| 1. |
- Andrén, Mats, et al.
(författare)
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Att lära sig språk
- 2013
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Ingår i: Språket, människan och världen : människans språk 1-2 - människans språk 1-2. - Lund : Studentlitteratur AB. - 9789144083391 ; , s. 73-89
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Bokkapitel (populärvet., debatt m.m.)
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| 2. |
- Asplund, Maria. E., 1970, et al.
(författare)
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Methane Emissions From Nordic Seagrass Meadow Sediments
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Shallow coastal soft bottoms are important carbon sinks. Submerged vegetation has been shown to sequester carbon, increase sedimentary organic carbon (C-org) and thus suppress greenhouse gas (GHG) emissions. The ongoing regression of seagrass cover in many areas of the world can therefore lead to accelerated emission of GHGs. In Nordic waters, seagrass meadows have a high capacity for carbon storage, with some areas being recognized as blue carbon hotspots. To what extent these carbon stocks lead to emission of methane (CH4) is not yet known. We investigated benthic CH4 emission (i.e., net release from the sediment) in relation to seagrass (i.e. Zostera marina) cover and sedimentary C-org content (%) during the warm summer period (when emissions are likely to be highest). Methane exchange was measured in situ with benthic chambers at nine sites distributed in three regions along a salinity gradient from similar to 6 in the Baltic Sea (Finland) to similar to 20 in Kattegat (Denmark) and similar to 26 in Skagerrak (Sweden). The net release of CH4 from seagrass sediments and adjacent unvegetated areas was generally low compared to other coastal habitats in the region (such as mussel banks and wetlands) and to other seagrass areas worldwide. The lowest net release was found in Finland. We found a positive relationship between CH4 net release and sedimentary C-org content in both seagrass meadows and unvegetated areas, whereas no clear relationship between seagrass cover and CH4 net release was observed. Overall, the data suggest that Nordic Zostera marina meadows release average levels of CH4 ranging from 0.3 to 3.0 mu g CH4 m(-2) h(-1), which is at least 12-78 times lower (CO2 equivalents) than their carbon accumulation rates previously estimated from seagrass meadows in the region, thereby not hampering their role as carbon sinks. Thus, the relatively weak CH4 emissions from Nordic Z. marina meadows will not outweigh their importance as carbon sinks under present environmental conditions.
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| 3. |
- Baden, Susanne P., 1952, et al.
(författare)
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Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community
- 2022
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X. ; 177
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a short-term field sampling complemented with time integrating stable isotope analysis to ho- listically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya.
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| 4. |
- Bergström, Per, 1980, et al.
(författare)
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Testing the potential for improving quality of sediments impacted by mussel farms using bioturbating polychaete worms
- 2017
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Ingår i: Aquaculture Research. - : Hindawi Limited. - 1365-2109 .- 1355-557X. ; 48:1, s. 161-176
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Tidskriftsartikel (refereegranskat)abstract
- Biodeposits from farmed mussels severely influence the biogeochemistry of sediments by increasing the levels of organic matter (OM). Mitigation of such negative impacts is important for the development of sustainable aquaculture operations. As a step towards developing methods for remediation of coastal sediments affected by mussel farming, the effects of the polychaete, Hediste diversicolor was evaluated experimentally. In a series of field- and laboratory experiments we tested hypotheses about the effects of polychaetes on sediment oxygen consumption, nutrient fluxes and sulphide pools under different polychaete densities and sedimentation regimes. The experimental results support the idea that polychaetes can mitigate negative effects on the benthic environment beneath mussel farms. H.diversicolor oxidized the sediment and generally enhanced the oxygen consumption, and thus the decomposition of OM. The accumulation of pore water sulphides were reduced and fluxes of nutrients across the sediment-water interface increased. Additional calculations suggest that the effects of polychaetes were mainly indirect and driven by increased microbial activity due to the borrowing activity of the polychaetes. Trends of increasing decomposition with increasing polychaete density suggest that the decomposition could be further enhanced by higher densities. Overall, we concluded that H.diversicolor is a potentially strong candidate for remediation of mussel farm sediments. The results show that sediments inhabited by H.diversicolor have high assimilative capacity of OM and oxygen conditions are significantly improved following the addition of polychaetes at naturally occurring densities. However, technological developments are needed in order to allow the approach to be used in practice.
