Growth and Gonad Changes in Stony Sea Urchin, Paracentrotus Lividus (Lamark, 1816) Fed Artificially Formulated Feed and Benthic Macrophyte Diet

摘要

This study reported the efficiency of artificially formulated feed and benthic macrophyte diet on growth and gonad development of cultured stony sea urchin, Paracentrotus lividus (Lamark, 1816). An initial sample of 720 individual urchins was gathered in coastal area of SE Adriatic, near Dubrovnik, Croatia and for the purposes of the experiment, was held in a flow-through system. Sea urchin were fed four test diets A, B, C and D. Diet A consisted of seaweeds collected in the natural habitat of sampled sea urchin, artificial diets B, C, and D contained a different ratio of ingredients. The feed mixtures differed in respect to corn meal content; B (22%), C (30%) and D (35%) as well as the distribution of fish meal content; B (15%), C (5%) and D (0%). Prior to the commencement of feeding, sea urchins in all groups were starved for 15 days. During the period of starvation, recorded total urchin weight, gonadosomatic index (GSI) and gonad weight values for all experimental groups, showed a declining trend except in the control group, where they stayed the same. After 30 days, the declining trend of morphometric values was recorded for treatment A and the control group. During the two months of the intensive feeding conditions in the regimes with artificially prepared feed, B, C and D a growing trend was recorded for all morphometric values, and it was particularly evident in the treatment C. In the last month of the experiment, a significant decline in the GSI and gonad weight values were observed for the groups, A and the control. The differences among the artificially formulated feeds expressed through increase of GSI and gonad mass values revealed that the best among them was artificial feed C whose variance in consistence of essential nutritional components fits between prepared feeds B and D. Based on the results of our study we conclude that the artificially formulated feed is adequate food for sea urchins in a controlled environment, especially when it contains a smaller animal protein component (5- 10%) and a larger share of plant components (over 90%).