Low pH avoidance by crayfish (Orconectes virilis): evidence for sensory conditioning

Abstract

Avoidance responses of crayfish (Orconectes virilis) to low pH were tested for individuals from two populations, one inhabiting a reference lake and one from a lake experimentally acidified over a 5-year period to a mean summer epilimnetic pH of 5.3. Adult and yearling crayfish from the reference population displayed a strong avoidance of potentially lethal water of pH 4.5 and below. However, there was no avoidance demonstrated to water above pH 5.0, which is known to seriously impair reproduction of this species. Animals from the acidified lake had noticeably reduced avoidance, significant at only pH 4.0, with no behavioral modification occurring above pH 4.5.