Substrate Preference Behavior of Juvenile American Lobsters, Homarus americanus, in Gravel and Silt–Clay Sediments

In the laboratory, early stage juvenile American lobsters, Homarus americanus, showed a preference for spending time and selecting shelters in gravel when given a choice between silt–clay deposited over gravel versus gravel substrates. Lobsters excavated shelters in the gravel by various combinations of pushing, plowing, and carrying stones with their chelae, third maxillipeds, and walking legs. Burrows in silt–clay were invariably adjacent to supporting structures. Our observations on shelter modifications and occupancy indicate that juvenile lobsters are active primarily, but not exclusively, at night. The juvenile lobsters frequently changed shelters during the initial 3 d before a status quo was established. We hypothesize that ocean dumping of silt–clay over gravel may increase spatial competition among juvenile lobsters for shelter in remaining gravel habitat.