Sub-lethal toxicities of zinc pyrithione, copper pyrithione alone and in combination to the indicator mussel species Unio crassus Philipsson, 1788 (Bivalvia, Unionidae)

ABSTRACT

Zinc pyrithione (ZnPT) and copper pyrithione (CuPT) are widely used antifouling booster biocides in the shipping industry as a replacement for the banned tributyltin (TBT). Sub-lethal effects of zinc pyrithione (ZnPT; 10 μg L⁻¹), copper pyrithione (CuPT; 10 μg L⁻¹) and combined copper–zinc pyrithione (CZPT; 5 + 5 and 10 + 10 μg. L⁻¹) to freshwater indicator mussel Unio crassus (5.49 ± 0.85 cm in size) were determined by investigation of the total hemocyte counts, biochemical analysis mussel tissues and histopathological observations after 48-h and 7-d exposures. Mean total hemocyte counts differed significantly among all groups, for both exposure durations. In the 7 d, lipid peroxidation levels (malondialdehyde, MDA nmol g⁻¹ wet tissue) and reduced glutathione levels (GSH μmol g⁻¹ wet tissue) were lower than 48 h. However, there were no significant differences among groups. Total protein levels (mg mL⁻¹) were approximately in the same range and differed only among 7-d exposure groups. The gill tissues showed hemocytic infiltration and lipofuscin like structures, while digestive gland showed loss of digestive tubules in the treatments of pyrithione compounds. Histopathological damages were most severe in the combined exposure groups. In conclusion, ZnPT, CuPT and combined CZPT_5/10 are highly toxic on a freshwater indicator mussel species U. crassus.

KEYWORDS:

• Zinc pyrithione
• copper pyrithione
• Unio
• sub-lethal test
• histopathology
• biochemical assays

Acknowledgments

N. Třešňáková would like to thank the EU Erasmus+ programme for a mobility internship (no: 12/2018-2019/FROV) and Gazi University, Turkey, for making available the facilities and laboratory to carry out the research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes on contributors

Nikola Třešňáková is MSc student at Faculty of Fisheries and Protection of Waters, the University of South Bohemia in České Budějovice, Czech Republic; and Erasmus trainee at Department of Biology Education at Gazi University, Turkey.

A. Çağlan Günal is the Head of the Department of Environmental Sciences, Graduate School Natural and Applied Sciences and Professor at Gazi Education Faculty, Department of Biology Education at Gazi University.

Gökben Başaran Kankılıç is a research assistant in the Department of Biology, adjunct appointment in Environmental Analysis Laboratory of Kırıkkale University Scientific and Technologic Researches Application and Research Centre.

Elif Paçal completed her MSc degree in Biology Department, Gazi University.

Ü. Nihan Tavşanoğlu is an Associate Professor at Eldivan Vocational School of Health Services, Department of Environmental Health at Çankırı Karatekin University.

Recep Uyar is a graduate student at the Department of Pharmacology and Toxicology, Veterinary Faculty, the University of Ankara in Turkey.

Figen Erkoç, the Professor, works at Gazi Education Faculty, Department of Biology Education at Gazi University.

ORCID

Nikola Třešňáková http://orcid.org/0000-0002-1756-0595

A. Çağlan Günal http://orcid.org/0000-0002-9072-543X

Gökben Başaran Kankılıç http://orcid.org/0000-0001-7551-4899

Elif Paçal http://orcid.org/0000-0001-6271-4269

Ü. Nihan Tavşanoğlu http://orcid.org/0000-0001-8462-415X

Recep Uyar http://orcid.org/0000-0002-7788-6685

Figen Erkoç http://orcid.org/0000-0003-0658-2243