| 1. |
- Alsterberg, Christian, 1982, et al.
(författare)
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Consumers mediate the effects of experimental ocean acidification and warming on primary producers.
- 2013
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Ingår i: Proceedings of the National Academy of Science of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 110:21, s. 8603-8608
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that ocean acidification can have profound impacts on marine organisms. However, we know little about the direct and indirect effects of ocean acidification and also how these effects interact with other features of environmental change such as warming and declining consumer pressure. In this study, we tested whether the presence of consumers (invertebrate mesograzers) influenced the interactive effects of ocean acidification and warming on benthic microalgae in a seagrass community mesocosm experiment. Net effects of acidification and warming on benthic microalgal biomass and production, as assessed by analysis of variance, were relatively weak regardless of grazer presence. However, partitioning these net effects into direct and indirect effects using structural equation modeling revealed several strong relationships. In the absence of grazers, benthic microalgae were negatively and indirectly affected by sediment-associated microalgal grazers and macroalgal shading, but directly and positively affected by acidification and warming. Combining indirect and direct effects yielded no or weak net effects. In the presence of grazers, almost all direct and indirect climate effects were nonsignificant. Our analyses highlight that (i) indirect effects of climate change may be at least as strong as direct effects, (ii) grazers are crucial in mediating these effects, and (iii) effects of ocean acidification may be apparent only through indirect effects and in combination with other variables (e.g., warming). These findings highlight the importance of experimental designs and statistical analyses that allow us to separate and quantify the direct and indirect effects of multiple climate variables on natural communities.
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| 2. |
- Eklöf, Johan, 1978, et al.
(författare)
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Community-level effects of rapid experiment warming and consumer loss outweigh effects of rapid ocean acidification.
- 2015
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 124:8, s. 1040-1049
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and consumer loss simultaneously affect marine ecosystems, but we have limited understanding of the relative importance of these factors and the interactions between them. Moreover, effects of environmental change are mediated by organism traits or life histories, which determine their sensitivity. Yet, trait-based analyses have rarely been used to understand the effects of climate change, especially in the marine environment. Here we used a five-week mesocosm experiment to assess the single and interactive effects of 1) rapid ocean warming, 2) rapid ocean acidification, and 3) simulated consumer loss, on the diversity and composition of macrofauna communities in eelgrass Zostera marina beds. Experimental warming (ambient versus + 3.2°C) and loss of a key consumer (the omnivorous crustacean, Gammarus locusta) both increased macrofauna richness and abundance, and altered overall species trait distributions and life history composition. Warming and consumer-loss favored poorly defended epifaunal crustaceans (tube-building amphipods), and species that brood their offspring. We suggest these organisms were favored because warming and consumer-loss caused increased metabolism, food supply and, potentially, settling substrate, and lowered predation pressure from the omnivorous G. locusta. Importantly, we found no single, or interactive, effects of the rapid ocean acidification (ambient versus −0.35 pH units). We suggest this result reflects natural variability in the native habitat and, potentially, the short duration of the experiment: organisms in these communities routinely experience rapid diurnal pH fluctuations that exceed the mean ocean acidification predicted for the coming century (and used in our experiments). In summary, our study indicates that macrofauna in shallow vegetated ecosystems will be significantly more affected by rapid warming and consumer diversity loss than by rapid ocean acidification.
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| 3. |
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| 4. |
- Eklöf, Johan, 1978, et al.
(författare)
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Experimental climate change weakens the insurance effect of biodiversity
- 2012
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 15:8, s. 864-872
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Tidskriftsartikel (refereegranskat)abstract
- Ecosystems are simultaneously affected by biodiversity loss and climate change, but we know little about how these factors interact. We predicted that climate warming and CO 2-enrichment should strengthen trophic cascades by reducing the relative efficiency of predation-resistant herbivores, if herbivore consumption rate trades off with predation resistance. This weakens the insurance effect of herbivore diversity. We tested this prediction using experimental ocean warming and acidification in seagrass mesocosms. Meta-analyses of published experiments first indicated that consumption rate trades off with predation resistance. The experiment then showed that three common herbivores together controlled macroalgae and facilitated seagrass dominance, regardless of climate change. When the predation-vulnerable herbivore was excluded in normal conditions, the two resistant herbivores maintained top-down control. Under warming, however, increased algal growth outstripped control by herbivores and the system became algal-dominated. Consequently, climate change can reduce the relative efficiency of resistant herbivores and weaken the insurance effect of biodiversity.
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| 5. |
- Gamfeldt, Lars, 1975, et al.
(författare)
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Increasing intraspecific diversity enhances settling success in a marine invertebrate
- 2005
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Ingår i: Ecology. - : Wiley. - 0012-9658. ; 86:12, s. 3219-3224
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical and empirical research during the last decade suggests that increasing species richness often enhances ecosystem processes Such as productivity, nutrient cycling. or resistance to disturbance. By analogous reasoning, it can be hypothesized that genetic diversity within species will have equivalent effects; however, this hypothesis has rarely been tested. We present experimental support for the positive effects of intraspecific diversity on a key trait: larval settlement in a marine invertebrate, the barnacle Balanus improvisus. Varying within-species diversity levels of an animal over nine experiments, We found increasing larval settlement with increasing diversity (one, two, or three parental broods). Possible mechanisms explaining this pattern include: (1) facilitation of gregarious response through the presence of founder genotypes, and (2) ensuring genetic complementarity to increase future reproductive potential. Our results indicate that changing intraspecific genetic diversity could have hitherto unrecognized community-scale implications for larval recruitment and space occupancy.
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