Presence of pharmaceuticals in benthic fauna living in a small stream affected by effluent from a municipal sewage treatment plant

Highlights

• Pharmaceuticals bioaccumulate in benthic fauna living downstream the effluent.

• Azithromycin, clarithromycin, verapamil and citalopram were found in Hydropsyche.

• Diclofenac and valsartan were determined in Erpobdella.

• Only sertraline and clotrimazole were found in both studied species.

• Uptake of pharmaceuticals via food web can be important exposure pathway for fish.

Abstract

Aquatic organisms can be affected not only via polluted water but also via their food. In the present study, we examined bioaccumulation of seventy pharmaceuticals in two benthic organisms, Hydropsyche sp. and Erpobdella octoculata in a small stream affected by the effluent from a sewage treatment plant (STP) in Prachatice (South Bohemia region, Czech Republic).

Furthermore, water samples from similar locations were analyzed for all seventy pharmaceuticals. In water samples from a control locality situated upstream of the STP, ten of the seventy pharmaceuticals were found with average total concentrations of 200 ng L⁻¹. In water samples collected at STP-affected sites (downstream the STP′s effluent), twenty-nine, twenty-seven and twenty-nine pharmaceuticals were determined at average total concentrations of 2000, 2100 and 1700 ng L⁻¹, respectively.

Six of the seventy pharmaceuticals (azithromycin, citalopram, clarithromycin, clotrimazole, sertraline, and verapamil) were found in Hydropsyche. Four pharmaceuticals (clotrimazole, diclofenac, sertraline, and valsartan) were detected in Erpobdella. Using evaluation criterion bioconcentration factor (BCF) is higher than 2000 we can assign azithromycin and sertraline as bioaccumulative pharmaceuticals. Even pharmaceuticals present at low levels in water were found in benthic organisms at relatively high concentrations (up to 85 ng g⁻¹ w.w. for azithromycin). Consequently, the uptake of pharmaceuticals via the food web could be an important exposure pathway for the wild fish population.

Introduction

Effluent of municipal sewage treatment plants (STPs) contains numerous organic and inorganic pollutants due to insufficient removal efficiency during the treatment processes (Golovko et al., 2014a, Halling-Sorensen et al., 1998, Heberer, 2002, Petrovic et al., 2003). This incomplete removal broadly reflects the pharmaceuticals mixture to which fish and other aquatic organisms are typically exposed (Verlicchi et al., 2012).

Most of the research examining the possible bioconcentration of environmental contaminants in fish has focused on either controlled laboratory conditions associated with known individual pharmaceuticals or mixture exposure (e.g. Brozinski et al., 2013, Cuklev et al., 2012, Lahti et al., 2011, Nallani et al., 2011, Steinbach et al., 2013) or on fish placed into cages and exposed directly to the effluent (e.g. Lajeunesse et al., 2011, Togunde et al., 2012). It means that bioconcentration is the prevailing or only exposure mechanism. However, intake of pollutants via contaminated natural food is completely ignored in these experimental setups. Depending on the exposure period, fish are either not fed or artificial feed is used. In the case of real conditions, fish in cages can be stressed and outcomes of these experiments do not truly mimic the natural conditions.

Aquatic organisms are exposed not only via the discharge of sewage waters but also via their food web. Benthic fauna is a very important part of the food web in aquatic environments (e.g. Hellmann et al., 2013, Hildrew, 1992). Benthic organisms are often used as bioindicators for assessing environmental pollution due to their limited movability and relatively easy sampling (Clews et al., 2014, Cortes et al., 2013, Pan et al., 2012, Smith et al., 1999). Larvae of caddisflies (Hydropsyche sp.) and leeches (Erpobdella sp.) are often used as indicators of water quality or pollution in streams (Azrina et al., 2006, Koperski, 2005, Koperski, 2010, Sola and Prat, 2006, Stuijfzand et al., 1999, Tessier et al., 2000). These species have been used for monitoring of riverine pollution in the Czech Republic during the last decade (Kolarikova et al., 2012, Macova et al., 2009). These organisms significantly contribute to a fish diet as well (Elliott, 1967, Greenberg and Dahl, 1998, Laine, 2001, Reiriz et al., 1998).

The aim of this study was to investigate pharmaceutical levels in benthic organisms and consequently to reveal their importance in the exposure pathways of the fish.