Alguns fatores ambientais relevantes na determinação de áreas adequadas para a conservação de Atelopus hoogmoedi Lescure, 1974 (Anura: Bufonidae) no Escudo das Guianas

Abstract

Determining effects of environmental variation in species occurrence and identifying factors responsible for fluctuation in local abundance are crucial issues in evaluating species conservation. Such studies can assist the design of conservation strategies for threatened taxa. Atelopus is one of the most threatened frog genera in the Americas and, besides chytridiomycosis, many species in Amazonia lowland are under significant pressure from anthropogenic activities that threaten their survival. We investigated how landscape heterogeneity influences the occurrence patterns and density variation of Atelopus hoogmoedi at the eastern boundary of the Guiana Shield. We sampled 26 riparian plots that measured 250 m by 7 m on banks of second- to fourth-order stream along Araguari River basin, in the eastern Brazilian Amazon region. Fieldwork was conducted during the rainy season from March 2021 to September 2021 and December 2021 to February 2022, and plots were distributed to represent basin wider landscape heterogeneity. Atelopus hoogmoedi has a patchy distribution, being associated with dense forests (biomass above 300 megagramme of carbon per hectare or MG C ha-1) in uplands (> 100 m) with low precipitation seasonality. Density of individuals varied in response to subtle changes in stream physicochemical characteristics, being positively associated with third- and fourth-order streams (discharge between 3.6 and 17 m3/s) with neutral pH (between 4 and 7). The landscape and habitat associations observed have the potential to inform conservation management for A. hoogmoedi, including establishment of protected areas where suitable habitat exists. Furthermore, we suggest A. hoogmoedi population fluctuations could be monitored in permanent riparian plots across multi-year periods to measure the impact of any strong changes in climate and landscape.