World Aquaculture Singapore 2022

November 29 - December 2, 2022

Singapore

DETERMINING NITRATE AND AMMONIA ABSORPTION RATE IN Ulva sp., Caulerpa sp., and Graciliaria sp. TO INVESTIGATE THE FEASIBILITY OF SEAWEED CO-CULTURE IN RECIRCULATING AQUACULTURE SYSTEM

Lee. Z.* and Mei. A.

Diploma in Veterinary Technology, School of Applied Science, Temasek

Polytechnic, Singapore 529757

1703725J@tp.edu.sg

 



Three species of seaweed, Ulva sp., Caulerpa sp., and Gracilaria sp., were cultivated in tanks after acclimatization in an indoor culture for about 2 weeks each with calculated doses of nutrients at 2ppm representing low concentration and 8ppm as a representation of high concentration of nutrients. The nutrients absorption rate was determined through the series of nutrient trials and during the nutrient trials it showed that the Gracilaria sp., and Ulva sp., managed to absorb all the nutrients throughout the two weeks of the nutrient trial and showed a positive growth rate. However, the Caulerpa sp., although managed to absorb the all the nutrients for ammonia and generally did absorb nutrients throughout, slowly depleting the nutrients present in the tank, it was seen that other than the tanks with low concentration of ammonia, there was a negative growth rate for the Caulerpa sp., on average for the other three nutrient concentrations. This will then be used to determine the nutrient absorption rates of the various seaweed species and be used for the calculation of stocking density of seaweed required to implement the seaweeds into a co-culture in a recirculating aquaculture system as a bio-filter to investigate the feasibility of a co-culture. The results of this study showed that the nutrients may not be a direct factor influencing the growth rate of the seaweed species due to the amount of growth in absorption of high concentration of nutrient in Ulva sp., was observed with slower growth of the Ulva sp.