Effect of crude extracts of Dolichospermum planctonicum on the demography of Plationus patulus (Rotifera) and Ceriodaphnia cornuta (Cladocera).

In this study we evaluated the toxicological effects of crude extracts of Dolichospermum planctonicum on Plationus patulus (Rotifera) and Ceriodaphnia cornuta (Cladocera). The active compound from the laboratory-cultured cyanobacteria was extracted by lyophilizing it at -70 °C for 48 h, after which the sample was thawed. The cycle was repeated five times, and between each cycle the cells were sonicated to lyse them. Using the extract of Anabaena, experiments of population growth and life table demography of the two zooplankton species were compared in media with and without (controls) the cyanotoxins. In both experiments two toxic concentrations diluted in US EPA medium were used, one in a 5:15 proportion, and the other in a 2.5:17.5. We found that the rotifers were more resistant to the toxicants than the cladocerans. Their population growth rates ranged from 0.11 d(-1) in controls to 0.08 d(-1) in the presence of the crude extracts for P. patulus and from 0.18 in controls to -0.27 in the presence of the crude extracts for C. cornuta. The crude extract also had a significant negative impact on the demographic parameters, adversely affecting reproduction more than survival. The data have been discussed with emphasis on the importance of further research using cyanobacterial crude extracts.