The biological effects of antidepressants on the molluscs and crustaceans: A review

Abstract

Antidepressants are among the most commonly detected human pharmaceuticals in the aquatic environment. Since their mode of action is by modulating the neurotransmitters serotonin, dopamine, and norepinephrine, aquatic invertebrates who possess transporters and receptors sensitive to activation by these pharmaceuticals are potentially affected by them. We review the various types of antidepressants, their occurrence and concentrations in aquatic environments, and the actions of neurohormones modulated by antidepressants in molluscs and crustaceans. Recent studies on the effects of antidepressants on these two important groups show that molluscan reproductive and locomotory systems are affected by antidepressants at environmentally relevant concentrations. In particular, antidepressants affect spawning and larval release in bivalves and disrupt locomotion and reduce fecundity in snails. In crustaceans, antidepressants affect freshwater amphipod activity patterns, marine amphipod photo- and geotactic behavior, crayfish aggression, and daphnid reproduction and development. We note with interest the occurrence of non-monotonic dose responses curves in many studies on effects of antidepressants on aquatic animals, often with effects at low concentrations, but not at higher concentrations, and we suggest future experiments consider testing a broader range of concentrations. Furthermore, we consider invertebrate immune responses, genomic and transcriptomic sequencing of invertebrate genes, and the ever-present and overwhelming question of how contaminant mixtures could affect the action of neurohormones as topics for future study. In addressing the question, if antidepressants affect aquatic invertebrates at concentrations currently found in the environment, there is strong evidence to suggest the answer is yes. Furthermore, the examples highlighted in this review provide compelling evidence that the effects could be quite multifaceted across a variety of biological systems.

Prozac in the water: Chronic fluoxetine exposure and predation risk interact to shape behaviors in an estuarine crab

“…Perhaps fluoxetine, through modulation of serotonin levels, stimulates crab activity levels and drives aggressive behaviors. Fluoxetine's effect on serotonin levels appears to increase boldness and potentially other risk behaviors as studies on other species have suggested (Dzieweczynski & Hebert, 2012; Fong & Ford, 2014; Mesquita et al., 2011; Pedetta et al., 2010; Tierney & Mangiamele, 2001). …”

“…Serotonin and serotonin analogs have been shown to alter agonistic behaviors (McPhee & Wilkens, 1989; Tierney & Mangiamele, 2001) and activity levels (Fong & Ford, 2014; Perez‐Campos, Rodriguez‐Canul, Perez‐Vega, Gonzalez‐Salas, & Guillen‐Hernandez, 2012) in crustaceans. Fluoxetine concentrations ≥120 μg/L caused a stimulation of locomotor behavior in the crab Carcinus maenas (Mesquita et al., 2011).…”

Medicating the environment: assessing risks of pharmaceuticals to wildlife and ecosystems

“…However, there is still some argument as to whether it is more applicable as a biomarker of oestrogen exposure rather than effect [69]. There is also a growing concern over psychoactive drugs because they are designed to alter (human) behaviour and have side effects that could also influence fitness-related traits in free-living animals [11,15,55,70] (table 1 and §6). Recalling the 'read-across' hypothesis ( §3), there are a number of reasons why compounds designed to have therapeutic effects in humans and livestock could impact nontarget animals and ecosystems: there is strong evolutionary conservation of drug targets across phyla; pharmaceuticals are generally highly potent, and long term, low-level exposure due to their continual release to the environment is likely to lead to chronic effects; for some pharmaceuticals, mode of action is associated with a potentially harmful effect (e.g.…”

Potential ecological footprints of active pharmaceutical ingredients: an examination of risk factors in low-, middle- and high-income countries

“…Despite these examples, there has been a notable lack of studies that demonstrate effects of APIs based on ecologically relevant assessments, with respect to appropriate exposure concentrations and duration, ecotoxicological endpoints and implications of mixture effects [7,8]. However, where ecologically appropriate exposures were used, APIs have been demonstrated to cause effects in organisms, such as behaviour and reproduction, which may have broader ecological consequences [7,[9][10][11][12][13][14].…”