The invasive red swamp crayfish (Procambarus clarkii) increases infection of the amphibian chytrid fungus (Batrachochytrium dendrobatidis)

Abstract

Emerging infectious diseases are increasingly recognized as a severe threat to wildlife. Chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), is considered one of the most important causes for the decline of amphibian populations worldwide. Identifying potential biological reservoirs and characterizing the role they can play in pathogen maintenance is not only important from a scientific point of view, but also relevant from an applied perspective (e.g. disease control strategies), especially when worldwide distributed invasive species are involved. We aimed (1) to analyse the prevalence and infection intensity of Bd in the invasive red swamp crayfish (Procambarus clarkii) across the western Andalusian region in Spain; and (2) to assess whether the presence of crayfish affects the prevalence and infection intensity of Bd in amphibians of Doñana Natural Space (DNS), a localized highly protected area within the Andalusian region. First, we found that infection prevalence in crayfish guts was 1.5% regionally (four out of 267 crayfish were qPCR positive to Bd, all of them belonging to the same Andalusian population); qPCR positives were histologically confirmed by finding zoosporangia of Bd in gastrointestinal walls of the red swamp crayfish. Second, we found a higher prevalence of Bd infection in DNS (19% for crayfish and 28% for amphibians on average), a place with great diversity and abundance of amphibians. Our analyses showed that prevalence of Bd in amphibians was related to the presence of the red swamp crayfish, indicating that this crayfish could be a suitable predictor of Bd infection in co-occurring amphibians. These results suggest that the red swamp crayfish might be a possible reservoir for Bd,

Virulence and Pathogenicity of Chytrid Fungi Causing Amphibian Extinctions

“…Crustaceans have been proposed as alternative B. dendrobatidis hosts, having demonstrated their capacity to infect tadpoles (79). In Spain, the occurrence of B. dendrobatidis DNA in crayfish guts is related to the presence of B. dendrobatidis in amphibians (89). However, Betancourt-Roman et al (10) could not reproduce B. dendrobatidis persistence in crayfish, bringing into question the role of invertebrates as alternative hosts.…”

First Record of the Alien Species Procambarus virginalis Lyko, 2017 in Fresh Waters of Sardinia and Insight into Its Genetic Variability

“…Nonetheless, there are endemic species of amphibians that may suffer due to the presence of this new invasive alien species in their fresh waters. For instance, Souty-Grosset et al [ 68 ] and Oficialdegui et al [ 69 ] showed that crayfish eat amphibian eggs and tadpoles. Additionally, competition for food could also indirectly reduce amphibian populations, as the grazing activity that crayfish exert on periphyton may lead periphyton-associated invertebrates to disappear [ 70 ].…”

Landscape Connectivity Limits the Predicted Impact of Fungal Pathogen Invasion

“…If the lack of other urodele species and the scarcity of anuran hosts in the Lyciasalamandra range would imply absence of suitable pathogen reservoirs, infection and disease dynamics can be expected to be density dependent [ 26 , 29 ], rendering population extirpation less likely. However, current knowledge does not allow the exclusion of the presence of non-amphibian pathogen reservoirs, which may be biotic (for example invertebrate pathogen reservoirs as proposed for B. dendrobatidis [ 30 , 31 ] or abiotic (long term survival of resistant fungal spores). Abiotic reservoirs should maintain sufficient humidity levels and suitable temperatures for B. salamandrivorans to survive.…”