Please cite this article in press as: Di Poi, C., et al., Cryptic and biochemical responses of young cuttlefish Sepia officinalis exposed to environmentally relevant concentrations of fluoxetine. Aquat. Toxicol. (2014), http://dx.doi.org/10.1016/j.aquatox.2013.12.026 ARTICLE IN PRESS G Model AQTOX-3721; No. of Pages 10 Aquatic Toxicology xxx (2014) xxx–xxx Contents lists available at ScienceDirect Aquatic Toxicology jou rn al hom ep age: www.elsevier.com/locate/aquatox Cryptic and biochemical responses of young cuttlefish Sepia officinalis exposed to environmentally relevant concentrations of fluoxetine Carole Di Poi a,b , Flavie Bidel a,b , Ludovic Dickel a,b , Cécile Bellanger a,b,∗ a Universit´ e de Caen Basse-Normandie, France b Groupe M´ emoire et Plasticit´ e comportementale, EA 4259, F-14032 Caen cedex, France a r t i c l e i n f o Article history: Received 31 August 2013 Received in revised form 22 December 2013 Accepted 24 December 2013 Keywords: Cephalopods Selective Serotonin Reuptake Inhibitors (SSRI) Fluoxetine Camouflage Locomotor activity Sand digging behavior Monoamines a b s t r a c t Antidepressants released in the environment have the potential to generate neural disrupting effects in non-target organisms, yet their putative effects on behaviors have never been studied in cephalopod molluscs. This study assessed the impact of the antidepressant fluoxetine (FLX) on the efficiency of cryptic behaviors (body patterns on uniform, checkerboard and sandy substrates), locomotor activity, and brain chemistry in young cuttlefish exposed to environmental concentrations (1 and 100 ng L -1 of FLX) dur- ing the perinatal period. Behavioral responses of cuttlefish were monitored at hatching and two weeks later, and brain monoamine contents were quantified at one month of age. FLX significantly altered the camouflage efficiencies on uniform and sandy backgrounds only at the lowest concentration, but not at 100 ng L -1 . Hatchlings exposed to 1 ng L -1 of FLX exhibited a duration exposure-dependent decrease in the uniform camouflage. They also showed a significant increase of the frequency of sand digging behaviors which might make them highly visible to predators in nature. When tested again two weeks later, cuttlefish seemed to have recovered and no more behavioral alterations were observed showing a transitory effect of the antidepressant. FLX did not affect the levels of serotonin, norepinephrine and their metabolites; however, it seemed to influence dopaminergic activity between the two FLX-exposed groups. The results show for the time that environmentally realistic concentrations of a single SSRI sig- nificantly impair the cryptic performances of newly hatched cuttlefish, and may ultimately reduce their chance for survival. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The coleoid cephalopods (octopuses, cuttlefishes and squids) display unique defensive behaviors controlled by one of the most sophisticated nervous system within invertebrates (Nixon and Young, 2003; Dickel et al., 2013). They express two major antipredator strategies (reviewed in Hanlon and Messenger, 1996). The first one, called primary defense, serves to reduce the chance of being detected by a potential predator using cryptic behaviors. Cephalopods can rapidly change color and exhibit different body patterns. According to Hanlon and Messenger (1988), the cuttle- fish Sepia officinalis can adopt three main types of body patterns for camouflage when settled on the bottom: “uniform/stipple”, “mot- tle” and “disruptive” that can be regarded as mosaics varying in color, shape, size, intensity and texture. Uniform patterns are usu- ally displayed on uniform backgrounds, whereas cuttlefish exhibit ∗ Corresponding author at: Universit ´ e de Caen Basse-Normandie, France. Tel.: +33 231 566 879. E-mail addresses: carole.dipoi@gmail.com (C. Di Poi), favie.bidel@unicaen.fr (F. Bidel), ludovic.dickel@unicaen.fr (L. Dickel), cecile.bellanger@unicaen.fr (C. Bellanger). more complex patterns such as mottle pattern on sandy bottoms or disruptive pattern on contrasted substrates containing gravel, peb- bles or shells. This extraordinary ability is due to the presence of chromatophores on their skin; i.e. neuromuscular organs controlled by optic lobes in the brain involved in the integration of visual infor- mation that serve on body patterning (Messenger, 2001). Among other cryptic behaviors, the cuttlefish can bury in sand to avoid potential predators (Mather, 1986; Boletzky, 1987). In the genus Sepia, digging is a relatively short and fixed behavioral sequence lasting less than 5 s on fine sand (Mather, 1986). Secondary defenses are used when the cuttlefish has already been detected by a preda- tor. Threat displays include flight response frequently accompanied with ink ejection, as well as deimatic behavior characterized by the appearance of black eyespots on the dorsal mantle of the ani- mal (reviewed in Hanlon and Messenger, 1996). Cuttlefish are able to exhibit all these complex behaviors from hatching; although their expression needs adjusting and improves with development and learning from their environment (Poirier et al., 2004, 2005). A recent study shows that xenobiotic pollutants discharged in the marine environment can impact cognitive abilities of young cut- tlefish and may ultimately modify these basic behaviors (Di Poi et al., 2013). We showed that chronic exposures to environmentally relevant concentrations of the antidepressant fluoxetine impair 0166-445X/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aquatox.2013.12.026