Genetic identification and comparative study on life history parameters of two strains belonging to Brachionus plicatilis species complex (Rotifera: Monogononta)

Abstract

The rotifer Brachionus plicatilis is an important species for aquaculture, due to its use as food for bivalves, and fish and crustaceans larvae in hatcheries. However, being a species complex, it has become increasingly important to catalogue and describe the species and biotypes that constitute this complex. Therefore, the purpose of this study was to genetically identify two morphologically identical strains and evaluate their suitability to be used in aquaculture under the studied conditions. A correct identification and knowledge of life history characteristics of the biotypes and isolated strains is vital to avoid mass mortalities in aquaculture and to better interpret the responses of the organisms when these are used as a bioindicator and model for ecotoxicology. Strains MRS10 and IBA3 were identified as B. koreanus and, even though they have been maintained under the same laboratory conditions for several years, significant differences in several life history parameters were observed. A life table assay showed IBA3 rotifers to be larger at first reproduction, and to have longer post-reproductive period and mean lifespan. On the other hand, MRS10 rotifers produced less non-viable eggs and had higher population growth rate. Both strains showed to be a potential model for ecotoxicological and molecular studies, mainly due to the ease of maintenance, short generation time, and reproduction via parthenogenesis. However, MRS10 might present better characteristics than IBA3 to be reared in aquaculture as live food.

Keywords

• 16S rRNA gene
• Aquaculture
• Cryptic species
• Ecotoxicology
• Fecundity and lifespan
• Intrinsic rate of population growth