Submitted to: Book of Abstracts U.S. Chapter of World Aquaculture Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/28/2002
Publication Date: 1/28/2002
Citation: PFEIFFER, T.J., LUDWIG, G.M. TURBIMETRIC AND NUMERIC METHODS FOR ESTIMATING THE DENSITY OF A CULTURED ROTIFER POPULATION.. BOOK OF ABSTRACTS U.S. CHAPTER OF WORLD AQUACULTURE SOCIETY. 2002. p.264.
Technical Abstract: The objective of this research was to obtain a practical solution to estimating the number of rotifers in a cultured population. Rotifers (Brachionus plicatilis) were cultured in 60-L translucent polyethylene tanks that contained hydrosponge filters for biofiltration and solids collection. Culture volume was 45-L. A feed solution of the algae Nannochloroposis and salt water was pumped from 2.5-L chilled containers to the culture at the rate of 100 mL per hour. Culture water was 25 ppt artificial sea salt mixed with filtered tap water. Daily the tanks were purged of settled material and wiped to prevent biofilm development. Dissolved oxygen and ammonia concentrations, pH and temperatures were determined daily as were rotifer counts. Fifteen liters of culture water were harvested whenever the estimated rotifer concentration exceeded 1500 rotifers/mL. Cultures were sustained between ten and twenty-one days during the trial periods. Feed concentrations between 25,000 and 150,000 algal cells per rotifer per day were provided to determine the optimum concentration for sustainable rotifer growth and suitable water quality. Numbers of rotifers within a 1-mL Sedgewick-Rafter counting cell for three samples were averaged to determine rotifer density. Culture turbidity of the rotifer population was determined with a portable turbidimeter. The net turbidity of the culture was correlated with the mean count of the replicated samples. The correlation indicated turbidity to be an affordable and practical solution for rapid estimation of rotifer population and a potential method for incorporation to an automated feeding process.