Effects of hypoxia on lateralization in three coastal species of fish

Coastal fish are daily subjected to several environmental changes mainly due to tidal rhythms. Hypoxic conditions are widespread in many coastal habitats and their occurrences have been increasing over the past years thanks to human activities. Our study used a simple turning preferences test (detour test) to assess the effects of hypoxia in fish behavioral lateralization using three commonly diffused coastal species as a model (Cymatogaster aggregata, Gasterosteus aculeatus and Leptocottus armatus). We found that hypoxia exposure disrupts behavioral lateralization at population level in Leptocottus armatus. In the population used in our experiment individuals showed a distinct preference for right turns in the detour test. After exposure to hypoxia (20% [O2] for 2 hours) individuals showed equal probability to turn right or left. Given the value for survival of behavioral lateralization (e.g. enhanced of cognitive and escaping ability) this loss in behavioral lateralization could have severe costs for individual fitness in hypoxic environments. No effect was found in the other two species, which did not show behavioral lateralization on the population level in the control treatment