Effect of Antidepressant on the Agonistic Behaviour of Crayfish (Orconectes rusticus, the rusty crayfish)

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Project Abstract: 
Pharmaceuticals extensively used in human and veterinary prescription were invisible pollutants in the aquatic environment until the 1960s. Now, its presence in aquatic environments, especially in surface water samples has gained environmental concern (Burkina et al., 2015) and considered as an emerging contaminants (Ebele et al., 2017). Pharmaceuticals from human or animal excretion, industrial waste, runoff from hospitals, or improper disposal (Chang et al., 2007; Escher et al., 2011; Frédéric and Yves, 2014; Loos et al., 2013) find their way to surface waters via sewage treatment plants (STPs) effluents where are removed from sewage waters only partially or not at all (Blair et al., 2013; Golovko et al., 2014; Heberer, 2002). Therefore, nonsteroidal anti-inflammatory drugs (NSAIDs), fibrates, ß-blockers, selective serotonin reuptake inhibitors (SSRIs), azoles and antibiotics (Loos et al., 2013) are most common mixture of pharmaceuticals residues then in the waters and sediments at concentration ranges from ng to µg/l. Though standard acute toxicity test of a number of pharmaceuticals there is reported no acute toxicity to aquatic organisms, as their low environmental concentration (10-1000ng.l-1) (Fent et al., 2006). However, these residues could have non-lethal effects non-target organisms and ecosystems (Boxall et al., 2012) as they are designed to be effective at low concentration levels on target organisms (Huerta et al., 2012; Hughes et al., 2013; Kaushik et al., 2016; Santos et al., 2010). Most of the environmentalist and toxicologist are focused on antibiotics or hypertension drugs (Carlson et al., 2017; Godoy et al., 2015; Grenni et al., 2018; Parrott and Balakrishnan, 2017; Zhou et al., 2018) as occurring environmentally in the highest frequency and highest concentration (Marti et al., 2018; Stankiewicz et al., 2015) than e.g. antidepressant being present at lower concentration at surface water compared to the internal human therapeutic dose (Cmax 0.19 mg.ml-1) (Schulz et al., 2012). Nevertheless, antidepressants, such as selective serotonin re-uptake inhibitors (SSRI), are of particular interest as they have behavioural effects on organisms exposed (Brodin et al., 2014; Hamilton et al., 2016; Tain et al., 2006; Woodman et al., 2016) even at environmental concentration (Guler and Ford, 2010; Kaushik et al., 2016; Valenti et al., 2009). These effects could be exaggerated due to its bioaccumulation potentials in tissue and brain of fish, benthos or crayfish (Fong and Ford, 2014; Grabicova et al., 2014, 2015, 2017). These antidepressants are designed to block serotonin reuptake transporters and creating an alter state by flooding the brain with the neurotransmitter, serotonin (Fedorova et al., 2014; Hyttel, 1994). It has been identified that serotonin worked as a modulator of anxiety like behaviour in crayfish (Fossat et al., 2015; Fossat et al., 2014) which are displayed during formation of social hierarchy in a population. Therefore, formation of social hierarchy greatly depend on serotonin level (Huber and Delago, 1998; Sneddon et al., 2000) and these elevated level of serotonin in individual’s brain can increase the likelihoods of subsequent winning (Bergman et al., 2003). It can be assumed that unexpected fluctuation of serotonin level may alter the social hierarchy, population structure and ecosystem functions. Former studies on the alteration of crayfish behaviour by antidepressants exhibited a decreased willingness to retreat (Huber and Delago, 1998; Huber et al., 2001; Momohara et al., 2013; Panksepp and Huber, 2002), win against larger naïve opponents (Momohara et al., 2013) and more aggressive behaviour than unexposed opponent (Woodman et al., 2016). However, in these studies crayfish were commonly treated by antidepressant either direct injection, infusion or exposure in aqueous solution of different graded concentrations, for specific period of time at static water (Harrigan and Moore, 2017). Only little is known about effects of environmentally relevant concentration of these compounds at natural stream system. It must be mentioned that introduction of anthropogenic chemicals to natural systems are typically not steady-state (e.g., pesticide runoff from a recently treated agricultural field, industrial chemical spills, and roadway runoff following a rain event). Spatial and temporal fluctuations are dependent on season, physicochemical properties, removal rates in the STPs, stream/river dilution factors, turbulence as well as habitat structures of stream (Harrigan and Moore, 2017). Therefore, it is necessary to consider the exposure variability of dynamic natural system during evaluation of toxicity of particular pollutants on their representative inhabitants. However, some antidepressants can bio-accumulate (Grabicova et al., 2017) in brain of exposed animals and affect them for longer time than during exposure period itself. It could be assumed that effect of antidepressant will be variable in dynamic exposure stream, but having high capability to persist in aquatic ecosystems. The aim of this study is to know how antidepressants can influence the aquatic organisms’ behaviour in natural systems.
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