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| 5. |
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| 6. |
- de Fouw, Jimmy, et al.
(författare)
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A facultative mutualism facilitates European seagrass meadows
- 2023
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Ingår i: Ecography. - 0906-7590 .- 1600-0587. ; 2023:5
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Tidskriftsartikel (refereegranskat)abstract
- Coastal ecosystem functioning often hinges on habitat-forming foundation species that engage in positive interactions (e.g. facilitation and mutualism) to reduce environmental stress. Seagrasses are important foundation species in coastal zones but are rapidly declining with losses typically linked to intensifying global change-related environmental stress. There is growing evidence that loss or disruption of positive interactions can amplify coastal ecosystem degradation as it compromises its stress mitigating capacity. Multiple recent studies highlight that seagrass can engage in a facultative mutualistic relationship with lucinid bivalves that alleviate sulphide toxicity. So far, however, the generality of this mutualism, and how its strength and relative importance depend on environmental conditions, remains to be investigated. Here we study the importance of the seagrass-lucinid mutualistic interaction on a continental-scale using a field survey across Europe. We found that the lucinid bivalve Loripes orbiculatus is associated with the seagrasses Zostera noltii and Zostera marina across a large latitudinal range. At locations where the average minimum temperature was above 1 °C, L. orbiculatus was present in 79% of the Zostera meadows; whereas, it was absent below this temperature. At locations above this minimum temperature threshold, mud content was the second most important determinant explaining the presence or absence of L. orbiculatus. Further analyses suggest that the presence of the lucinids have a positive effect on seagrass biomass by mitigating sulphide stress. Finally, results of a structural equation model (SEM) support the existence of a mutualistic feedback between L. orbiculatus and Z. noltii. We argue that this seagrass-lucinid mutualism should be more solidly integrated into management practices to improve seagrass ecosystem resilience to global change as well as the success of restoration efforts.
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| 7. |
- Holmer, Marianne, et al.
(författare)
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Aquaculture and eutrophication.
- 2008
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Ingår i: Assessment of climate change for the Baltic Sea basin by The BACC Author Team. - : Springer, Heidelberg. ; , s. 420-423
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Bokkapitel (refereegranskat)
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| 8. |
- Holmer, Marianne, et al.
(författare)
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Digging worms for remediation of sediments impacted by mussel farms
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Mussel farms affect the biogeochemical conditions in the sediments underneath the farms due to organic enrichment by mussel biodeposits and by mussels falling of the long-lines, which is an unwanted effect of mussel farming (Carlsson et al. 2009). Organically-enriched sediments have high oxygen consumption rates contributing to oxygen depletion events. High efflux rates of nutrients such as ammonium and phosphate, contributing to eutrophication, are also observed together with accumulation of sulphides, which prevent benthic infauna from colonizing and surviving in the sediments. Thus, a low biodiversity is in general observed in this environment. Burrowing polychaetes have the potential to stimulate the decomposition of mussel biodeposits in a similar way as has been observed underneath fish farm (Heilskov et al. 2006, Sanz-Lazaro et al. 2011). This increases the assimilative capacity of the sediments (Hargrave et al. 2008) and avoids deterioration of the sediment conditions. In this study, the prediction that polychaetes counteract the negative effects of organic enrichment in mussel farms are addressed by conducting a number of field and laboratory studies using the organic tolerant polychaete, Capitella sp., and the less tolerant but larger polychaete Hediste diversicolor, which are added to sediments affected by organic enrichment from mussel farms. Both polychaetes are native in the study area and Hediste diversicolor has commercial potential as fish feed and as bait for anglers (Bischoff et al. 2009). Sediment oxygen uptake, nutrient fluxes and pools of sulphides were measured in the field 5 weeks after the two polychaetes were added in different densities to mussel farm sediment and compared to reference sediment. In the lab experiment, sediments were collected from a reference site and manipulated with different densities of polychaetes and doses of mussel biodeposits. Short-term (hours, days) dynamics in sediment oxygen uptake and nutrient fluxes were measured. The results showed that H. diversicolor may be a strong candidate for remediation of mussel farm sediments, as it enhances