CS16 Harmful Algal Blooms
Date: Wednesday, June 12, 2002
Time: 3:15:00 PM
Location: Sidney
 
YINK, Hong Kong University of Science and Technology, Kowloon, Hong Kong POC, kyin@ust.hk
Qian, P, , Hong Kong University of Science and Technology, Kowloon, Hong Kong POC, 
Wu, M, , Hong Kong University of Science and Technology, Kowloon, Hong Kong POC, 
Kan, J, , Hong Kong University of Science and Technology, Kowloon, HONG KONG POC, 
 
DID NUTRIENTS CAUSE THE FORMATION AND DISAPPEARANCE OF THE RED TIDE OF SCRIPPSIELLA TROCHOIDEA IN PORT SHELTER
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We investigated the in-situ conditions of a red tide of S. trochoidea in a bay and conducted nutrient addition experiments on water samples from the red tide and non-red-tide patches to examine what caused formation and disappearance of the red tide. Nutrients including NO3, PO4, SiO4, NH4 and urea were all low in the surrounding waters and deep waters. Nutrients were added to waters samples from the red tide patch and the non-red-tide patch. Phytoplankton biomass decreased over 9 days in the red tide water sample without any nutrient additions and without N additions. With N additions, phytoplankton biomass increased steadily until day 7. In the non-red-tide samples, only additions of all NO3, PO4, and SiO4 produced a substantial increase in phytoplankton biomass, which consisted mostly of diatoms in the end of incubation. Low nitrogen in the surrounding and deep waters, and lack of dominance of S. trochoidea in the non-red-tide water sample enriched with all nutrients indicate that factors other than nutrients promoted the red tide formation and disappearance of this species.