Environmental Hypoxia Reduces the Escape Response Capacity of Juvenile and Adult ScallopsArgopecten purpuratus

Abstract

ABSTRACT Natural beds and cultures of the scallop Argopecten purpuratus are exposed to hypoxia periodically because they are located near upwelling zones. We evaluated the effects of environmental hypoxia on juvenile and adult scallops' escape responses and recovery capacities using 3 different hypoxic cycle (i.e., a gradual decrease and increase of dissolved oxygen) trials. Trials 1 and 2 consisted of single (1-day) hypoxic cycles; trial 3 included exposure to several consecutive daily hypoxic cycles over 7 days, which occurs in the natural environment. Trial 1 evaluated the combined effects of energy demands from escape responses and metabolism on escape responses. during environmental hypoxia. Trial 2 evaluated only the effect of environmental hypoxia on the escape responses. Before and after the hypoxic cycles, the scallops were exposed to their main predator, the sea star Meyenaster gelatinosus. We evaluated 6 indicators of the scallops' escape response: reaction time, the total number of claps, dura...