Isolation and culture of the marine rotifer, Colurella dicentra (Gosse, 1887), from a Mississippi Gulf Coast estuary

Few marine rotifer species (e.g. Encentrum linheii and Synchaeta cecilia) have been cultured successfully besides Brachionus plicatilis and B. rotundiformis, commonly used to rear larvae of many marine fish species. The development of culture techniques for marine rotifers smaller in size than the Brachionus species may be useful for rearing fish species for which the currently used prey are too large. We evaluated the possibility of culturing Colurella dicentra isolated from a Mississippi Gulf Coast estuary. An experiment was conducted to determine the effects of salinity (10–35 g L^?1) on its population growth rate. Rotifers were fed Nannochloropsis oculata at a density of 100 000 cells mL^?1 for 15 days. Colurella dicentra survived in water with a salinity of 10–47 g L^?1. Densities of up to 300 rotifers mL^?1 were sometimes attained in cultures. Salinity influenced C. dicentra production (P<0.001). The mean rotifer numbers at 10 g L^?1 (22 840±2604 SD), 15 g L^?1 (25 980±7071 SD) and 20 g L^?1 (19 780±1029 SD) at the end of the experiment were similar (P>0.05), but were higher (P=0.05) than numbers at 25 g L^?1 (4240±1783), 30 g L^?1 (1300±264 SD) and 35 g L^?1 (100±101 SD). The population growth rate (r) of the rotifers was the highest at 15 g L^?1 (0.37–0.42 day^?1), and the lowest at 35 g L^?1 (?0.33–0.06 day^?1). This is the first report of C. dicentra in the estuarine waters of the Gulf of Mexico, and also the first time it has been cultured successfully.