The effects of artificial light on the behavior of Eastern Mosquitofish (Gambusia holbrooki) in Iran

Around 83 percent of the world's population live in light-polluted areas, of which 40 percent live in places that are continuously lit by “ALAN (Artificial Light at Night)”. The light pollution caused by “ALAN” is growing day by day. Thus, the risk of environmental damage is growing in aquatic areas by increasing the “ALAN”. In this way, this research investigates the artificial light at night’s a “ALAN” effect on Gambusia Holbrooke “mosquitofish” in Iran. To obtain the ALAN data, we relied on the information from the operational linear satellite scanning data related to the Metrological Defense Satellite Program (DMSP/OLS). the data provided by the DMSP satellite belonged to 1992 and 2013 as images. The images were clipped by the geographical information systems (GIS), and the images were classified into five classes based on the light pollution intensity. Afterwards, the changes in light pollution by area were calculated and reported. The aim of this research was to examine the effect of ALAN on the Gambusia holbrooki. Two types of treatments were provided for G. holbrooki: control and ALAN treatments. In both treatments, fish were kept for 60 days, and after that period, their shoaling and hiding behaviors were examined and recorded by a web camera. The results indicated that by increasing the ALAN, especially near the coastlines, the risk of harmful effects on G. holbrooki could be increased. The findings suggested that the ALAN might influence G. holbrooki behavior. The shoaling behavior of the ALAN treatments samples revealed that the time spent shoaling individually at night and during the day was decreased. As a result, in the hiding behavior experiment, G. holbrooki moved less at night after ALAN exposure but did not hide, indicating that the fish are unlikely to swim away or hide when exposed to light at night. As a result, they may be more vulnerable to predation.