Invasive fish disrupt host-pathogen dynamics leading to amphibian declines. (December 2022)

• Record Type: Journal Article
• Authors: Rosa, Gonçalo M.; Ayala Botto, Gonçalo; Mitra, Amartya T.; Almeida, João Simões de; Hofmann, Max; Leung, William T.M.; Alves de Matos, António Pedro; Caeiro, Maria Filomena; Froufe, Elsa; Loureiro, Armando; Price, Stephen J.; Owen, Christopher; Rebelo, Rui; Soares, Claudia
• Is Part Of: Biological conservation. Volume 276(2022)
• Publication Date: 2022-12
• Subjects: Ranavirus -- Emerging infectious diseases -- Host-pathogen ecology -- Pathogen emergence drivers -- Invasive species -- Host-pathogen equilibrium; Conservation of natural resources -- Periodicals; Nature conservation -- Periodicals; Ecology -- Periodicals; Environment -- Periodicals; Environmental Pollution -- Periodicals; Electronic journals; 333.9516
• DOI: 10.1016/j.biocon.2022.109785
• Languages: English
• ISSNs: 0006-3207

Abstract

Abstract: Sudden disease outbreaks may not necessarily reflect a recent pathogen introduction but may instead arise from the disruption of a host-pathogen equilibrium. Together with invasive species, emerging pathogens pose significant threats to biodiversity. The dynamics of each stressor have been studied separately, yet rarely when interacting. Using a 40-year dataset, we tested the hypothesis that the introduction of an invasive fish leads to such a disruption, manifested by ranavirosis outbreaks on amphibian hosts. MCP sequencing revealed the historical presence of two major Ranavirus clades, with low prevalence. The introduction of fish was not followed by the emergence of new viruses, but rather by an increase in the prevalence of the strains already present, fitting the 'endemic pathogen hypothesis'. Two decades after the first die-offs, one amphibian species persists in extremely low numbers, but Ranavirus prevalence is closer to the enzootic phase that preceded the outbreaks. Models show that host population collapse and lack of recovery are best explained by the concerted interaction of Ranavirus and invasive fish. We provide robust evidence that invasive species can impact naïve communities by disrupting the host-pathogen balance, exacerbating health threats. This study emphasizes the importance of exploring the historical interactions between multiple stressors to understand population declines. Highlights: Historical presence of Ranavirus was not associated with signs of disease or population declines (EPH); Introduction of invasive species was not followed by the emergence of new viruses; Sudden disease emergence may arise from a disruption of a host-pathogen equilibrium; Invasive species can impact native populations by disrupting host-pathogen equilibria, leading to disease-driven declines; Removal of invasive species decreases the extinction risk of the host population even in the presence of the pathogen.