Meeting Abstract
Artificial light at night (ALAN) is light that alters the natural light and dark cycle in an ecosystem and includes streetlights, headlights and flood lights. An estimated two-thirds of the world population is living in areas above the light pollution threshold. ALAN is known to have detrimental effects on wildlife by altering reproduction, foraging, predation, physiology, and orientation in multiple taxa. We used (Gambusia affinis), a widespread live-bearing fish, to study the effects of ALAN by exposing female fish to a constant light cycle and comparing cortisol, reproductive success, behavior and growth to those kept under a natural light cycle. We predicted that fish exposed to ALAN would have increased cortisol levels and activity compared to fish kept under a normal light cycle. We measured cortisol release rates five times over 60 days using a water-borne collection method. Cortisol is the primary glucocorticoid in fish and is indicative of an organism’s physiological response to disturbance, therefore is an important parameter to measure when looking at anthropogenic influences such as ALAN. Under chronic stress cortisol may become permanently elevated or depressed and could suppress growth and reproduction. To examine this, we measured the stress response to agitation on day 60. We also explored the number and condition of broods from fish exposed to ALAN versus those in the control treatment. Results demonstrate that female (G. affinis) exposed to ALAN have lower mass compared to those in the control treatment.
