The effect of intrinsic and extrinsic factors like disease, nutrit-ional status, bilateral eyestalk ablation and different water exchange regimes on the total haemocyte count (THC) of the spiny lobster, Panulirus homarus was studied. The THC count reduced by 31.30, 50.34 and 72.01% in the lobsters infected by shell disease with 5-10, 10-20 and > 20% lesion cover respectively. The control healthy lobsters with 0% lesion showed the highest THC (20.07 ± 0.99× 106 cells ml-1) and the lowest was observed in the group displaying > 20% shell lesion cover (5.59 ± 0.49 × 106 cells ml-1). The serum protein reduced by 16.19, 33.27 and 55.06% respect-ively in the groups displaying 5-10, 10-20 and > 20% lesion cover. Clotting time showed a significant (p < 0.01) negative correlation with THC and serum protein. Starved lobsters and those fed with pellet diet displayed significantly (p < 0.05) lower THC and serum protein compared to lobsters fed on green mussel (Perna viridis).Bilaterally eyestalk ablated lobsters showed a higher THC and serum protein content than their unablated counterparts. The lobsters grown in different water exchange regime (25, 50, and 75% exchange) had a comparatively lower (17.38, 12.92 and 8.73%) THC and the culture water had a higher (81.86, 48.80 and 21.84%) total heterotrophic bacterial (THB) and Vibrio sp. load (86.20, 77.83 and 18.40%) than the lobsters maintained at 90% water exchange regime. The haematological para-meters like THC, serum protein content and clotting time which are altered by environmental and biological stress factors can thus be used as potential stress indicators for monitoring the health status of spiny lobsters.

Panulirus homarus, total haemocyte count, serum protein, disease, nutritional status, clotting, extrinsic, intrinsic factors