Conservation of the freshwater pearl mussel (Margaritifera margaritifera) in the river Rede, UK: Identification of instream indicators for catchment-scale issues

Abstract

a b s t r a c tThe freshwater pearl mussel (Margaritifera margaritifera) is declining throughout its entire range. On the river Rede, North-East England, the population has been equally declining and shows no apparent recruitment. The study presented here aimed at characterizing water quality and habitat conditions for pearl mussels to identify possible indicators of pressures on the population and inform a restoration and conservation strategy. Water quality monitoring revealed levels of turbidity and suspended sediments to be above the limit set for functional pearl mussel rivers. Substrate sampling revealed silt was present at all sites. A loss of redox potential between the water column and the substrate occurred at all sites, indicating non suitable conditions for juvenile pearl mussels. These investigations suggest that fine sediment input in the river could be one of the factors preventing the development and survival of juvenile mussels while adults face water quality largely affected by high turbidity and high phosphate load. Restoration strategy for the Rede pearl mussel population should focus mainly on limiting sediment and nutrient input in the river throughout the catchment in order to improve habitat for juvenile pearl mussels. This work highlights the need for a catchment-based approach in order to succeed in the conservation of a fragile species.

Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) differ in their suitability as hosts for the endangered freshwater pearl mussel (Margaritifera margaritifera) in northern Fennoscandian rivers

“…This suggests that more FPM populations will become extinct (Bauer, 1983(Bauer, , 1986Beasley et al, 1998;Cosgrove et al, 2000;Geist, 2010;Geist et al, 2006), and that there may be unidentified factors related to reproduction preventing population recovery. Furthermore, many large European river systems were dammed for hydroelectric production during the 20th century, fragmenting them, reducing river connectivity and thereby preventing migrations of anadromous fish, including Atlantic salmon (Bardonnet & Baglini ere, 2000;Erkinaro et al, 2011;Gosselin, 2015;Kallio-Nyberg, Jutila, Koljonen, Koskiniemi, & Saloniemi, 2010;Parrish, Behnke, Gephard, McCormick, & Reeves, 1998). Unfortunately, the salmonid species used for the compensatory salmonid stocking to mitigate dam impacts are not generally required to be the same as the lost species (Erkinaro et al, 2011;Hiltunen, 2010;Marttila et al, 2014) and, in many rivers, Atlantic salmon have been replaced by hatchery-reared brown trout (Hiltunen, 2010;Luhta & Moilanen, 2006).…”

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

“…The European FPM is now classified as a critically endangered species (Cuttelod et al 2011). The collapse of FPM is generally suggested to be the result of anthropogenic environmental perturbations such as eutrophication, contamination and siltation, which have caused the loss of suitable habitats (Bauer 1983, 1986, 1988, Valovirta 1993, Beasley et al 1998, Cosgrove et al 2000, Dolmen and Kleiven 2008, Scheder and Gumpinger 2008, Geist 2010, Österling et al 2010, Oulasvirta 2010, Varandas et al 2013, Gosselin 2015, Simon et al 2015, Lopes-Lima et al 2016. In addition, river dredging and channelization, as well as loss of host fish via e.g.…”

Pulsed flow-through cultivation of Margaritifera margaritifera: Effects of water source and food quantity on the survival and growth of juveniles

“…The life cycle of M. margaritifera contains critical phases, such as the glochidium larva attaching to Atlantic salmon or brown trout, and the long juvenile stage in the riverbed gravels. Thus, the species is threatened by many anthropogenic environmental disturbances, including pollution, sedimentation, eutrophication, damming, flow changes, invasive salmonids and loss of salmonid host fish (Bauer, 1988;Young, 1991;Young et al, 2001;Ö sterling et al, 2008;Gum et al, 2011;Taskinen et al, 2011;Moorkens & Killeen, 2014;Gosselin, 2015;Salonen et al, 2016).…”