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- Bergström, Per, 1980, et al.
(författare)
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Differences in growth patterns among three bivalve species and in relation to exposure and implications for aquaculture and ecological functions
- 2024
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Ingår i: Estuarine, Coastal and Shelf Science. - 0272-7714. ; 303
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, similarities and differences in growth patterns, measured as changes in soft tissue weight and shell length, among three bivalve species in Sweden (blue mussels, Pacific oysters and European flat oysters) were studied with the aim to achieve information on spatial and temporal variability among these commercially important species. The study showed that there are significant differences in spatial growth pattern between blue mussels and both of the oyster species, where oysters grew faster in more protected locations compared to mussels, which had a generally faster growth in the exposed localities. The weight: length ratio also differed among species, where mussels had a lower ratio compared to oysters. Potential causes of the observed patterns and consequences for bivalve farming as well as implications for ecological functions are discussed. The results are valuable in site-selection processes at both local (individual farmers) and regional/national scales (planning processes etc), and indicates that spatial planning of bivalve aquaculture need inclusion of species specific growth parameters.
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| 2. |
- Bergström, Per, 1980, et al.
(författare)
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Identifying high‐density areas of oysters using species distribution modeling: Lessons for conservation of the native Ostrea edulis and management of the invasive Magallana ( Crassostrea ) gigas in Sweden
- 2021
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 11:10, s. 5522-5532
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Tidskriftsartikel (refereegranskat)abstract
- AimUnderstanding spatial patterns of the distribution of adult native oyster, Ostrea edulis, and the invasive Magallana (Crassostrea) gigas is important for management of these populations. The aim of this study was to use ensemble SDM’s to (a) identify and predict conservation hotspots, (b) assess the current level of protection for O. edulis, and (c) quantify the amount of overlap between the two species where interactions with M. gigas are most likely.LocationSkagerrak, Sweden.MethodsWe used data collected by video at depths from 0.5 to 10 m in 436 sites. Models of occurrence and densities >1 m−2 were fitted and assessed using ensemble methods (“biomod2” package). Models of high-density hotspots were used to predict, map, and quantify areal extent of the species in order to assess the degree of overlap with protected areas and the potential for interactions between the two species.ResultsBoth species were widely distributed in the region. Observations of high-density habitats, mainly occurring at depths of ≈3 and 0.5 m for O. edulis and M. gigas, respectively, were found in 4% and 2% of the sites. Models provided useful predictions for both species (AUC = 0.85–0.99; sensitivity = 0.74–1.0; specificity = 0.72–0.97). High-density areas occupy roughly 15 km2 each with substantial overlap between species. 50% of these are protected only by fisheries regulations, 44% are found in Natura 2000 reserves and 6% of the predicted O. edulis enjoys protection in a national park.Main conclusionsData collection by video in combination with SDM’s provides a realistic approach for large-scale quantification of spatial patterns of marine population and habitats. O. edulis and M. gigas are common in the area, but a large proportion of the most valuable O. edulis habitats are not found in protected areas. The overlap between species suggests that efforts to manage the invasive M. gigas need to be integrated with management actions to conserve the native O. edulis.
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| 3. |
- Greeve, Youk, et al.
(författare)
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Estimating and scaling-up biomass and abundance of epi- and infaunal bivalves in a Swedish archipelago region: Implications for ecological functions and ecosystem services.
- 2023
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Introduction As suspension-feeders, bivalves play a key role in maintaining regulatory functions of coastal ecosystems, which are linked to important ecosystem services. The functions attributed to bivalves depend on the life habits of a species (epi- or infauna) and their abundance and biomass. To properly quantify and assess these functions, detailed information the distribution, abundance and biomass at the ecosystem scale is critical. Amongst others, this requires an understanding on how environmental conditions shape special patterns in distribution. In this study we investigate this fundamental information on the Swedish west coast, an area where this information is lacking. Methods A survey which was designed to representatively sample both epi- and infaunal bivalves from randomized locations in various habitat types was conducted. Specifically, abundance and biomass of all species were recorded in the intertidal (0-0.5 m) and the shallow subtidal zone (0.5-2 m). The sites were distributed over an offshore gradient and at two exposure levels. This sampling structure allowed to extrapolate the results to an ecosystem level though information on the areal extent of these habitats using GIS layers. Results It was found that even though there exist a great variability among sites, in general epifaunal bivalves outweigh infaunal bivalves approximately 3 to 1. In terms of abundance, the ratio is more or less reversed and infaunal species occur in greater numbers. Most bivalves were found at an intermediate level of exposure, but due to the areal extend of the sheltered inner-archipelago this was the most important habitat for bivalve abundance and biomass. It was also found that invasive epifaunal oyster Magallana gigas and the invasive infaunal clam Ensis leei both dominated their respective groups in terms of biomass. Discussion Though the survey was relatively small, these results serve as a valuable insight of the relative importance of epi- and infaunal bivalves in this region. This gives understanding on which species and habitats are particularly important for ecosystem functions and services related to bivalves. This also provide a starting baseline for attempts to quantify ecosystem services provided by certain species or groups of bivalves in the future.
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| 4. |
- Palmberg, Mai, 1943-, et al.
(författare)
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Sydafrika : en regnbågsnation föds
- 1995
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Bok (populärvet., debatt m.m.)abstract
- De senaste åren har inneburit omvälvande förändringar i Sydafrika. Denna bok skildrar den tid och de händelser som ledde fram till att Sydafrika förvandlades från en minoritetsstyrd rasistisk diktatur till en demokrati. Författarna diskuterar också de frågor, risker och möjligheter som kan uppstå under övergångstiden mellan det första valet i april 1994 och nästa val 1999. Arvet efter apartheid inom snart sagt alla samhällssektorer diskuteras och ANC:s och den nuvarande samlingsregeringens politik för det nya Sydafrika analyseras.Tillräcklig historisk bakgrund ges för att boken ska kunna läsas utan annan introduktion till landet. Boken kan användas både för enskild läsning och för gruppstudier eller projektstudier i skolan.
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