Abstract
Larval metamorphosis and recruitment represent critical life-history transitions for most teleost fishes. While the detrimental effects of anthropogenic stressors on the behavior and survival of recruiting fishes are well-documented, the physiological mechanisms that underpin these patterns remain unclear. Here, we use pharmacological treatments to highlight the role that thyroid hormones (TH) play in sensory development and determining anti-predator responses in metamorphosing convict surgeonfish, Acanthurus triostegus. We then show that high doses of a physical stressor (increased temperature of +3 °C) and a chemical stressor (the pesticide chlorpyrifos at 30 µg L−1) induced similar defects by decreasing fish TH levels and affecting their sensory development. Stressor-exposed fish experienced higher predation; however, their ability to avoid predation improved when they received supplemental TH. Our results highlight that two different anthropogenic stressors can affect critical developmental and ecological transitions via the same physiological pathway. This finding provides a unifying mechanism to explain past results and underlines the profound threat anthropogenic stressors pose to fish communities.
Highlights
Larval metamorphosis and recruitment represent critical life-history transitions for most teleost fishes
To study sensory development during metamorphosis, wild settlement-stage A. triostegus were collected at night, while they were moving from the pelagic environment to the reef, using a crest net[11]
We investigated the role of thyroid hormones (TH) in the development of these sensory structures by injecting fish daily from d0 to d5 with different pharmacological drugs: (i) T3 + iopanoic acid (T3 treatment) to achieve TH signal activation, and (ii) NH3 to achieve TH signal disruption[11]
Summary
Larval metamorphosis and recruitment represent critical life-history transitions for most teleost fishes. Myriad recent studies have reported that various anthropogenic stressors, such as artificial light pollution[17], increasing temperature[18,19,20], ocean acidification[21,22], sound pollution[23,24], and waterborne chemical pollutants[11,14,25] can lead to the deterioration of ecologically important behaviors, including the ability to detect predators and avoid predation. We use the coral-reef-dwelling convict surgeonfish, Acanthurus triostegus, to investigate the importance of the TH endocrine pathway on sensory development during metamorphosis, whether exposure to two distinct anthropogenic stressors (increased temperature and the waterborne organophosphate pesticide chlorpyrifos) can cause TH signaling disruption, and whether the resulting impacts on sensory development increase vulnerability to predation
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