The potential of the planctomycete Rhodopirellula rubra strain LF2 was evaluated as a nutritional or a supplementary food source for D. magna and D. longispina

Daphnids showed impairment in all the parameters of life history evaluated specially when only fed with R. rubra

Daphnids were fed with algae and planctomycetes no alterations were recorded for the rate of population increase.

In the concentrations tested, R. rubra was not a good alternative food source in daphnids diet.