Ecotoxicological studies with newly hatched larvae of Concholepas concholepas (Mollusca, Gastropoda): bioassay with secondary-treated kraft pulp mill effluents Patricio H. Manríquez a,n , Alejandra Llanos-Rivera b , Sylvana Galaz a , Andrés Camaño c a Instituto de Ciencias Marinas y Limnológicas, Laboratorio Costero de Recursos Acuáticos de Calfuco, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile b Universidad de Concepción, Facultad de Ciencias Naturales y Oceanográficas Unidad de Biotecnología Marina, Concepción, Chile c Golder Associates, Magdalena 181, Floor No 3, Las Condes, Santiago, Chile article info Article history: Received 11 June 2013 Received in revised form 10 September 2013 Accepted 12 September 2013 Available online 5 October 2013 Keywords: Marine pollution monitoring Pulp effluent Bioassay Gastropod Newly-hatched larvae Chile abstract The Chilean abalone or “loco” (Concholepas concholepas, Bruguière 1789) represent the most economically important marine recourse exploited from inner inshore Management and Exploitation Areas for Benthic Resources along the Chilean coast. In this study, newly-hatched larvae of C. concholepas were investigated as a potential model species for marine ecotoxicological studies. The study developed a behavioral standard protocol for assessing the impact that kraft pulp mill effluents after secondary treatment have on C. concholepas larvae. Under controlled laboratory conditions, newly-hatched larvae were exposed to a series of different concentrations of kraft pulp mill effluents with secondary treatment (Pinus spp. and Eucalyptus spp.), potassium dichromate as standard reference toxicant and effluent-free control conditions. Regardless of the type of effluent the results indicated that diluted kraft pulp effluent with secondary treatment had reduced effect on larval survival. Low larval survivals were only recorded when they were exposed to high concentrations of the reference toxicant. This suggests that C. concholepas larval bioassay is a simple method for monitoring the effects of kraft pulp mill effluents with secondary treatment discharged into the sea. The results indicated that dilution of ca. 1% of the effluent with an elemental chlorine free (ECF) secondary treatment is appropriate for achieving low larval mortalities, such as those obtained under control conditions with filtered seawater, and to minimize their impact on early ontogenetic stages of marine invertebrates such as newly-hatched larvae of C. concholepas. The methodological aspects of toxicological testing and behavioral responses described here with newly-hatched larvae of C. concholepas can be used to evaluate in the future the potential effects of other stressful conditions as other pollutants or changes in seawater pH associated with ocean acidification. & 2013 Elsevier Inc. All rights reserved. 1. Introduction There is evidence that coastal industrial activities may have lethal and sublethal effects on fresh water and marine biota and particularly on larval behavior, affecting their ability to disperse and settle (Raimondi and Reed, 1996). In the paper and cellulose industry the pulping is commonly done in a two step process: (a) a chemical process that removes cellulose from wood dissolving lignin, (b) a bleaching process that removes chromophores (US EPA, 2002). The adverse effects of pulp mill effluents on aquatic systems have been described in the literature and are mainly associated with toxic substances (Colodey and Wells, 1992). To reduce pollutant discharges and oxygen demand pulp mill effluents commonly use secondary or biological treatments on the effluents (Zender et al., 1994). However, some toxic chemical compounds have been shown to be recalcitrant, compromising the effectiveness of such biological treatments (Catalkaya and Kargi, 2008). In central and southern Chile the operation of kraft pulp mills is an important economic activity, reporting during 2008–2011 an average net income of US$ 740 million/year (Banco Central de Chile, 2008–11). The inland Celulosa Arauco y Constitución S.A (hereafter Arauco) kraft pulp mill plant at Valdivia (39133'37"S; 72153'20"W) has been in operation since 2004, discharging tertiary treated effluents of Pinus spp. and Eucalyptus spp. into the Cruces River, province of Valdivia. In the near future, as part of the legal requirement, the secondary treatment kraft pulp mill effluents from the Arauco plant at Valdivia would be discharged directly into the sea and not into the Cruces River. Under this new scenario the secondary treatment kraft pulp mill effluents produced by the Arauco plant at Valdivia will be sent along a Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ecoenv Ecotoxicology and Environmental Safety 0147-6513/$ - see front matter & 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ecoenv.2013.09.015 n Corresponding author. Present address: Laboratorio de Ecología y Conducta de la Ontogenia Temprana (LECOT), Centro de Estudios Avanzados en Zonas Áridas (CEAZA). Avenida Ossandón 877, Coquimbo, Chile. E-mail address: patriciohmanriquez@gmail.com (P.H. Manríquez). Ecotoxicology and Environmental Safety 98 (2013) 110–118