scholarly journals Effect of substrate particle size on burrowing of the juvenile freshwater pearl mussel Margaritifera margaritifera

Hydrobiologia ◽  
2021 ◽  
Vol 848 (5) ◽  
pp. 1137-1146
Author(s):  
Heini Hyvärinen ◽  
Mari Saarinen-Valta ◽  
Eero Mäenpää ◽  
Jouni Taskinen
Keyword(s):  
Particle Size ◽  
Life Stage ◽  
Margaritifera Margaritifera ◽  
Pearl Mussel ◽  
Freshwater Pearl Mussel ◽  
Juvenile Mortality ◽  
Fine Sediments ◽  
Recruitment Failure ◽  
Substrate Size ◽  
Substrate Particle

AbstractJuveniles of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera) live burrowed in stream substrate for the first years of their life. Fine sediments block water exchange within substrate and may cause juvenile mortality and recruitment failure. To better understand the connection between success of juvenile FPM and substrate particle size, it would be important to understand behavioural responses of FPM to varying substrate sizes at this critical life stage. We placed newly detached FPM juveniles in a 7-mm layer of sieved sand sorted into five sizes (< 120, 120–200, 200–250, 250–500 and 500–650 µm) each with 10 replicate dishes, 10 juveniles per dish, with burrowing status monitored for 96 h. Mean dish-specific proportion burrowed (PB) was significantly affected by substrate size, increasing from 52% in the finest sand to 98% in the coarsest sand. Furthermore, the significant substrate × time interaction was observed due to dropped PB (30-34%) in finest sand at 2–4 h time points. Thus, results suggest a clear behavioural response by juvenile FPM to substrate size, with fine sediments triggering surfacing behaviour. Surfacing may indicate stress, can increase predation risk, and expose to drift and/or enable drift of juveniles.

scholarly journals Assessing Evolutionary Significant Units (ESU) of the Endangered Freshwater Pearl Mussel (Margaritifera margaritifera) in Southeast Norway on the Basis of Genetic Analysis

Genes ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1061
Author(s):  
Arne N. Linløkken ◽  
Silje Garlie ◽  
Wenche Johansen ◽  
Robert C. Wilson
Keyword(s):  
Genetic Diversity ◽  
Salmo Trutta ◽  
Margaritifera Margaritifera ◽  
River Systems ◽  
Pearl Mussel ◽  
Freshwater Pearl Mussel ◽  
Recruitment Failure ◽  
Low Genetic Diversity ◽  
Brown Trout Salmo Trutta ◽  
Hardy Weinberg Equilibrium

A total of 312 specimens of freshwater pearl mussel (Margaritifera margaritifera) were sampled from 11 populations, located in four different river systems in Southeast Norway, and analyzed for 11 simple sequence repeat (SSR) (microsatellite) markers. All study populations have landlocked brown trout (Salmo trutta) as the only possible host. Several populations had experienced recruitment failure, probably due to low pH (about 6.0) and calcium concentration. STRUCTURE clustering analysis revealed two genetic clusters, of which one cluster occurred mainly in the western river systems, and totally dominated in one population (Fallselva (A-FAL)) that had higher genetic diversity than the others. Cluster 2 completely dominated in the populations of the eastern river systems, and all of them had low genetic diversity. Bottleneck events were indicated in all populations and the inbreeding coefficient FIS was significant in all populations, except for the southernmost population (Sørkedalselva (B-SØR)), which was the only population with genotypes in Hardy–Weinberg equilibrium. FIS were especially high in the populations of the eastern river systems, and maximum shell length was negatively correlated to FIS. If artificially breeding and stocking should become necessary for future preservation, it should be based on single populations; alternatively, the eastern populations should be based on cross-breeding of populations within the cluster to increase their genetic diversity.