the decomposition of organic matter to a larger extent than observed for other types of organic matter (dried yeast, fish farm waste products). This is probably due to direct consumption of the fecal pellets by the worms as well as mixing of the fecal pellets into the sediments by bioturbation. At the same time, the sediments were oxidized which reduced the accumulation of particular pore water sulphides as well as the iron-bound sulphides (the AVS pool). This may create favourable sediment conditions for recolonization of other infaunal species. In the lab experiment, the positive effects of H. diversicolor occurred within the first day of deposition of organic matter and then rapidly declined, when no further organic matter (fecal pellets) was added. It can be expected that the rates will remain high upon continuous addition as observed in the field, where rates were generally higher in mussel farm compared to reference sediments over the study period. The effects of addition of H. diversicolor on nutrient fluxes were more complex. It did to some extent follow the enhanced decomposition with enhanced release of nutrients from the sediments, in particular right after the organic matter was added, but fluxes of phosphate were more controlled by the biogeochemistry of the sediments, where an uptake was observed in all treatments, probably due to a reoxidation event at the study site. In these experiments H. diversicolor was added at relatively low densities (91-444 m-2) and the trends with increasing density suggests that larger densities, e.g. up to 1000 m2 may enhance the decomposition of biodeposits even further. Compared to H. diversicolor, the effects of Capitella sp. were limited. In the highest densities, the effects on sediment oxygen uptake and nutrient fluxes were similar to the low density of H. diversicolor and there were no apparent effects on the organic matter decomposition under enriched conditions by Capitella. This suggests that Capitella may have limited effects on the decomposition of mussel biodeposits, as compared to H. diversicolor, probably due to the difference in bioturbation activity between the two species. However, to further evaluate the potential of this species, higher densities of Capitella compared to what was used in this experiment should be used.
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| 9. |
- Johansson, Victoria, et al.
(författare)
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Människan och språket
- 2013
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Ingår i: Språket, människan och världen : människans språk 1-2. - Lund : Studentlitteratur AB. - 9789144083391 ; , s. 41-52
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Bokkapitel (populärvet., debatt m.m.)
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| 10. |
- Moksnes, Per-Olav, 1965, et al.
(författare)
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Major impacts and societal costs of seagrass loss on sediment carbon and nitrogen stocks
- 2021
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows constitute important carbon sinks, and the ongoing global loss of seagrass habitats raises concerns about the release of carbon stored in their sediments. However, the actual consequences of seagrass loss for the release of carbon and nutrients remain unclear. Here, we take advantage of well-documented historic losses of eelgrass (Zostera marina) meadows along the Swedish NW coast to assess how the contents of organic carbon (C) and nitrogen (N) in the sediment change when a meadow is lost. We find unusually high contents of C and N (on average 3.7% and 0.39% DW, respectively) in Swedish eelgrass sediments down to >100cm depth, suggesting that these habitats constitute global hot spots for C and N storage. However, the C and N stocks were strongly influenced by wave exposure and were almost twice as high in sheltered compared to exposed eelgrass meadows. The sediment composition and stable isotope values were distinctly different in areas that have lost eelgrass meadows, with on average >2.6 times lower contents of C and N. The results indicate an erosion of >35cm sediment following the historical eelgrass loss, and that sheltered meadows have more vulnerable sediment stocks. The results suggest that eelgrass loss has resulted in a release of 60.2Mg C and 6.63Mg N per hectare, with an estimated economic cost to society of 7944 and 141,355US$/ha, respectively. The value of N storage represents one of the highest monetary values presented for an ecosystem service provided by seagrasses and shows that Swedish eelgrass meadows are particularly important for mitigating eutrophication. Following a documented loss of approximately 10km2 of eelgrass in the study area, it is estimated that over 60,000Mg of nitrogen was released to the coastal environment over a 20-yr period, which constitutes over three times the annual river load of nitrogen to the Swedish NW coast. The study exemplifies the significant role of seagrass sediments as sinks for both carbon and nutrients, and that the risk of nutrient release following vegetation loss should be taken into account in the spatial management of seagrass and other coastal habitats.
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