Use of the shuttle box system to determine the effects of hypoxia and food deprivation on the behavioral responses of the rock crab Cancer irroratus Say, 1817 (Decapoda: Brachyura: Cancridae)

Abstract

Food-deprivation state (fed, fasted, starved) affected rock crabs physiological and biochemical responses to hypoxia in Cancer irroratus. Fasted and starved crabs were better adapted to deal with hypoxia than fed animals; however, avoidance behavior is usually considered as the first defense to environmental stressors for decapod crustaceans. We examined the effects of food deprivation on the crab’s behavior to hypoxia using the Loligo® shuttle box system, an automated system with a pair of connected water chambers with regulated flow and oxygen level. Crabs (starved, fasted and fed) that were offered a choice of two different oxygen saturations did not appear to actively avoid the hypoxia regimes tested (50% and 20% oxygen saturation). We used novel algorithms to analyze the data and found that crabs altered rheotaxis (movement towards or away from a current of water) and corresponding moving speed as a function of oxygen saturation. The food-deprivation state did influence thigmotaxis (contact with walls/objects when exploring an open space): starved crabs became bolder and more likely to explore open areas of the apparatus. Technological advancements such as the fully automated shuttle box have improved our ability to collect and analyze behavioral data; however, our study also highlighted some of the potential problems of relying solely on such apparatus to study the behavior of benthic crustaceans.