Habitat traits, population structure and host specificity of the freshwater pearl mussel Margaritifera margaritifera in the Waldaist River (Upper Austria)

Biologia ◽  
2013 ◽  
Vol 68 (5) ◽  
Author(s):  
Michael Jung ◽  
Christian Scheder ◽  
Clemens Gumpinger ◽  
Johann Waringer
Keyword(s):  
Host Specificity ◽  
Salmo Trutta ◽  
Rapid Decline ◽  
Margaritifera Margaritifera ◽  
Pearl Mussel ◽  
Freshwater Pearl Mussel ◽  
Fine Sediments ◽  
Upper Austria ◽  
River Stretch ◽  
Brook Char

AbstractIn European streams and rivers, the freshwater pearl mussel (Margaritifera margaritifera L., 1758) faces extinction. This is also true for the Waldaist River, with 20,000 specimens recorded in the early 1990s then Austria’s most important pearl mussel river. Nowadays, there is only a single 320 m stretch with noteworthy mussel densities. During an in-depth survey of this river stretch in 2010, we detected a total of 2,774 specimens. Mussel microhabitats were confined to patches of sand and fine gravel (psammal and akal) at run sections of the river, stabilized by large boulders. Pearl mussels avoided large accumulations of fine sediments. Typically situated at undercut slopes, preferred microhabitats were 0.25–0.50 m deep at baseflow with current velocities (at 40% depth) of 0.2–0.6 m s−1. A comparison of the present stock with data from 1997 revealed a rapid decline in mussel density down to 27%. We also noticed strongly reduced growth and a high mortality of medium age classes. Juvenile mussels were completely lacking. With respect to host specificity in terms of glochidia survival, the brook char Salvelinus fontinalis (Mitchill, 1814), a suitable host in North America, shed glochidia within eight days. In the brown trout Salmo trutta L., 1758, two strains were investigated. Glochidia survival, growth and prevalence were significantly higher in the Danish than in the Austrian hatchery strain.

scholarly journals Higher mortality of the less suitable brown trout host compared to the principal Atlantic salmon host when infested with freshwater pearl mussel (Margaritifera margaritifera) glochidia

2021 ◽  
Author(s):  
Janhavi Marwaha ◽  
Per Johan Jakobsen ◽  
Sten Karlsson ◽  
Bjørn Mejdell Larsen ◽  
Sebastian Wacker
Keyword(s):  
Atlantic Salmon ◽  
Brown Trout ◽  
Host Species ◽  
Salmo Trutta ◽  
The Other ◽  
Margaritifera Margaritifera ◽  
Pearl Mussel ◽  
Suitable Host ◽  
Freshwater Pearl Mussel ◽  
Host Interaction

AbstractThe freshwater pearl mussel (Margaritifera margaritifera) is a highly host-specific parasite, with an obligate parasitic stage on salmonid fish. Atlantic salmon (Salmo salar) and brown trout (Salmo trutta f. trutta and Salmo trutta f. fario) are the only hosts in their European distribution. Some M. margaritifera populations exclusively infest either Atlantic salmon or brown trout, while others infest both hosts with one salmonid species typically being the principal host and the other a less suitable host. Glochidial abundance, prevalence and growth are often used as parameters to measure host suitability, with the most suitable host species displaying the highest parameters. However, it is not known if the degree of host specialisation will negatively influence host fitness (virulence) among different host species. In this study we examined the hypothesis that glochidial infestation would result in differential virulence in two salmonid host species and that lower virulence would be observed on the most suitable host. Atlantic salmon and brown trout were infested with glochidia from two M. margaritifera populations that use Atlantic salmon as their principal host, and the difference in host mortality among infested and control (sham infested) fish was examined. Higher mortality was observed in infested brown trout (the less suitable host) groups, compared to the other test groups. Genetic assignment was used to identify offspring from individual mother mussels. We found that glochidia from individual mothers can infest both the salmonid hosts; however, some mothers displayed a bias towards either salmon or trout. We believe that the differences in host-dependent virulence and the host bias displayed by individual mothers were a result of genotype × genotype interactions between the glochidia and their hosts, indicating that there is an underlying genetic component for this parasite-host interaction.

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