Biological invasions, nutrient enrichment and ocean warming are known to threaten biodiversity and ecosystem functioning. The independent effects of these ecological stressors are well studied, however, we lack understanding of their cumulative effects, which may be additive, antagonistic or synergistic. For example, the impacts of biological invasions are often determined by environmental context, which suggests that the effects of invasive species may vary with other stressors such as pollution or climate change. This study examined the effects of an invasive seaweed (Sargassum muticum) on the structure and functioning of a synthetic macroalgal assemblage and tested explicitly whether these effects varied with nutrient enrichment and ocean warming. Overall, the presence of S. muticum increased assemblage productivity rates and warming altered algal assemblage structure, which was characterised by a decrease in kelp and an increase in ephemeral green algae. The effects of S. muticum on total algal biomass accumulation, however, varied with nutrient enrichment and warming, producing antagonistic cumulative effects on total algal biomass accumulation. These findings show that the nature of stressor interactions may vary with stressor intensity and among response variables, which leads to less predictable consequences for the structure and functioning of communities.
Aim Understanding patterns in the abundance of species across thermal ranges can give useful insights into the potential impacts of climate change. The abundant‐centre hypothesis suggests that species will reach peak abundance at the centre of their thermal range where conditions are optimal, but evidence in support of this hypothesis is mixed and limited in geographical and taxonomic scope. We tested the applicability of the abundant‐centre hypothesis across a range of intertidal organisms using a large, citizen science‐generated data set. Location UK. Methods Species' abundance records were matched with their location within their thermal range. Patterns in abundance distribution for individual species, and across aggregated species abundances, were analysed using Kruskal–Wallis tests and quantile general additive models. Results Individually, invertebrate species showed increasing abundances in the cooler half of the thermal range and decreasing abundances in the warmer half of the thermal range. The overall shape for aggregated invertebrate species abundances reflected a broad peak, with a cool‐skewed maximum abundance. Algal species showed little evidence for an abundant‐centre distribution individually, but overall the aggregated species abundances suggested a hump‐backed abundance distribution. Main Conclusions Our study follows others in showing mixed support for the abundant‐centre hypothesis at an individual species level, but demonstrates an increased predictability in species responses when an aggregated overall response is considered.
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
Most ecosystems are affected by multiple anthropogenic stressors simultaneously, however, there is a lack of information describing the cumulative effects of many common stressor pairs. Consequently, we have but a rudimentary understanding of the roles that stressor characteristics and environmental context play in determining interactions among stressors. Nutrient enrichment often affects coastal ecosystems that may have already been affected by invasive species. To identify the effects of nutrient enrichment on communities under different invasion scenarios, the presence of the invasive fucoid algae, Sargassum muticum, and nutrient conditions were manipulated in the field to test for their independent and cumulative effects. Their combined effects on the diversity and functioning of rock pool communities were quantified. Rock pools with S. muticum contained fewer species, lower macroalgal and microalgal biomass, and their overall benthic assemblage structure differed from pools without S. muticum. Both the presence of S. muticum and nutrient enrichment affected different functional groups of algae differently. Their cumulative effects, however, did not differ with increasing intensity of nutrient enrichment. Furthermore, invaded communities from which S. muticum had been removed manually, tended towards greater species richness following removal than pools where S. muticum remained present, indicating a potential for recovery. These findings highlight the importance of identifying the cumulative effects of multiple stressors on the responses of individual functional groups, alongside effects on overall assemblage structure, in order to fully understand the consequences for ecosystems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.