Challenging exploration of troubled waters: a decade of surveys of the giant freshwater pearl mussel Margaritifera auricularia in Europe

Self Cite

The giant freshwater pearl mussel Margaritifera auricularia (GFPM) is one of the most endangered bivalve species in the world. Originally occurring in many European rivers, the GFPM is a relict now restricted to a few ageing populations in France and Spain in which natural reproduction is almost absent. Like most unionoid mussels, the GFPM needs host fish for the development of their parasitic larvae (glochidia). The European sturgeon (Acipenser sturio), the only known native host fish of the GFPM in France, is essentially extinct. Therefore, the aim of this study was to identify other hosts that could be responsible for the few cases of recent recruitment. Natural infestation of wild fishes in three French rivers was assessed to identify potential hosts of M. auricularia, while artificial infestation experiments were conducted on the sea lamprey (Petromyzon marinus) and the wels catfish (Silurus glanis) to determine their compatibility as hosts. Among the 29 fish species assessed for natural infestation, only the three‐spined stickleback (Gasterosteus aculeatus) and the European eel (Anguilla anguilla) carried M. auricularia glochidia. In the artificial infestation experiments, living juvenile mussels were collected from both P. marinus and S. glanis. The number of juveniles collected from a single P. marinus specimen (13,827) suggests that this species is a highly efficient host. As with previously known hosts, newly identified ones also appear to have a relationship with marine environments. The present findings suggest that P. marinus has played a key role in preventing the total extinction of M. auricularia in France, and indicate the potential use of P. marinus in conservation strategies aimed at reintroducing or stabilizing populations of this rare mollusc.

Section: Introductionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

“…Distribution of P. marinus modified from Kottelat and Freyhof () and NatureServe (). Distribution of M. auricularia modified from Prié et al ()…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An unexpected host for the endangered giant freshwater pearl mussel Margaritifera auricularia (Spengler, 1793) as a conservation tool

Soler

Boisneau

Jugé

et al. 2019

Self Cite

Captive breeding of Margaritifera auricularia (Spengler, 1793) and its conservation importance

Nakamura

Elbaile²,

Salinas³

et al. 2019

Margaritifera auricularia is one of the most endangered freshwater mussels (Bivalvia, Unionida) in the world. Since 2013, the abundance of this species in the Ebro River basin (Spain) has sharply declined, driving the species to the verge of regional extinction. Therefore, any management measures that might facilitate the recovery of this species would be essential for its conservation. During 2014–2016, captive breeding of M. auricularia allowed the production of >106 juveniles, out of which 95% were released into the natural environment, and 5% were grown in the laboratory under controlled conditions. The aim of this experimental work was to establish the best culture conditions for the survival and growth of M. auricularia juveniles in the laboratory. The experiment was divided into two phases: phase I, in which juveniles recently detached from fish gills were cultured in detritus boxes until they reached a shell length of 1 mm; and phase II, in which these specimens were transferred to larger aquaria to grow up to 3–4 mm. The best experimental conditions for juvenile survival and growth corresponded to treatments in glass containers at a density of 0.2 ind. L−1, using river water, with added substrate and detritus, enriched with phytoplankton, and avoiding extra aeration. The highest survival and growth rates attained, respectively, values of c. 60% at 100 days and 2.56 mm in shell length at 30–32 weeks. This is the first study to report on the long‐term survival and growth of juvenile M. auricularia in the laboratory, providing essential information in order to implement future conservation measures addressed at reinforcing the natural populations of this highly threatened species in European water bodies.

Freshwater mussels in Mediterranean‐climate regions: Species richness, conservation status, threats, and Conservation Actions Needed

Benson

Stewart

et al. 2021

The five global Mediterranean‐climate regions are experiencing alarming rates of freshwater biodiversity loss. Although freshwater mussels are recognized as important functional components in aquatic ecosystems, and are among the most threatened faunal groups globally, there has been no synthesis of the plight of this group within these regions. Data from the International Union for Conservation of Nature (IUCN) Red List were reviewed to compare the conservation status, threats, and conservation actions needed for freshwater mussel species occurring in Mediterranean‐climate regions (med‐mussels) with those of other freshwater mussel species globally. The first comprehensive catalogue of med‐mussel species was compiled using existing taxonomic literature. There are 41 med‐mussel species, 30 of which occur in the Mediterranean basin. Many regions have just a single species, and regions where multiple species occur generally only have between one and four species per river basin. Med‐mussel species are almost twice as likely to be ‘Imperilled’, are affected by 2.4 times more threats, and require 3.5 times more conservation actions than non‐med mussels. In many cases, the exact threats have not been identified. In combination with low species richness, this level of imperilment means that Mediterranean‐climate regions are at risk of losing the benefits that mussels provide to broader ecosystem functioning. The conservation of med‐mussels can be improved by increasing our knowledge of species distributions, including the identification of cryptic species and significant management units, through population genetic work. In addition, recognizing the potential of ‘novel’ habitats and refuge areas could augment the management of this important functional group.