Response of American lobsters Homarus americanus to infection with a field isolate of Aerococcus viridans var. homari (gaffkemia): Survival and haematology

Abstract

American lobsters Homarus americanus were inoculated with a field isolate of the Gram-positive bacterium Aerococcus viridans var. homari, causative agent of gaffkemia, at 1 × 106, 1 × 104 or 1 × 102 colony forming units (CFU) kg-1 or with sterile 3% NaCl and maintained at 10 or 15°C until they died or were euthanised. Progression of disease in individual animals was monitored daily by total haemocyte count (THC) and haemolymph culture. Post-mortem examinations were performed on all lobsters. Effects of both ambient temperature and infective dose on survival time were observed. Marked bacteraemia occurred in all mortalities. Haemocytopenia (THC < 10 × 109 cells l -1) preceded death in most, but not all, mortalities.