The effects of alkalinity on production performance and biochemical responses of spiny lobster Panulirus homarus reared in a recirculating aquaculture system

Spiny lobsters (Panulirus sp.) were valuable and one of the most popular Indonesian export commodities. Some approaches were made to increase the quantity and quality of cultivated spiny lobsters. Land-based mariculture with Recirculating Aquaculture System (RAS) was applied to increase lobster harvesting and optimize environmental quality by adjusting water alkalinity. This study aimed to determine the optimum level of alkalinity for spiny lobsters Panulirus homarus rearing in RAS. This study investigated the effects of applying four water alkalinity levels (Control, 125, 200, and 275 mg L-1 CaCO3) on the biochemical responses of P. homarus observed in the hemolymph in terms of Total Hemocyte Count (THC), glucose, total protein, calcium, and pH levels. Furthermore, we also studied the alkalinity effects on lobster production performance parameters in terms of body weight gain, body length, Survival Rate (SR), Specific Growth Rate (SGR), and Feed Conversion Ratio (FCR). Lobsters with an initial weight rate of 58.05 +/- 1.69 g and an initial total length rate of 115.33 +/- 1.52 mm were reared for 60 days in a recirculation system. Results of water quality parameters such as ammonia, nitrite, nitrate, dissolved oxygen, temperature, and salinity during the study were available for lobster rearing. Different alkalinity levels affected the biochemical responses and production performance of lobsters. The best alkalinity level to reared Panulirus sp. in the recirculation system during this study was 200 mg L-1 CaCO3 so that it could achieve the highest survival rate of 86.67% with SGR 0.60 +/- 0.01 % day(-1).