| 1. |
- de Boer, M. Karin, et al.
(författare)
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Dispersal restricts local biomass but promotes the recovery of metacommunities after temperature stress
- 2014
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 123:6, s. 762-768
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Tidskriftsartikel (refereegranskat)abstract
- Landscape connectivity can increase the capacity of communities to maintain their function when environments change by promoting the immigration of species or populations with adapted traits. However, high immigration may also restrict fine tuning of species compositions to local environmental conditions by homogenizing the community. Here we demonstrate that dispersal generates such a tradeoff between maximizing local biomass and the capacity of model periphyton metacommunities to recover after a simulated heat wave. In non-disturbed metacommunities, dispersal decreased the total biomass by preventing differentiation in species composition between the local patches making up the metacommunity. On the contrary, in metacommunities exposed to a realistic summer heat wave, dispersal promoted recovery by increasing the biomass of heat tolerant species in all local patches. Thus, the heat wave reorganized the species composition of the metacommunities and after an initial decrease in total biomass by 38.7%, dispersal fueled a full recovery of biomass in the restructured metacommunities. Although dispersal may decrease equilibrium biomass, our results highlight that connectivity is a key requirement for the response diversity that allows ecological communities to adapt to climate change through species sorting.
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| 2. |
- Eklöf, Johan, 1978-, et al.
(författare)
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Habitat-Mediated Facilitation and Counteracting Ecosystem Engineering Interactively Influence Ecosystem Responses to Disturbance
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203.
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Tidskriftsartikel (refereegranskat)abstract
- Recovery of an ecosystem following disturbance can be severely hampered or even shift altogether when a point disturbance exceeds a certain spatial threshold. Such scale-dependent dynamics may be caused by preemptive competition, but may also result from diminished self-facilitation due to weakened ecosystem engineering. Moreover, disturbance can facilitate colonization by engineering species that alter abiotic conditions in ways that exacerbate stress on the original species. Consequently, establishment of such counteracting engineers might reduce the spatial threshold for the disturbance, by effectively slowing recovery and increasing the risk for ecosystem shifts to alternative states. We tested these predictions in an intertidal mudflat characterized by a two-state mosaic of hummocks (humps exposed during low tide) dominated by the sediment-stabilizing seagrass Zostera noltii) and hollows (low-tide waterlogged depressions dominated by the bioturbating lugworm Arenicola marina). In contrast to expectations, seagrass recolonized both natural and experimental clearings via lateral expansion and seemed unaffected by both clearing size and lugworm addition. Near the end of the growth season, however, an additional disturbance (most likely waterfowl grazing and/or strong hydrodynamics) selectively impacted recolonizing seagrass in the largest (1 m2) clearings (regardless of lugworm addition), and in those medium (0.25 m2) clearings where lugworms had been added nearly five months earlier. Further analyses showed that the risk for the disturbance increased with hollow size, with a threshold of 0.24 m2. Hollows of that size were caused by seagrass removal alone in the largest clearings, and by a weaker seagrass removal effect exacerbated by lugworm bioturbation in the medium clearings. Consequently, a sufficiently large disturbance increased the vulnerability of recolonizing seagrass to additional disturbance by weakening seagrass engineering effects (sediment stabilization). Meanwhile, the counteracting ecosystem engineering (lugworm bioturbation) reduced that threshold size. Therefore, scale-dependent interactions between habitat-mediated facilitation, competition and disturbance seem to maintain the spatial two-state mosaic in this ecosystem.
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| 3. |
- Eriksson, Britas Klemens, et al.
