, the invasive barnacle Austrominius modestus, had a 25 lower recruitment rate, however, there was no effect of the presence of C. gigas on native 26 barnacle, Semibalanus balanoides, recruitment. Nutrient enrichment also reduced the 27 recruitment rate of A. modestus, however, there was no evidence of synergistic or 28 antagonistic interactions between these stressors, indicating their cumulative effects were 29 additive. There was no effect of nutrient enrichment on native barnacle recruitment. Our 30 results show that the presence of an invasive oyster and nutrient enrichment altered the 31 recruitment of another non-native benthic species. These findings emphasise the importance 32 of considering early life history processes when assessing effects of multiple stressors on 33 communities. 34 3

Combined effects of warming and nutrients on marine communities are moderated by predators and vary across functional groups

“…When ecological responses to environmental drivers interact—that is, when their combined effects are either significantly greater (synergistic; Sala & Knowlton, ) or less than (antagonistic; Crain et al, ) the sum of their individual effects—predicting their cumulative impacts remains a significant challenge. We found that effects of predators and our experimental perturbations on univariate ecosystem functions—community metabolism, the biomass of algae and grazers, and abundance of meso‐invertebrates—were generally additive (i.e., equal to the sum of the individual effects; Vye, Emmerson, Dick, & O'Connor, ). This suggests that interactions between multiple stressors may not be a pervasive phenomenon in marine systems (Halpern et al, ).…”

Multiple Driver Impacts on Rocky Intertidal Systems: The Need for an Integrated Approach

“…Furthermore, the difference in stressor impacts for various life forms demands research with regard to multiple anthropogenic drivers across the range of life history stages (Vye et al, 2017). The early life stages of intertidal species are crucial for the structure and function of adult populations on rocky shores and should be taken into consideration when investigating the effects of anthropogenic drivers (Connell, 1985).…”

The ecological impacts of multiple environmental stressors on coastal biofilm bacteria

“…Environmental stressors such as warming, nutrient enrichment, and harvesting of top predators are not present in isolation and often combine in surprising ways that cannot be predicted from their individual impacts (Crain et al, 2008;Vye et al, 2015Vye et al, , 2017.…”