Fish hosts of the freshwater mussel Unio foucauldianus Pallary, 1936

The life cycle of Unio foucauldianus Pallary, 1936, a critically endangered freshwater mussel species (Bivalvia: Unionida), includes a parasitic phase using fish as hosts. Therefore, to develop more efficient conservation strategies it is essential to know which are the suitable fish hosts of U. foucauldianus. In this study, two approaches were used to assess the fish hosts of U. foucauldianus: the determination of infestation rates of fishes under natural conditions through monthly sampling (from January to June) in the Laabid River (Oum Rbia basin) and the N'Fis River (Tensift basin), and artificial infestation in laboratory trials using fish species from both rivers. The natural infestation of fish was detected from February to June, with a peak in May. Fully metamorphosed juveniles were only detected in native fish species, i.e. Luciobarbus ksibi (Boulenger, 1905), Carasobarbus fritschii (Gunther, 1874), Luciobarbus zayanensis Doadrio, Casal-lopez & Yahyaoui, 2016, Labeobarbus maroccanus (Gunther, 1874), and Luciobarbus magniatlantis (Pellegrin, 1919). The two non-native fish species used do not function as effective hosts. Given the increasing human pressure on native fish species in the Mediterranean biodiversity hotspot, including the increased number of non-native fish introductions, urgent conservation measures are discussed for this and other freshwater mussel species.The authors would like to express their thanks to the High Commission for Water and Forests (HCEFLCD) for granting permission to use electrofishing in the Moroccan basins. This study was conducted within the scope of the project ‘Biodiversity and conservation of the critically endangered freshwater mussels in Morocco: ecogeographic, genetic and physiological information’, funded by the Mohamed Bin Zayed Species Conservation Fund (ref. 15256799), and the project ‘Breeding the most endangered bivalve on Earth: argaritifera marocana’, funded by the IUCN SOS (Save our Species) fund (ref. 2015B‐015)

The role of human activities in the transmission of stomach flukes Paramphistomum microbothrium (Fishoeder, 1901) (Trematoda: Paramphistomatidae) in Tessaout amont irrigation scheme, Central Morocco

Une prospection menée au niveau des différentes structures du réseau d’irrigation dans la région de Tessaout Amont a montré l’existence de neuf espèces de mollusques d’eau douce appartenant à cinq familles. Les canaux d’irrigation traditionnels sont des sites de transmission de la schistosomose à Schistosoma haematobium à l'homme et de la distomatose à Fasciola hepatica chez les ovins et les caprins du Haouz. Plus récemment, la transmission de la paramphistomose a été également rapportée pour la première fois dans le Haouz au Maroc. La présente étude montre que l’infestation de Bulinus truncatus hôte intermédiaire de Paramphistomum microbotrium s’effectue dans des siphons inaccessibles au bétail qui en constitue l’hôte définitif. Il s’est avéré que les oeufs du parasite sont mis en contact du mollusque suite au rinçage des viscères de ruminants abattus par les bouchers et par les riverains dans l’eau des canaux et des siphons. Les implications de ce résultat sur les possibilités de lutte contre cette maladie sont discutées

Freshwater conservation assessments in (semi-)arid regions: testing river intermittence and buffer strategies using freshwater mussels (Bivalvia, Unionida) in Morocco

The IUCN Red List assessments are essentially based on population trends and range, namely Area of Occupancy (AOO) and Extent of Occupancy (EOO). Range estimations are based on fixed grids, but this is likely inappropriate for species living in river networks. Furthermore, AOO and EOO are measured using the whole hydrographic network, therefore disregarding temporary sections, which is particularly problematic in arid and semi-arid regions. Here we mapped the permanent hydrographic network of Morocco using satellite imagery, complemented with field surveys to collect samples for molecular analyses of the five freshwater mussel species present and assess their distribution. The phylogeographic patterns are described for each species and used to identify priority areas and evolutionary significant units for conservation. Permanent hydrographic river sections represent only 18.3% of the whole hydrographic network. A north-to-south gradient of genetic diversity, species richness and distribution range was found, being coherent with water availability and river intermittence. Isolated evolutionary units were detected in southern basins that should also receive particular attention in conservation planning. We propose the mean river width multiplied by the extent of the river network as the best and the most adequate way to estimate both EOO and AOO. Given the worldwide degradation of freshwater systems and biodiversity, an accurate (re)assessment of species conservation status supported with maps of intermittent water bodies will be essential for prioritizing and guiding conservation actions and management plans, especially in arid and semi-arid regions.This work was partially supported by the Portuguese Foundation for Science and Technology (FCT) under grant SFRH/BD/115728/2016 (MLL) and grant SFRH/BD/137935/2018 (AGS). This research was developed under ConBiomics: the missing approach for the Conservation of freshwater Bivalves Project N° NORTE-01-0145-FEDER-030286, co-financed by COMPETE 2020, Portugal 2020 and the European Union through the ERDF, and by FCT through national funds. This study was additionally conducted within the scope of project “Biodiversity and conservation of the critically endangered freshwater mussels in Morocco: ecogeographic, genetic and physiological information”, funded by Mohamed bin Zayed Species Conservation Fund (Reference 15256799) and project “Breeding the most endangered bivalve on Earth: Margaritifera marocana”, funded by IUCN SOS save our species fund (Reference 2015B-015). Official capture and sampling licenses were issued by the Université Cadi Ayyad (Faculté des Sciences, Semlalia, Marrakech, Maroc)

