Article info.

ABSTRACT

Received 17 Oct 2016
Revised 21 Apr 2017

Accepted 31 Oct 2017

      This study was conducted to determine the effects of different pH values on the flocculation efficiency of Chaetoceros calcitrans and using flocculated algae as diet for nursing sweet snail (Babylonia areolata) larvae. In the 1^st experiment, C. calcitrans were flocculated by chitosan at three pH levels as follows: (1) control (maintaining at pH=9.0); (2) adjusted to 7.0 and (3) adjusted to 5.0. In the 2^nd experiment, flocculated algae were stored at temperature of 4^oC in 15 days to determine the viability and ability to grow after re-inoculation. In the 3^rd experiment, flocculated algae were used for feeding sweet snail larvae in 20 days. Algae flocculation reached the highest efficiency (91%) after 4 hours at pH 5.0. At control pH treatment (pH 9.0) C. calcitrans obtained highest cell viability (52.23%). After re-inoculation at initial density of 500,000 cells/mL, the highest cell density was obtained at day 15 in pH 7 (8,750,000 cells/mL). After 20 days feeding with different flocculated C. calcitrans, the sweet snail larvae in control pH obtained not only highest survival rate (72.52%) but also the highest shell length and height (1938.89 and 1041.67µm, respectively). The findings indicated that it was necessary to remain pH value from 7.0-9.0 in order to obtain the high algal cell viability after flocculation with chitosan and effectiveness for using as diet for sweet snail larvae.

Keywords

Babylonia areolata larvae, cell viability, Chaetoceros, chitosan, flocculation

Cited as: Thao, N.T.T., Hanh, T.T.N. and An, D.T.T., 2017. Flocculation efficiency and quality of flocculated algae with chitosan at different pH values. Can Tho University Journal of Science. 7: 65-73.