Effects of Time of Day, Water Temperature, and Water Velocity on Swimming by Postlarvae of the American Lobster,Homarus americanus

Abstract

Swimming speeds and swimming behavior of laboratory-reared and wild postlarvae (larval stage IV) of the American lobster, Homarus americanus, were observed in tanks of still water and in a linear flume. Mean swimming speeds ranged from about 7 cm∙s−1in the "claws-apart" swimming mode to 13.2 cm∙s−1in the streamlined, "claws-together" mode. In the flume, the total time spent swimming during a 30-min test period decreased as water velocity increased from 8 to 14 cm∙s−1. The time spent swimming was greater during the day than at either dusk or night. Postlarvae spent very little time swimming at 15 °C but significantly more at 21 °C. Wild postlarvae were larger, heavier, and swam more rapidly than laboratory-reared postlarvae. Rapid, directional swimming by postlarval lobsters may play a role in determination of distribution and recruitment to benthic populations.