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Eavesdropping on the tropics: assessment of climate change impacts on amphibians through passive acoustic monitoring

Periodic Reporting for period 1 - EAVESTROP (Eavesdropping on the tropics: assessment of climate change impacts on amphibians through passive acoustic monitoring)

Reporting period: 2016-01-01 to 2017-12-31

Current climate change is a major threat for biodiversity conservation. Global warming has caused shifts in species distributions, the timing of biological processes, and may be involved in regional and major extinctions. Providing original knowledge relevant to predict, mitigate, and perhaps prevent these impacts is a key and urgent challenge for current biology.
The effects of climate change are considered to be significantly deleterious in amphibians, which are the most endangered group of vertebrates, with more than 40% of its species classified as threatened. According to emerging hypotheses, tropical amphibians are prone to considerably higher risk of decline by environmental warming than temperate zone amphibians. Therefore, in addition to other threats, climate change is likely exacerbating the vulnerability of amphibian diversity, particularly in the world’s most biologically diverse region.
Acoustic communication plays a prominent role in mate choice and reproduction in amphibian anurans, and hence is crucial for individual fitness. However, sound production is strongly influenced by environmental factors and few studies have explored whether recent climate change may compromise the performance of calling activity in amphibians.
Animal sounds are generally species-specific and therefore embed a signature of animal diversity. Based on this principle, new acoustic technologies have recently developed to automatically monitor animal populations and communities. These powerful tools provide non-invasive and inexpensive methods expected to facilitate biodiversity assessments at large spatio-temporal scales.
Therefore, the overall objectives of the present project are the following:
ASSESS the effects of climate change on reproductive behaviour and geographical distribution of amphibian species and communities through a new approach based on the integration of bioacoustics and biogeography
DEVELOP, TEST and DISSEMINATE new acoustic techniques for non-invasive biodiversity assessments and the study of animal species and communities
CONTRIBUTE to public awareness of the threat of climate change as well as to environmental policies aimed at the mitigation or prevention of its impacts on biodiversity
The study species and sites were first selected, from more than a thousand amphibian anurans and all around Brazil and surrounding countries, by a detailed analysis based on six taxonomic and five biogeographic criteria. This analytic process led to identify 37 study species and seven study sites across Brazil, Bolivia and French Guiana. The study sites corresponded to four biomes (Atlantic Forest, Cerrado Forest, Pantanal, and Amazon Rainforest) and were located at the climatic extremes of the study species. Data collection for each site was conducted by using passive acoustic monitoring, a new automated and non-invasive recording technique, in order to register calling activity of the study species and communities as well as weather conditions during one entire breeding season. This automated method has been proposed because showing diverse advantages, such as reducing disturbances from the presence of observes, obtaining larger and simultaneous sampling data or enhancing species detection.
Thereby, data collection provided above 400 thousand recordings (>2 TB) and additional metadata corresponding to a year of automated monitoring for all study sites. For analysing this big data set, an ad-hoc semi-automated sound recognition procedure was developed. This procedure allowed determining the daily and seasonal patterns of calling activity of each study species and associated them with specific weather conditions.
Overall, the daily and seasonal patterns of calling activity were found to be species-specific, with larger differences in seasonal patterns than in daily ones between populations located at climatic extremes. This suggests that the study species are more prone to shifts in their breeding phenology than in their day-night cycle of activity. On the other hand, in comparison with temperate zone anurans, tropical anurans showed calling activity at more restricted ranges of temperature and relative humidity, which meets the established predictions. Hence, our findings indicated that tropical anurans are more vulnerable to climate changes during their breeding and calling activity than temperate zone species.
Finally, the information collected was expanded into a larger temporal and spatial scale, following a biogeographic approach, in order to predict the impacts of the current climate change on phenology and geographic distribution of the study species. This analytic procedure was first tested in temperate zone anurans using previous data sets. According to a severe climate change scenario for 2050, our findings pointed out that shifts in phenology due to climate change are expected to be more probable than shifts in geographic ranges in temperate zone anurans. The phenology of the breeding and calling activity of the study species was predicted to be altered by climate change, showing prominent advances in comparison with the current breeding season.
The present project was characterized by a strongly innovative approach, based on the integration, for the first time, of two complementary scientific disciplines: bioacoustics and biogeography. This has led to the development of new techniques and methodologies in passive acoustic monitoring, signal processing and biogeographic analysis, as a starting point for new scientific pathways, which are addressed to better understand critical environmental aspects of contemporary societies: climate change and biodiversity conservation.
The action has had a prominent impact on the researcher's career, despite of the short period of implementation of the project. As a result of the MSCA, the fellow achieved a position in new institution in order to develop his research line, strongly reinforcing of his status as researcher and enhancing his potential and future career prospects. Even though the MSCA was early terminated, the fellow will continue the research line designed in the action, with new projects aim at progressing in this promising scientific area.
The implementation of the MSCA has enabled the creation of an international network of scientific collaboration between research teams from institutions in Brazil, French Guiana, Spain, etc., oriented to the development of new acoustic techniques for biodiversity assessment and conservation. The strengthening of these international relationships has brought new joint proposals for international calls in several countries, three of them already accepted, with the purpose of continuing the research line initiated with the MSCA.
The implementation of the action and the consequent reinforcement of the researcher career on these aspects have therefore contributed to the leadership status of Europe on the search of solutions for current environmental challenges. The MSCA has provided results and new scientific techniques and approaches to predict, buffer, and perhaps ameliorate the global decline of the most endangered group of vertebrates and in the world’s most biologically diverse region, and hence encouraging the central role of the European society in global environmental protection.
View of Atlantic Forest in the Parque Estadual da Serra do Mar (São Paulo, Brazil)
Temporary pond in the Parque Estadual da Serra do Mar (São Paulo, Brazil)
Automated sound recorder installed in the Parque Estadual da Serra do Mar (São Paulo, Brazil)
Male of Hypsiboas bandeirantes
Male of Aplastodiscus spp.
Male of Hypsiboas faber in front of a data logger registering air temperature and relative humidity