Bioaccumulation of potentially toxic trace elements (As, Cd, Hg, In, Ni, Pb, Se, Zn) and methylmercury in an Indian tarantula Thrigmopoeus truculentus (Pocock 1899) of the Western Ghats

Abstract

ABSTRACTSpiders are good bioindicators of ecological contamination by potentially toxic trace elements such as As, Cd, Hg, In, Ni, Pb, Se Zn and methylmercury (MeHg). Here, we investigated their bioaccumulation in an Indian tarantula, Theraphosidae spider Thrigmopoeus truculentus inhabiting mud embankments along a national highway in the Western Ghats mountains, and the soil contamination. Concentrations in soil were higher than the soil environmental quality criteria of different countries for Cd, Zn and Ni. Concentrations in whole-body of tarantulas (n = 7) were Zn > Se > [Cd, As, Pb, Ni] > In > total mercury (THg) > MeHg. Concentrations of Zn, Cd, Se, THg and MeHg were significantly higher (p < 0.05) compared to soil, suggesting biomagnification. Our work and the review of past data suggest that spiders can biomagnify Zn, Cd, Se, THg and MeHg; but not Pb, As, In and Ni. For As, Zn, Se, Cd, In and THg, correlations between concentrations in tarantula appendages and whole-body were significant (p < 0.05), suggesting that a non-lethal approach be explored where only appendages of larger tarantulas are analysed. Overall, the Theraphosidae species showed the potential to be used as an indicator of bioaccumulation, and their usefulness should be further explored.KEYWORDS: IndiaWestern GhatsTarantulapotentially toxic trace elements and methylmercurybioaccumulation AcknowledgementsMRB gratefully acknowledges the Goa State Biodiversity Board for permitting a limited collection of spider specimen for this experimental work. Prakash Salelkar, Retd. Range Forest Officer, Goa State Forest Department rendered valuable assistance in field collection. We thank Aayush Dubay for help in making Figure 2, and lab support provided by Mayuri Bhatia and Mohini Seth.Disclosure statementNo potential conflict of interest was reported by the author(s).Data availability statementThe data that support the findings of this study are available on reasonable request from the corresponding author.Additional informationFundingThis work was supported by the Department of Science and Technology, Ministry of Science and Technology, India [grant number IFA-13 EAS-10].Notes on contributorsManoj Ramakant BorkarManoj Ramakant Borkar is an associate professor and Head of the Department of Zoology at Carmel College for Women, Goa, India. He has made a seminal contribution to documenting the faunal diversity of Goa, a Western Ghats state and has contributed to developing National and State Biodiversity Strategy and Action Plans in India, besides writing wildlife management plans for two protected areas of the state of Goa. He has also served on the Wildlife Board and Experts Committee for Environment Impact Assessment in Goa. His current research interests are the micro-morphology of arachnids, the chemical ecology of uropygi, and the eco-toxicological evaluation of terrestrial food chains using spider models.Asif QureshiAsif Qureshi is an associate professor at IIT Hyderabad, department of civil engineering and the department of climate change. Dr. Qureshi's research interest is in the general area of environmental chemistry, namely in understanding the fate and transport of trace contaminants in the environment, their bioaccumulation and the associated environmental and human health risks, at present and in the future. His group employs a combination of experimental and modelling tools and works on topics of relevance at local, regional and global scales.