Ribeiro da Água Forte, metal contaminated effluent used on ecotoxicological assays. This water body drains an area of mining slug, which have for decades have been a source of acid waters impacting groundwater and soils, including P. perezi habitat in Aljustrel. Portugal. Photo: Sara Costa.

Ecotoxicological Studies as a Tool on Amphibians’ Disease Risk Assessment


Amphibian natural populations are strongly affected by pathogenic agents. The risk of disease is dependent on the pathogen environmental conditions, capacity of infection and the host’s susceptibility to disease. Changing the environment, in which amphibians thrive, modifies the distribution, increases the risk for diseases transmission and even affects the ecology of populations. Therefore, chemical contamination can act as stressor both for host and/or pathogens and can change the host-pathogen’s dynamics. Saprolegnia spp. has been responsible for large economic losses in aquaculture industry. Furthermore, it frequently causes infections and population losses in amphibians. The interaction of environmental changes with pathogen has been assigned as a reliable explanation for the emergence of infections (in places where they were not previously reported). Hence, it is important to understand the effects that environmental changes can have on pathogens and clarify potential interactions between disease and environmental changes. To study this subject, generate new knowledge and promote a more accurate conservation of amphibians, ecotoxicological methodologies will be carried out. Alarming projections for sea levels rise foresee the salinization of low-lying coastal freshwater ecosystems (due to the intrusion of seawater), which will affect ecologically important biodiversity hotspot (which usually holds high amphibian’s diversity). It is also aimed to study the effects of metal contamination because it is almost ubiquitous and correlated to anthropogenic activity. Therefore two chemical perturbation scenarios will be studied: increased salinity (NaCl will be used as a surrogate of seawater) and metal contamination (a mining effluent contaminated with several metals and where P. perezipopulations were observed will be used). Data from the ongoing projects, showed that potentially, metal contamination can drive genetic erosion and changes on Pelophylax perezi skin microbiome composition.

Lagoa das Braças, a shallow freshwater coastal lagoon, habitat of P.perezi and other amphibian species suchHyla arborea, Discoglossus galganoi and Bufo bufo. Quiaios, Portugal. Photo: Sara Costa.

The main objective of this project is to assess the role of environmental alterations (metal-contamination and salinization) driving amphibian populations to become more sensitive to infectious agents like Saprolegnia sp.. To achieve this objective four specific objectives will be tackled: a) evaluate the effects of metal contamination and salinization on the pathogen agent Saprolegnia and in early life stages of the amphibian species; b) assess the existence of skin bacteria that potentially can inhibit Saprolegnia growth; c) assess the effects of metal contamination and increased salinity on bacteria that inhibit Saprolegnia growth; d) assess the infection prevalence on eggs and tadpoles, by Saprolegnia molt under the specific scenarios of non-effect levels (to amphibians) of salinization and metal contamination.

Exposure assay with P. perezi tadpoles. Photo: Emanuele Fasola.

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Bact x Saprolegnia

Antagonistic assay between a bacterial strain isolated from P. perezi skin and Saprolegnia sp. showing strong inhibition against the pathogen.Photo: Sara Costa.


Project Description
Ecotoxicological studies as a tool on amphibians’ disease risk assessment.

Target Species
The project is focused on Pelophylax perezi as an alternative reliable proxy to amphibians’ species that, because of their conservation status, cannot be used in ecotoxicological studies.

IMG_1265Pelophylax perezi. Photo: Cátia Santos.

Team Members
Sara Costa, Emanuele Fasola, Barbara Santos, Ariana Moutinho, Nuno Costa and Isabel Lopes

Partner Organizations
CESAM & Biology Department of Aveiro University (dBio-UA)

Funding Needs
If you would like to further support this project or invest in the Amphibian Survival Alliance’s Seed Grant program please contact Candace M. Hansen-Hendrikx, Director of Communications and Partnerships.

Your donation will make an immediate, real, and lasting impact. As a global alliance with partners generous enough to cover our operational costs, we are able to channel 100% of your donations directly to helping save these amphibians.

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