Invasive crayfishes as a threat to freshwater bivalves: Interspecific differences and conservation implications

Abstract

Freshwater bivalves have suffered major global declines, being the introduction of invasive alien species (IAS) an important, but not well studied, mechanism of threat. This study assessed the predator-prey relationship between two non-native crayfish species (Procambarus clarkii and Pacifastacus leniusculus) and three native (Anodonta anatina, Potomida littoralis and Unio delphinus) and one non-native (Corbicula fluminea) freshwater bivalve species through experiments in laboratory and validation under natural conditions (Sabor River basin, Portugal). All native bivalve species were preyed both in laboratory and in the field; however, both crayfish species were unable to prey C. fluminea. Predation was dependent on crayfish and bivalve species but was not affected neither by crayfish nor bivalve sizes. In the laboratory, the most preyed species by both crayfishes was A. anatina. On average, this species was preyed at least 12% more than other species, when crayfishes had a choice. Similar results were found in the field. We also found signs of competition between both crayfishes, being P. clarkii more dominant and aggressive as this species, on average, manipulated the bivalves 63.6% more times and 24:33 min longer than P. leniusculus, and initiated 55.8% more agnostic bouts. Our results support the idea that P. clarkii and P. leniusculus can affect native freshwater bivalves, but clear interspecific differences were detected. Both crayfishes may have direct and indirect impacts on bivalve populations by increasing mortality or by reducing their fitness. In addition, since both crayfishes do not prey C. fluminea, they offer this IAS another advantage over native bivalves. Given the widespread distribution of both P. clarkii and P. leniusculus and the threatened status of many freshwater bivalves, the dynamics and impacts of this relationship should be taken in account in the implementation of management measures devoted to the conservation of native freshwater bivalves.

Assessment of a terrestrial protected area for the conservation of freshwater biodiversity

“…Other threatened freshwater species listed in the IUCN Red List include the pearl mussel M. margaritifera (Endangered), the freshwater mussel Potomida littoralis (Cuvier, 1798) (Endangered), the Iberian loach Cobitis calderoni Băcescu, 1962 (Endangered), the dragonfly Macromia splendens Pictet, 1843 (Vulnerable), and the Iberian desman Galemys pyrenaicus (É. Geoffroy Saint‐Hilaire, 1811) (Vulnerable). Non‐native invasive species such as the crayfish Pacifastacus leniusculus (Dana, 1852) and the pumpkinseed sunfish Lepomis gibbosus (Linnaeus, 1758) are also present in the study area (Anastácio et al, 2019; Meira et al, 2019; Sousa et al, 2019).…”

From the lab to the river: Determination of ecological hosts of Anodonta anatina

“…The study area is part of the Douro River basin located in northern however, all sites surveyed in this study are at least of 'good ecological status' (Alencoão & Pacheco, 2006;Claro, 2010;Meira et al, 2019;Portilho, 2013;Silva, 2010;Sousa et al, 2012Sousa et al, , 2013 under…”

“…The landscape includes plateaux, mountains, and embedded valleys, with different land uses such as industry, urban development, agriculture, and forestry. The Corgo, Tua, and Tâmega rivers are subjected to higher levels of human disturbance, mainly by pollution from the surrounding industries and urban areas, compared with the Sabor and Paiva rivers(Meira et al, 2019;Sousa et al, 2013Sousa et al, , 2019;…”

Patterns of Distribution of Bivalve Populations in a Mediterranean Temporary River

“…Changes in environmental conditions due to global warming may enable the colonization by new fish, which may not be suitable hosts for some native bivalve's glochidia [41]. Additionally, invasive invertebrate species may predate or compete with U. delphinus [1,9,[42][43][44][45]. Several invasive predatory species are already abundant in this river, such as the Pumpkinseed sunfish (Lepomis gibbosus), the Chameleon cichlid (Australoheros facetus) and the red swamp crayfish (Procambarus clarkii), which may partially explain the low number of juveniles detected during this three-year survey.…”