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- Arvidsson, Björn L, 1952-, et al.
(författare)
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Recruitment of the threatened mussel Margaritifera margaritifera in relation to mussel population size, mussel density and host density
- 2012
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Ingår i: Aquatic conservation. - Malden, MA : John Wiley & Sons. - 1052-7613 .- 1099-0755. ; 22, s. 526-532
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic, abiotic factors are considered main causes of recruitment failure of unionid mussels, including the freshwater pearl mussel (Margaritifera margaritifera). In this large-scale investigation, we instead examined the relationship between biotic factors and mussel recruitment.Juvenile mussel density was positively related to both mussel population size and density of which the last appeared to be a more accurate measure of recruitment.Host fish density of young-of-the-year and older brown trout (Salmo trutta) were positively related to recruitment. Moreover, the mean density of both age classes of fish, when grouped into density classes was positively related to juvenile mussel density, an effect that decreased at trout densities above 10 trout 100 m-2.There was a higher relative importance of mussel population size and density than trout density to recruitment.To increase recruitment of juvenile mussels, managers may apply measures that increase mussel density, and trout density up to about 10 trout 100 m-2 in connection to mussel beds. Mussel beds may also be managed and one possible measure within small and sparse mussel populations may be to concentrate the remaining mussels to areas where trout density is high. Likewise, young-of-the-year trout may also be moved to areas of high mussel density, as young trout individuals are relatively resident during their first year. This may increase mussel larval infection rates and mussel recruitment.
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- Österling, Martin E, 1970-, et al.
(författare)
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Habitat degradation and the decline of the threatened mussel Margaritifera maragaritifera: influence of turbidity and sedimentation on mussel an its host
- 2010
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 47:4, s. 759-768
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Tidskriftsartikel (refereegranskat)abstract
- 1. Habitat degradation is a major reason for species extinctions. For parasite–host interactions, the decline of a parasite may not only be related to the parasite’s tolerance to habitat degradation but also indirectly through the host’s tolerance to the same disturbance.2. Our objective was to explore the cause of population declines of the freshwater pearl mussel Margaritifera margaritifera by relating the age distribution, density and growth of the mussels with turbidity, sedimentation rates and density of the mussel’s host, trout Salmo trutta, in 26 Swedish streams.3. An analysis of the age structure of nine mussel populations showed that maximum age differed by 60 years, with five populations having low proportions of juvenile mussels. Adult mussel density was higher at sites where juvenile mussels occurred than at sites lacking juvenile mussels.4. Growth of adult mussels during the past 10 years was lower in the five streams lacking recent recruitment than in the four streams with recent recruitment, indicating that some environmental factor may be negatively impacting these populations.5. A comparison among 24 populations indicated that turbidity and sedimentation may be responsible for recruitment failure in 58% of the populations. The age of the youngest mussel was positively related to turbidity and sedimentation, and juvenile mussel density was negatively related to turbidity and sedimentation. In contrast, trout density was not related to recruitment of mussels or sedimentation, but was positively related to turbidity in all streams, both with and without recent mussel recruitment.6. Synthesis and applications. Recruitment failure of M. margaritifera appears to be related to its own vulnerability to turbidity and sedimentation rather than to its host’s response to this type of habitat degradation. The results from our study suggest that managers might be able to evaluate the potential viability of mussel populations by measuring stream turbidity. Restoration activities to improve the mussels’ environment should focus on reducing fine material transport into streams.
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- Österling, Martin, 1970-, et al.
(författare)
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Relationship of biotic and abiotic factors to recruitment patterns in Margaritifera margaritifera
- 2008
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Ingår i: Biological Conservation. - : Elsevier. - 0006-3207 .- 1873-2917. ; 141:5, s. 1365-1370
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Tidskriftsartikel (refereegranskat)abstract
- We investigated relationships of biotic and abiotic factors to recruitment patterns of the endangered freshwater pearl mussel (Margaritifera margaritifera) in 10 Swedish streams. We found that the maximum proportion of gravid mussels did not differ between streams with and without recent recruitment. Moreover, the mean glochidial load on trout (Salmo trutta), which was positively related to adult mussel density, did not differ significantly between these stream types. Thus, the larval stages of the freshwater pearl mussel were not related to recruitment failure. Instead, recruitment is probably hindered at the next stage in the life history of the mussels, the benthic stage, and may be related to sedimentation as turbidity was four times greater in streams lacking recent recruitment than in streams with recent recruitment. Furthermore, we found that juvenile mussel density was positively related to the number of glochidial infections per stream area in streams with ongoing recruitment, indicating that successful recruitment in these streams may depend on both mussel and trout density. Future research should thus examine biotic interactions between mussels and trout as well as the effects of sedimentation on benthic-living mussels.
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