Ecotoxicology of Amphibians and Reptiles. Novel Approaches for Linking Contaminant Effects with Population Declines
Manuel E. Ortiz-Santaliestra, IREC, Spain and Isabel Lopes, Univeridade de Aveiro, Portugal
The session's overall theme was "linking causes and effects through integrated" and "novel approaches in the ecotoxicology of amphibians and reptiles," with a special focus on these aspects that may be related to population declines of these two taxa. These issues are significant in light of increasing evidence and concern about amphibian and reptile population declines, with chemical environmental contaminants being among the major suspected causes. However, the role that contaminants play, either exclusively or in combination with other environmental factors, has rarely been assessed.
The population decline phenomenon triggered intense research activities, and the available information on the ecotoxicology of these two vertebrate classes has considerably increased with the numbers of existing pertinent publications roughly doubling for both taxa only during the last decade. Much work has yet to be conducted to expand our understanding of contaminant effects on amphibians and reptiles, especially the latter. Future scientific challenges include conceptual biosurvey, bioassay, and biomarker development and validation, as well as (not mutually exclusively) micro-pollution, multi-stressor, and effects of targeted research eventually aiming at predicting spatial and temporal exposure and effect cascades through ecosystem structural, functional and trophic integration. Finally, integrating ecosystem approaches into ecological risk assessment is an ultimate requirement to eventually predict spatial and temporal exposure and effect cascades and considering management and remediation measures.
Conclusions and recommendations from the session's presentations covered three different perspectives:
- Ecotoxicity—most presentations focused on the effects of agrochemicals, either alone or in combination, or agricultural input on adult and larval amphibians. Toxicity data of an EDC on tadpole cardiac function was the aim of another talk.
- Tools for ecotoxicological studies—from the biomonitoring perspective, accumulation devices to monitor endocrine disruption potential on the common toad were compared; also, replication of field effects in the laboratory was shown a useful biomonitoring technique. A set of physiological biomarkers analyzed through non-invasive methods were tested in the loggerhead sea turtle.
- Current risk assessment procedures for persistent polar pollutants (PPPs)—based on oral exposure routes, current risk assessment procedures for PPPs are not sufficiently protective for amphibian terrestrial stages because of their high ratio of dermal exposure. Regarding reptiles, current guidelines are useful for most species, but specific information is required for snakes. It is important to obtain more detailed data on species composition and densities, as well as on species ecology, of possible focal taxa. Data from field monitoring may be useful in this task, whereas combining field and laboratory data gives insight into potential threats to species in their actual environment.
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