Induction of carboxylesterase activity in Chilina gibbosa after a short term exposure to river water polluted by a natural petroleum spill

HERBERT, L.T.; LEGGIERI, L.R.; DE ANNA, J.S.; LUQUET C.M.; KRISTOFF, G.

CABA

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

SETAC Latin America

Las Minas stream is located southeast of the city of San Carlos de Bariloche in the south of Argentina (41°17?21?? S, 71°10?58?? O, 1001 msnm). Between 1910 and 1940 natural reserves of crude oil near to the stream were exploited commercially until the activity stopped and the source was abandoned leaving behind an oil spill that affects Las Minas and also downstream water bodies. Chilina gibbosa is a freshwater gastropod native to most streams and lakes of southern Argentina and Chile and could be one of several non-target species affected by exposure to polycyclic aromatic hydrocarbons (PAH) present in Las Minas. The aim of this study was to evaluate the effects of sample water from Las Minas on the activity of carboxylesterases (CEs) in C. gibbosa. Bioassays were carried out exposing snails to clean river water (Control, C), river water from a contaminated site in Las Minas (River Water, RW) and to a 1% dilution of the water soluble fraction of the petroleum found in the contaminated site in Las Minas (Water Soluble Fraction, WSF) for 48 hours. CEs activity was measured using p-nitrophenyl acetate (p-NFA) and p-nitrophenyl butirate (p-NFB) as substrates. At the end of the exposure period, a noticeable difference in pigmentation was observed. Snails exposed to petroleum (RW and WSF) presented a darker foot area than control animals. Animals exposed to river water from Las Minas (RW) showed an activation effect of 65% with respect to control animals in CEs activity measured with p-NFB (p>0.05). CEs activity measured with p-NFB of animals exposed to the 1% dilution (WSF) did not differ significantly from CEs activities of control nor RW snails. No differences were found in CEs activity between control and exposed animals when p-NFA was used as substrate. As a first approach to the subject, this study shows that C. gibbosa is affected by petroleum that might be present in its natural habitat as is the case in Las Minas stream and that CEs activity could be a useful biomarker of PAH.