Development of an Ecological Interaction Model: Evaluation of Acute Infection of Ceratophrys ornata Eggs With Different Oomycete Species

OSER FEDERICO LEANDRO; NATALE GUILLERMO SEBASTÍAN; SALGADO COSTA CAROLINA; STECIOW MÓNICA

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

LATU, Montevideo

The study of toxic effects on ecological interactions is becoming increasingly important in the field of ecotoxicology. It requires the development of a model that is more ecologically relevant than individual or subindividual models. Interactions between species can occur in several ways, one of which is parasitism. Oomycetes, also known as aquatic molds, are a group of microorganisms belonging to the Straminipila kingdom that are infectious parasites for some amphibian species. In the present study, the infection of Ceratophrys ornata (Anura: Ceratophryidae) eggs with 15 different species of oomycetes isolated from aquatic environments surrounding the city of La Plata (Buenos Aires Province - Argentina) was evaluated. Two acute infection assays were performed in multiwell plates. One with unfertilized eggs and the other with fertilized ones. In both assays eggs were exposed to spore suspensions of known concentration, without medium renewal and under controlled laboratory conditions (25º ± 2, photoperiod: 16:8 L:O). The results in the unfertilized eggs indicate that the albuminous structure covering C. ornata eggs is a favorable substrate for the development of all oomycete species tested. Significant effects were also observed on survival, growth, development and morphology of hatched C. ornata embryos from fertilized eggs. The oomycetes identified as more pathogenic were: Achlya sp., Brevilegnia sp. and two Saprolegnia spp. In addition, the response to infection was found to differ among the different oomycete species, suggesting that future tests should be considered species-specific. The results obtained also suggest that infection of C. ornata eggs with oomycetes is a useful model for ecotoxicology to study the effects of contaminants on this ecological interaction. The next step will be to include a fungicide in the proposed model.