(författare)
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Cascading predator control interacts with productivity to determine the trophic level of biomass accumulation in a benthic food web
- 2012
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Ingår i: Ecological research. - : Wiley. - 0912-3814 .- 1440-1703. ; 27:1, s. 203-210
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale exploitation of higher trophic levels by humans, together with global-scale nutrient enrichment, highlights the need to explore interactions between predator loss and resource availability. The hypothesis of exploitation ecosystems suggests that top-down and bottom-up control alternate between trophic levels, resulting in a positive relationship between primary production and the abundance of every second trophic level. Specifically, in food webs with three effective trophic levels, primary producers and predators should increase with primary production, while in food webs with two trophic levels, only herbivores should increase. We provided short-term experimental support for these model predictions in a natural benthic community with three effective trophic levels, where the number of algal recruits, but not the biomass of gastropod grazers, increased with algal production. In contrast, when the food web was reduced to two trophic levels by removing larger predators, the number of algal recruits was unchanged while gastropod grazer biomass increased with algal production. Predator removal only affected the consumer-controlled early life-stages of algae, indicating that both the number of trophic levels and the life-stage development of the producer trophic level determine the propagation of trophic cascades in benthic systems. Our results support the hypothesis that predators interact with resource availability to determine food-web structure.
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| 4. |
- Eriksson, Britas Klemens, et al.
(författare)
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Effects of Altered Offshore Food Webs on Coastal Ecosystems Emphasize the Need for Cross-Ecosystem Management
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:7, s. 786-797
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Forskningsöversikt (refereegranskat)abstract
- By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important links between offshore and coastal systems are restored.
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| 5. |
- Eriksson, Britas Klemens, et al.
(författare)
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Omnivory and grazer functional composition moderate cascading trophic effects in experimental Fucus vesiculosus habitats
- 2011
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 158:4, s. 747-756
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Tidskriftsartikel (refereegranskat)abstract
- We tested the relative strength of direct versus indirect effects of an aquatic omnivore depending on the functional composition of grazers by manipulating the presence of gastropod and amphipod grazers and omnivorous shrimp in outdoor mesocosms. By selectively preying upon amphipods and reducing their abundance by 70-80%, omnivorous shrimp favoured the dominance of gastropods. While gastropods were the main microalgal grazers, amphipods controlled macroalgal biomass in the experiment. However, strong predation on the amphipod by the shrimp had no significant indirect effects on macroalgal biomass, indicating that when amphipod abundances declined, complementary feeding by the omnivore on macroalgae may have suppressed a trophic cascade. Accordingly, in the absence of amphipods, the shrimp grazed significantly on green algae and thereby suppressed the diversity of the macroalgal community. Our experiment demonstrates direct consumer effects by an omnivore on both the grazer and producer trophic levels in an aquatic food web, regulated by prey availability.
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| 6. |
- Eriksson, Jörgen, et al.
(författare)
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Parallellpublicering av konferensartiklar : principer, tillämpningar och tillgänglighet i svenska publiceringsdatabaser
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektets huvudsyfte har varit att undersöka kvalitetsgranskade konferensartiklars tillgänglighet samt konferensers OA- och publiceringspolicies för att på så sätt klarlägga olika aspekter vad det gäller parallellpublicering i svenska publiceringsdatabaser. För ändamålet har projektdeltagarna undersökt ett urval konferenser och konferensartiklar via sina publiceringsdatabaser under ett specifikt tidsintervall och beskrivit dem utifrån ett gemensamt schema.Undersökningen har visat att publiceringsdatabaserna fyller en viktig funktion för att synliggöra konferenspublikationer. Vi har funnit att minst ca. 50 % av konferensartiklarna kan publiceras som post-prints i våra publiceringsdatabaser. Därför är det av stor vikt att fortsätta arbetet med att utnyttja de lokala publiceringsdatabaserna som publiceringskanal och att inte bara använda dem som ett verktyg för parallellpublicering och primärpublicerat material, som avhandlingar och rapporter, utan även som en källa framförallt för konferensartiklar ”utan hem”, som vi nu vet utgör en stor del av vårt undersökningsmaterial (ca. 15 %).Mellan 20-25 % av de undersökta artiklarna fanns i något slags öppet OA-arkiv; ca. hälften av dessa fanns i någon av projektdeltagarnas egen publiceringsdatabas. Detta talar för att den egna publiceringsdatabasen är en viktig faktor för öppen tillgänglighet.Ca. 10% av konferenserna i studien hade en uttrycklig OA-policy eller gav uttryck för en sådan genom att öppet tillgängliggöra konferensartiklar på sina konferenssajter. Ett stort problem när det gäller parallellpublicering av konferensartiklar är just bristen på information om OA-policy.Konferenspubliceringslandskapet är komplicerat och parallellpubliceringen av dokument härifrån är mycket tidskrävande. Vi skulle framför allt önska en liknande policy-resurs som SHERPA/RoMEO för konferenser. Men för närvarande finns inget annat alternativ än att lusläsa konferensernas upphovsrättsinformation till författarna och av denna försöka dra slutsatser om ev. parallellpublicering.För att underlätta framtida hantering och klassificering av konferensartiklar i svenska publicerings-databaser, framför allt med tanke på ev. framtida nationella bibliometriska analyser via SwePub, föreslås ett antal rekommendationer.
