Metal contents in house geckos (Squamata: Gekkonidae) from industrial and urban areas of southern Tamaulipas, Mexico and western Andalucía, Spain, may reflect airborne metal pollution

ABSTRACT

House geckos share living quarters with humans in the tropical and subtropical regions inhabited by these reptiles. Gecko behavior, biological traits, continuous exposure to suspended particulate matter 0 µm in diameter (PM₁₀) and dust, as well as status as exotic species, motivated the choice of these species to examine environmental exposure to ambient air pollutants, in particular metals, and subsequent accumulation in these organisms. One part of the study was conducted in Tamaulipas (Mexico) where Hemydactylus frenatus is abundant in urban and industrial environments, the other part was conducted in Andalucia (Spain) where Tarentola mauritanica is found in similar environments. Adult geckos were collected on buildings in locations affected by various air pollution sources. For both species, higher metal contents were observed in whole-body (including digestive tracts) analysis and were markedly different between collection sites. Contents in tails, digestive tracts, and carcasses without digestive tracts were not correlated. Based on contamination factor values, bioaccumulation in H. frenatus tissues occurred for 12 of the 15 metals analyzed. Data suggest that H. frenatus might serve as a biomonitor for Cu, Ni, Pb, Cr, Li, and V, whereas T. mauritanica might be a biomonitor for Cu, Ni, Pb, and Cr. To our knowledge, metal contents for H. frenatus are reported here for the first time. House gecko data could be integrated into a highly representative monitoring system and health risk assessments related to air quality in residential areas.

KEYWORDS:

• Bioindicators
• air pollution
• Hemidactylus frenatus
• Tarentola mauritanica
• urban indicators
• reptiles

Acknowledgments

Luisiana Morales-Zamudio is grateful for her postgraduate fellowship to CONACyT, COFAA-IPN, and SIP-IPN. The authors are thankful for the financial support provided by Instituto Politécnico Nacional through the SIP projects: 2022-0668, 2022 0671 and COFAA. This work has been also funded by CONACyT through the CB-2006 and SNI-CONACyT. We are grateful to Jesus de la Rosa Diaz (University of Huelva) for his support during the collection of specimens in Spain, metal analysis, and other chemical analyses. We would also like to thank David Lecusay Jr. and Esmirna Cantu (School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley) for preparing Figure 1 and for the original drawing of the geckos, respectively.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

All the data generated and analyzed during this study are available from the corresponding author upon request.

Ethical approval

Handling of geckos complied with the norm NOM-062-ZOO-1999 in Mexico and Real Decreto 1201/2005 in Spain, for use and care of research animals, when applicable.

Authors contribution and consent to participations

Alejandro Fierro-Cabo provided the research idea and collected specimens in the reference site. Luisiana Morales-Zamudio conducted the field and laboratory work and obtained the data. Alejandro Fierro-Cabo, Luisiana Morales-Zamudio, Md Saydur Rahman and Miguel Antonio Domínguez-Crespo analyzed the data. Alejandro Fierro-Cabo and Md Saydur Rahman drafted the manuscript. Alejandro Fierro-Cabo, Luisiana Morales-Zamudio, Md Saydur Rahman edited and Miguel Antonio Domínguez-Crespo reviewed the manuscript. Alejandro Fierro-Cabo and Miguel Antonio Domínguez-Crespo validated, provided resources and funding acquisition.

Additional information

Funding

This study was funded by Instituto Politécnico Nacional through Secretaria de Investigación y Posgrado, and Consejo Nacional de Ciencia y Tecnología CONACYT, México.