The conservation status of the world's freshwater molluscs

With the biodiversity crisis continuing unchecked, we need to establish levels and drivers of extinction risk, and reassessments over time, to effectively allocate conservation resources and track progress towards global conservation targets. Given that threat appears particularly high in freshwaters, we assessed the extinction risk of 1428 randomly selected freshwater molluscs using the IUCN Red List Categories and Criteria, as part of the Sampled Red List Index project. We show that close to one-third of species in our sample are estimated to be threatened with extinction, with highest levels of threat in the Nearctic, Palearctic and Australasia and among gastropods. Threat levels were higher in lotic than lentic systems. Pollution (chemical and physical) and the modification of natural systems (e.g. through damming and water abstraction) were the most frequently reported threats to freshwater molluscs, with some regional variation. Given that we found little spatial congruence between species richness patterns of freshwater molluscs and other freshwater taxa, apart from crayfish, new additional conservation priority areas emerged from our study. We discuss the implications of our findings for freshwater mollusc conservation, the adequacy of a sampled approach and important next steps to estimate trends in freshwater mollusc extinction risk over time

The Moroccan stygobiont genus Heideella (Gastropoda, Prosobranchia: Hydrobiidae)

The new genus Atebbania is described for a new hydrobiid species, A. bernasconii, which lives in groundwaters of southern Morocco. Of the Hydrobiidae genera with known shell and anatomy Moitessieria is the closest to Atebbania. The two share the following characters: shell elongate; teleoconch surface with evident microsculpture; seminal receptacle absent. Atebbania is distinguished from Moitessieria by: shell ovate; penis with a) apical stylet, b) one lobe bent downward on left (inner) side and c) penial duct running near the right (outer) side; posterior end of foot indented. Atebbania bernasconii n. sp., lives in a limited area, the Tiznit plain in southern Morocco. Other stygobiont hydrobiids from other areas of Morocco are currently being studied. None of them appears to be closely related to A. bernasconii or to the species of Moitessieria

Croissance et reproduction de

Sous des conditions semi-naturelles, les diminutions de la croissance et la fécondité chez Bulinus truncatus sont d'autant plus grandes que la densité est forte, aussi bien dans les situations de compétition interspécifique avec Melanopsis praemorsa que dans les situations de compétition intraspécifiques. M. praemorsa (Mp) influence considérablement les traits de vie de B. truncatus (Bt). Pour un rapport de densité Bt/Mp de 1/1, la présence de M. praemorsa stimule de façon significative à la fois la croissance et la fécondité de B. truncatus. Pour des rapports Bt/Mp de 1/3, 1/8 et 1/17, la présence de M. praemorsa inhibe la croissance mais continue de stimuler la fécondité de B. truncatus. Cela est à mettre en relation avec le comportement différent observé chez les M. praemorsa lors de variations de densités ; alors que pour de faibles densités, les niches trophiques des deux espèces sont différentes, pour de fortes densités les M. praemorsa se dispersent dans le milieu, le recouvrement des niches entre les deux espèces devient plus important et ceci entraîne un accroissement de la compétition interspécifique. L'ensemble des résultats montre que l'implantation et la dispersion de M. praemorsa à des densités élevées dans les canaux d'irrigation pourraient jouer un rôle dans le déclin des populations de B. truncatus dans les sites de transmission de Schistosoma haematobium dans la région du Haouz au Maroc

The first Margaritiferidae male (M-type) mitogenome: mitochondrial gene order as a potential character for determining higher-order phylogeny within Unionida (Bivalvia)

The unionid family Margaritiferidae, comprising 12 extant species, is widely distributed across the northern hemisphere in North America, Europe and Asia (Bolotov et al., 2016). Most species in this family have dramatically declined over the last century, with nine of the 12 species assessed as threatened in the most recent IUCN Red List (IUCN, 2016). Among these is the Moroccan pearl mussel Margaritifera marocana (Pallary, 1918), considered one of the 100 most threatened species on the planet (Baillie & Butcher, 2012). This species is now restricted to two small streams in the Oum Er Rbia and Sebou basins and conservation measures are urgently needed (Sousa et al., 2016). Beyond the conservation concern, Unionida are also biologically interesting. They present an unusual mechanism of mitochondrial inheritance called doubly uniparental inheritance (DUI), in which all individuals have the typical maternally transmitted mtDNA (F-type), but the males possess in their germ cells a paternally inherited mtDNA instead (M-type) (Zouros et al., 1994; Breton et al., 2009). So far, DUI has been observed in over 100 species from four bivalve orders (Gusman, Azuelos & Breton, 2017), including three families within Unionida, i.e. Unionidae, Hyriidae and Margaritiferidae (Walker et al., 2006). However, to date, no whole M-type mitogenome has been published for any species belonging to the last two of these families.This work was partially supported by the Mohamed bin Zayed Species Conservation Fund under project ‘Biodiversity and conservation of the critically endangered freshwater mussels in Morocco: ecogeographic, genetic and physiological information’ (Reference 15256799), by the IUCN SOS Save Our Species fund under project ‘Breeding the most endangered bivalve on Earth: Margaritifera marocana’ (Ref. 2015B-015) and by the Portuguese Foundation for Science and Technology (FCT) under grants SFRH/BPD/70654/2010 (M.M.F.) and SFRH/BPD/108445/2015 (E.F.)