Rotifer Growth Under Astaxanthin Enrichment

Abstract

Rotifers and astaxanthin both play an important part in the aquaculture industry. Rotifers are used as a substitute for copepods, the main source of food for larval fish in natural systems, due to the ease with which they can be cultured. Astaxanthin is a carotenoid and antioxidant which brightens the coloring of fish and improves fish health. Rotifers are believed to be a method through which astaxanthin can be bioencapsulated and vectored to larval fish. As a result, it is important to understand the effect of astaxanthin on rotifers themselves. This experiment uses a multitude of different protocols to determine how different astaxanthin compounds effects rotifers on both the individual and population levels. Reproductive tables and fluorescent imaging were used to assess the health of individual rotifers; population density measurements in mass cultures were used to assess rotifer population health. The reproductive ability of rotifers was significantly different from control under multiple astaxanthin treatments. Astaxanthin enrichment also created a higher stable population density in the mass cultures. The fluorescent imaging showed that the rotifers reached peak astaxanthin concentration within the rotifer gut after 3 hours, and but concentration returned to control levels within 24 hours of removal from astaxanthin. These results all point to the fact that astaxanthin helps to increase rotifer health and fitness, and that these rotifers could be used as a vector for astaxanthin to larval fish.