| 1. |
- Gross, C. P., et al.
(författare)
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The biogeography of community assembly: latitude and predation drive variation in community trait distribution in a guild of epifaunal crustaceans
- 2022
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 289:1969
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Tidskriftsartikel (refereegranskat)abstract
- While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (Zostera marina) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.
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| 2. |
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| 3. |
- Dahl, Martin, 1984-, et al.
(författare)
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A 2,000-Year Record of Eelgrass (Zostera marina L.) : Colonization Shows Substantial Gains in Blue Carbon Storage and Nutrient Retention
- 2024
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Ingår i: Global Biogeochemical Cycles. - : John Wiley & Sons. - 0886-6236 .- 1944-9224. ; 38:3
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Tidskriftsartikel (refereegranskat)abstract
- Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20- and 24-fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services. © 2024. The Authors.
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| 4. |
- Duffy, J. Emmett, et al.
(författare)
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A Pleistocene legacy structures variation in modern seagrass ecosystems
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:32
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Tidskriftsartikel (refereegranskat)abstract
- Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (Zostera marina), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.
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| 5. |
- Duffy, J. E., et al.
(författare)
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Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach
- 2015
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 18:7, s. 696-705
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Tidskriftsartikel (refereegranskat)abstract
- Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors.
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| 6. |
- Ariza, A., et al.
(författare)
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Structure and Activity of a Paenibacillus polymyxa Xyloglucanase from Glycoside Hydrolase Family 44
- 2011
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 286:39, s. 33890-33900
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Tidskriftsartikel (refereegranskat)abstract
- The enzymatic degradation of plant polysaccharides is emerging as one of the key environmental goals of the early 21st century, impacting on many processes in the textile and detergent industries as well as biomass conversion to biofuels. One of the well known problems with the use of nonstarch (nonfood)-based substrates such as the plant cell wall is that the cellulose fibers are embedded in a network of diverse polysaccharides, including xyloglucan, that renders access difficult. There is therefore increasing interest in the "accessory enzymes," including xyloglucanases, that may aid biomass degradation through removal of "hemicellulose" polysaccharides. Here, we report the biochemical characterization of the endo-beta-1,4-(xylo)glucan hydrolase from Paenibacillus polymyxa with polymeric, oligomeric, and defined chromogenic aryl-oligosaccharide substrates. The enzyme displays an unusual specificity on defined xyloglucan oligosaccharides, cleaving the XXXG-XXXG repeat into XXX and GXXXG. Kinetic analysis on defined oligosaccharides and on aryl-glycosides suggests that both the -4 and +1 subsites show discrimination against xylose-appended glucosides. The three-dimensional structures of PpXG44 have been solved both in apo-form and as a series of ligand complexes that map the -3 to -1 and +1 to +5 subsites of the extended ligand binding cleft. Complex structures are consistent with partial intolerance of xylosides in the -4' subsites. The atypical specificity of PpXG44 may thus find use in industrial processes involving xyloglucan degradation, such as biomass conversion, or in the emerging exciting applications of defined xyloglucans in food, pharmaceuticals, and cellulose fiber modification.
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| 7. |
- Peterson, Stefan, et al.
(författare)
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Classification of thyroid size by palpation and ultrasonography in field surveys
- 2000
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 355, s. 106-110
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Goitre surveys are used to assess the degree of iodine deficiency in a population. The change of goitre classification made by WHO in 1994 implied that a smaller thyroid size should be regarded as goitre. Furthermore, the acceptable goitre prevalence was lowered from 10% to 5%, and ultrasonography was recommended as a more precise method for diagnosis of goitre. We studied the effects of the change of palpation system, and compared the precision of the old and new systems with that of ultrasonographic examination. METHODS: We studied 225 schoolchildren (aged 7-14 years) in a highland village in Tanzania. The size of the thyroid was assessed in duplicate by ultrasonography and by WHO's 1960 and 1994 palpation systems. The latter were done by three examiners. Variations within and between examination methods and examiners were assessed, and measurement errors by ultrasonography were assessed from duplicate examinations. The sensitivity and specificity of the two palpation systems were calculated, with diagnosis by ultrasonography as the gold standard. Apparent palpation prevalences were calculated at a "true" 5% prevalence. FINDINGS: The lowered criterion for goitre resulted in an extra 20-33% of children being diagnosed as having goitre by palpation. The variation between repeat examinations was only slightly smaller by ultrasonography (kappa=0.63) than by experienced examiners (kappa=0.57-0.58). The variation between thyroid volume estimation by ultrasonography and the true volume was about 50% due to both measurement error and variation in the shape of thyroid lobes. The new goitre criterion decreased specificity from 76% to 29%, whereas sensitivity rose from 56% to 80%. In contrast, a suggested sharpening of the old criterion increased specificity to 90%. INTERPRETATION: A return to the old (1960) palpation criterion for goitre: "lobes larger than the terminal phalanxes of thumbs" and to an accepted palpation goitre prevalence of 10% can allow affordable monitoring of thyroid size through palpation in field surveys.
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| 8. |
- Röhr, Maria Emilia, et al.
(författare)
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Blue Carbon Storage Capacity of Temperate Eelgrass (Zostera marina) Meadows
- 2018
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 32:10, s. 1457-1475
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Tidskriftsartikel (refereegranskat)abstract
- Despite the importance of coastal ecosystems for the global carbon budgets, knowledge of their carbon storage capacity and the factors driving variability in storage capacity is still limited. Here we provide an estimate on the magnitude and variability of carbon stocks within a widely distributed marine foundation species throughout its distribution area in temperate Northern Hemisphere. We sampled 54 eelgrass (Zostera marina) meadows, spread across eight ocean margins and 36° of latitude, to determine abiotic and biotic factors influencing organic carbon (Corg) stocks in Zostera marina sediments. The Corg stocks (integrated over 25-cm depth) showed a large variability and ranged from 318 to 26,523gC/m2 with an average of 2,721gC/m2. The projected Corg stocks obtained by extrapolating over the top 1m of sediment ranged between 23.1 and 351.7MgC/ha, which is in line with estimates for other seagrasses and other blue carbon ecosystems. Most of the variation in Corg stocks was explained by five environmental variables (sediment mud content, dry density and degree of sorting, and salinity and water depth), while plant attributes such as biomass and shoot density were less important to Corg stocks. Carbon isotopic signatures indicated that at most sites <50% of the sediment carbon is derived from seagrass, which is lower than reported previously for seagrass meadows. The high spatial carbon storage variability urges caution in extrapolating carbon storage capacity between geographical areas as well as within and between seagrass species.
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| 9. |
- Aperia, A, et al.
(författare)
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The renal dopamine system
- 1998
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Ingår i: Advances in pharmacology (San Diego, Calif.). - : Elsevier. - 1054-3589. ; 42, s. 870-3
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Tidskriftsartikel (refereegranskat)
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| 10. |
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