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

Salonen, JouniThe role of salmonid fishes in conservation of the endangered freshwater pearl mussel (Margaritifera margaritifera) Jyväskylä: University of Jyväskylä, 2016, 48 The abundance of freshwater pearl mussels (Margaritifera margaritifera) has declined widely during the past century, and new conservation initiatives are needed. This thesis focused on the relationship between M. margaritifera and its salmonid host required for reproduction of this species. First, by exposing fish experimentally to glochidium larvae of M. margaritifera, different M. margaritifera populations were shown to demonstrate strong differences in their ability to parasitize different salmonid species. Atlantic salmon was clearly a better host for mussels in large river channels, whereas in small headwater tributaries brown trout was the best, or the only suitable, host. These findings provide a previously unrecognised explanation for the collapse and the lack of recruitment especially of the salmon-specific M. margaritifera populations; a high proportion of large salmon rivers were dammed for hydropower production in the 1960s, which prevented the migration of salmon and thus left M. margaritifera without the appropriate host in these rivers. Furthermore, an invasive salmonid, brook trout, was widely introduced to small tributaries above the dams in the past, but in this study was shown to be an unsuitable host for M. margaritifera. Thus, and due to the tendency of brook trout to replace native brown trout, the spread of brook trout is an additional threat to M. margaritifera. An indication of local adaptation of M. margaritifera, i.e. higher infectivity in sympatric salmonid host strain than in allopatric populations of the same species, was also detected. Finally, a new, nondestructive approach to search for M. margaritifera populations, involving electrofishing and quick visual examination of the gills of captured salmonids, revealed the occurrence of 3 previously unknown populations. The results of this thesis highlight the importance of taking into account the roles of salmonid fish in future efforts to search, protect and restore freshwater pearl mussel populations.

Section: Suitability Of Brook Trout As a Host For The European Freshwsupporting

confidence: 91%

Section: Suitability Of Brook Trout As a Host For The European Freshwsupporting

confidence: 68%

Section: The Interactions Between the Freshwater Pearl Mussel And Hosmentioning

confidence: 58%

Section: Habitat Preferences and Life Cycle Of The Freshwater Pearl Mmentioning

confidence: 99%

Section: Cage Experimentsmentioning

confidence: 99%

See 3 more Smart Citations

An alien fish threatens an endangered parasitic bivalve: the relationship between brook trout (Salvelinus fontinalis) and freshwater pearl mussel (Margaritifera margaritifera) in northern Europe

Salonen

Marjomäki

Taskinen

2016

The impact of publication on freshwater pearl mussel conservation: To conceal or to reveal the location of threatened habitats?

Popov

2020

1.The freshwater pearl mussel, Margaritifera margaritifera, is a threatened species. One of the threats faced by this species is direct extermination by poachers, and therefore some researchers conceal information on the locations of pearl mussel habitats. For example, some researchers do not publish the names of the rivers where pearl mussels occur, whereas other researchers do. 2.Concealing the names of rivers containing pearl mussels makes them unknown not only to potential offenders but also to administrators, nature conservation practitioners, and ordinary citizens. As a result, no protection measures are undertaken, which is all the more regrettable as damage to pearl mussel habitats can occur accidentally. 3.Concealing details of the location of pearl mussel habitats in publications has an adverse impact on the work of specialists, as they do not have access to enough information to study and analyse the biology and distribution of these molluscs. 4.One river with pearl mussels in the Gulf of Finland was initially described anonymously (as ‘River B’). Unfortunately, the river was subject to severe human impact, and the largest aggregation of pearl mussels was almost exterminated in the process of constructing a new electric supply line. 5.Concealing information on pearl mussel habitats in the Russian section of the Baltic Sea basin was also shown to have been a poor decision. Although the threat from potential poachers was insignificant because of the low commercial value of pearl mussels, the authorities remained uninformed about the existence of valuable habitats. 6.The question of whether the locations of pearl mussel habitats should be concealed or revealed in scientific publications does not have an unambiguous answer and should be considered on a case‐to‐case basis; however, the cases for which disclosure is reasonable seem to be more numerous.

Stable isotopes reveal the importance of terrestrially derived resources for the diet of the freshwater pearl mussel (Margaritifera margaritifera)

Brauns

Berendonk

Berg

et al. 2021

The freshwater pearl mussel (FPM) is among the most endangered freshwater species worldwide. The few remaining populations suffer from low recruitment rates and are subject to habitat fragmentation, pollution, siltation, decline or loss of host fish populations, and climate change. Successful conservation strategies for FPM require a holistic understanding of its ecological requirements, life history, population dynamics, and habitat prerequisites. Although habitat requirements are well described, food requirements at different life stages have received less attention. Stable isotope analyses of FPM and potential food resources in three German streams were combined with mixing model analysis to quantify organic matter resources assimilated by juvenile (first year after encystment from host fish) and semi‐adult (10 years old, immature) individuals. There were only slight differences in dietary contributions between the two life stages, and terrestrial particulate organic matter and benthic organic matter contributed substantially to the diet. Tissue type was more important in explaining variation in dietary contributions than individual variation for semi‐adult FPM. The strong reliance on terrestrial resources sheds new light on the functional role of unionid mussels and the connection of streams to their riparian area. The dependence of FPM on terrestrial resources also emphasizes the need for a stronger focus on the restoration and protection of intact riparian areas, including wetlands with their specific vegetation, when planning conservation and management strategies for threatened FPM populations.