Automatic measurement of Acartia tonsa nauplii density, and estimation of stage distribution

Copepods are increasingly seen as an important feed in the culture of marine fish. Calanoid species such as Acartia tonsa have been studied for mass culture purposes. In this work, a plankton counter developed for automatic measurement of density in rotifer (Brachionus plicatilis) cultures has been tested for Acartia nauplii. The plankton counter, after adaptation, can estimate both the size and density of the nauplii within reasonable margins of error. Size estimates were validated against measurements made by microscope, and density estimates against manual counts.
The plankton counter makes it possible to automatically monitor metrics like hatching success, mortality and development rate in Acartia cultures, as well as monitoring of densities in larval first feeding tanks. The latter opens the opportunity for appetite based feeding of larvae. The area measurement can be used to estimate the biomass and the development stage of the nauplii.