GULFWEED SARAGASSUM HORNERI IS AN ALTERNATIVE DIET FOR AQUACULTURE OF JUVENILE SEA URCHINS STRONGYLOCENTROTUS INTERMEDIUS IN SUMMER  

Food shortage of kelp is one of the most serious concerns for aquaculture of juvenile Strongylocentrotus intermedius in summer. For the first time, the present study provides a cost-effective approach to addressing this problem. We found S. intermedius fed gulfweed Sargassum horneri had significantly higher food consumption and better growth than those fed kelp Saccharina japonica. In addition, S. intermedius fed a combined diet of S. horneri and S. japonica showed significantly larger test diameter, test weight, body weight and higher specific growth rate than those fed S. japonica alone, but not significantly larger or higher than those fed S. horneri alone. According to the present study, partial (at least half) and total replacements of S. japonica with S. horneri are both acceptable for juvenile S. intermedius aquaculture in summer. Therefore, we suggest aqua-farmers choose total or partial replacement according to their local availability and cost of S. horneri and S. japonica in summer.