Exposure to agricultural pesticide impairs visual lateralization in a larval coral reef fish

Abstract

Lateralization, i.e. the preferential use of one side of the body, may convey fitness benefits for organisms within rapidly-changing environments, by optimizing separate and parallel processing of different information between the two brain hemispheres. In coral reef-fishes, the movement of larvae from planktonic to reef environments (recruitment) represents a major life-history transition. This transition requires larvae to rapidly identify and respond to sensory cues to select a suitable habitat that facilitates survival and growth. This ‘recruitment’ is critical for population persistence and resilience. In aquarium experiments, larval Acanthurus triostegus preferentially used their right-eye to investigate a variety of visual stimuli. Despite this, when held in in situ cages with predators, those larvae that previously favored their left-eye exhibited higher survival. These results support the “brain’s right-hemisphere” theory, which predicts that the right-eye (i.e. left-hemisphere) is used to categorize stimuli while the left-eye (i.e. right-hemisphere) is used to inspect novel items and initiate rapid behavioral-responses. While these experiments confirm that being highly lateralized is ecologically advantageous, exposure to chlorpyrifos, a pesticide often inadvertently added to coral-reef waters, impaired visual-lateralization. This suggests that chemical pollutants could impair the brain function of larval fishes during a critical life-history transition, potentially impacting recruitment success.

Anthropogenic stressors impact fish sensory development and survival via thyroid disruption

“…5b). We only investigated the right eye of A. triostegus fish, as evidence suggests this species is visually lateralized at recruitment, and predominantly uses its right eye to examine visual predator stimuli 14 . Also, we only examined the dorsal side of the retina, as the ventral side (vs) was shown to not undergo change at metamorphosis in another coral-reef fish species, the goatfish Upeneus tragula 13 ( Supplementary Fig.…”

Brain and Behavioral Asymmetry: A Lesson From Fish

“…Other stressors that disrupt lateralization are ocean warming (Domenici et al, 2014), anthropogenic noise in aquatic environments (e.g., commercial shipping and recreational boating) (Simpson et al, 2015), chemical pollutants added to water (i.e., pesticide) (Besson et al, 2017) and hypoxia that is exacerbated by human activities (e.g., agriculture and discharge of raw sewage) that increases coastal eutrophication (Lucon-Xiccato et al, 2014). It is clear from these studies that some environmental factors affecting lateralization are due anthropic activities and that management and policy decisions are needed to reduce their negative effects on fish behavior that can, in turn have severe implications for community structure and ecosystem function.…”

Detailed movement and laterality of fin-biting behaviour with special mouth morphology inGenyochromis mentoin Lake Malawi

“…Despite the fact that individual laterality in behavioural responses is observed among many fish (e.g. Bisazza et al, 1997;Heuts, 1999;Izvekov et al, 2009;Reddon and Hurd, 2009;Bisazza and Brown, 2011;Domenici et al, 2014;Ferrari et al, 2015;Besson et al, 2017), appearance pattern and the interspecific difference of behavioural laterality remain contentious matters. Additional investigations into the levels of laterality in species with different feeding habits will improve our understanding of the ecological significance of laterality.…”