The Studies On Ingestion, Reproduction And Population Dynamics Of Brachionus Plicatilis

Brachionus plicatilis is one of common rotifer species in marine, and is considered to have important status in material cycle and energy transportation in marine ecosystem, and applied value in aquaculture.The experiment was conducted in the ecological laboratory of the ocean university of China by using Brachionus plicatilis and a few kinds of different microalages. The effects of food type, food concentration on ingestion, and reproduction and the changes of population quantity of Brachionus plicatilis were studied in this article. The main contents and results were presented as following:1.The results from ingestion experiment of Brachionus plicatilis showed that (l)There is a close correlation between the food concentration and filtering rates (F,ml.ind~-1.h~-1), grazing rates(G,cells.ind~-1.h~-1) within the proper concentration range for Brachionus plicatils . G tended to increase in optimal food concentration range, beyond this range, G began to decrease. But F always decreased with the increase of food concentration. (2) Brachionus plicatils were able to select optimal algae from mixed food .The algae with the highest G must not be the most optimal one. the result from the selective experiment showed that the optimal kind of food ingested by Brachionus plicatils is Chlorella sp.2. Brachionus plicatils were respectively cultivated by using Chlorella sp, Isochrysis galbana Parke ,Nitaschia closterium minutissima Allen et Nelson, Paviova viridis Tseng Chen et Zhang, Chaetoceros affinis, Tetraselmis chuii. The results showed that effects of different algaes on reproduction of rotifer were different. Chaetoceros affinisas dietary canrestrain reproduction of rotifer, but chlorella, platymonasaccelerate it. Putting in algaes in differently physiological conditions leads to different results. Putting in the increasest age is suprior to that in the senile stage .The experimental so showed that rotifer reproducted largely in proper ensuring of dietary, but low or hign dietary ensuring was not good for reproduction of rotifer.3. The developmental periods and population growth characters of the rotifer Brachionus plicatils were studied under different food concentrations, to present basic data for revealing the relationship between the rotifer and its algal food environment. The experiment was conducted using population accumulative culture method. The anlmais were fed on Chlorella sp using seven concentrations(0. IX 106,0. 5X 106,1.0 X 106,2.0 X 106,4.0 X 10\8.0 X 106,12 X 106cells/ml). Food concentrations showed significant effects on embryonic and juenile development periods, duration of reproduction, umber of eggs per female.net reproductive rate, generation time and population innate rate of increase. Then umber of eggs per female, net reproductive rate, generation time and population innate rate of increase showed peak values at the food concentration of 2. OX 106cells/ml, while the juvenile development time and generation time were shortest in the group .Further more, Brachionus plicatils could keep relatively high population growth rate in a wide rang of food concentrations, showed a potential to tolerate higher algal concentration.