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| 7. |
- Linde, Peter, et al.
(författare)
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Accessibility and self-archiving of conference articles : A study on a selection of Swedish institutional repositories
- 2011
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Ingår i: Information Services and Use. - Guimarães : IOS Press. - 0167-5265 .- 1875-8789. ; 31:3-4, s. 259-269, s. 123-
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this project has been to examine the accessibility of refereed conference articles and the OA- and publishing policies of conferences in order to in this way elucidate different aspects concerning self-archiving in Swedish institutional repositories. For this purpose, the project participants have examined a number of conferences and references to conference articles via their institutional repositories during a specific time period and described these from the perspective of a common scheme. The study has showed that the local institutional repositories fill an important role to make conference publications visible. We have found that ca. 50% of the conference papers can be published as postprints in our institutional repositories. We have noticed that ca. 15% or the studied conference articles are not available at all. It is, therefore, of great importance to use local institutional repositories as a publishing channel, not only for primary published material such as dissertations and reports, but also as a source for finding these conference articles "without a home". Between 20-25% of the examined articles were found in some type of OA archive; ca. half of these were found in one of the project participants' own institutional repositories. This indicates that the publishing database of respective higher education institution is an important factor for open accessibility. Ca. 10% of the conferences in the study had an explicit OA policy or expressed such a policy by openly making conference articles accessible on their conference sites. A big problem when it comes to self-archiving of conference articles is the lack of information about OA policy. The landscape of conference publishing is complex and the self-archiving of documents from conferences is very time-consuming. Above all, we would wish a policy resource for conferences similar to the SHERPA/RoMEO. At present, however, there is no other alternative than scrutinizing the conferences' copyright information to the authors and from this attempt to draw conclusions about possible self-archiving. To facilitate the future handling and classification of conference articles in Swedish institutional repositories a number of recommendations are suggested.
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| 8. |
- Ljunggren, Lars, et al.
(författare)
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Recruitment failure of coastal predatory fish in the Baltic Sea coincident with an offshore ecosystem regime shift
- 2010
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Ingår i: ICES Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 67:8, s. 1587-1595
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Tidskriftsartikel (refereegranskat)abstract
- The dominant coastal predatory fish in the southwestern Baltic Sea, perch and pike, have decreased markedly in abundance during the past decade. An investigation into their recruitment at 135 coastal sites showed that both species suffered from recruitment failures, mainly in open coastal areas. A detailed study of 15 sites showed that areas with recruitment problems were also notable for mortality of early-stage larvae at the onset of exogenous food-intake. At those sites, zooplankton abundance predicted 83 and 34% of the variation in young of the year perch and pike, respectively, suggesting that the declines were caused by recruitment failure attributable to zooplankton food limitation. Incidences of recruitment failure match in time an offshore trophic cascade that generated massive increases in planktivorous sprat and decreases in zooplankton biomass in the early 1990s. Therefore, sprat biomass explained 53% of the variation in perch recruitment from 1994 to 2007 at an open coastal site, where three-spined stickleback also increased exponentially after 2002. The results indicate that the dramatic change in the offshore ecosystem may have propagated to the coast causing declines of the dominating coastal predators perch and pike followed by an increase in the abundance of small-bodied fish.
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