Hemolymph clotting time as an indicator of stress in western rock lobster ( Panulirus cygnus George)

Abstract

A simple method to measure clotting time was introduced in an experiment studying the effects of exercise stress on western rock lobster ( Panulirus cygnus). The treatment group lobsters ( N=8) were made to exercise (tail flipping) in a 200 l tank for 2 min. Lobsters were then sampled immediately after exercise and once again 1 h later. Controls were sampled both before the experiment started and after all the other samples were taken (pre- and post-exercise controls). Total hemocyte counts (THCs), differential hemocyte counts (DHCs), hemolymph clotting time, hemolymph protein content and lobster vigor were analyzed. THCs, DHCs, hemolymph clotting and vigor index showed response to treatment. THCs were increased significantly 1 h after exercise (6.36±0.58×10 6 cells/ml) compared to pre- and post-exercise controls (4.42±0.38 and 4.41±0.38×10 6 cells/ml, respectively). Hemolymph clotting time in the same experimental lobsters (43.7±2.0 s) were decreased compared to pre- and post-exercise control groups (56.0±4.1 and 52.7±2.2 s, respectively). Hemolymph clotting times were correlating with DHCs and hemolymph protein levels. Hemolymph clotting time is easily measured and could be a useful indicator of stress.