TY - JOUR
T1 - Effects of inorganic and organic nitrogen and phosphorus on the growth and toxicity of two Alexandrium species from Hong Kong
AU - Xu, Jie
AU - Ho, Alvin Y.T.
AU - He, Lei
AU - Yin, Kedong
AU - Hung, Craig
AU - Choi, Nicola
AU - Lam, Paul K.S.
AU - Wu, Rudolf S.S.
AU - Anderson, Donald M.
AU - Harrison, Paul J.
N1 - Funding Information:
Financial support for this research was provided by the University Grants Council of Hong Kong AoE project (AoE/P-04/04-4-II) and the Central Allocation Group Research Projects funded by the Research Grants Council of Hong Kong . We thank the Agricultural, Fisheries and Conservation Department (AFCD) of Hong Kong Government Hong Kong Government AFCD for providing us with the stock cultures of Alexandrium tamarense. DMA received partial funding through the NSF/NIEHS Centers for Oceans and Human Health (grants NIEHS P50 ES012742 , NSF OCE-043072 and OCE-0911031 ), through NSF grant OCE-0850421 , and by the ECOHAB program (NOAA Grant NA06NOS4780245 ). This is contribution number 680 from the ECOHAB program.[TS]
PY - 2012/4
Y1 - 2012/4
N2 - The effects of three nitrogen (N) and two phosphorus (P) inorganic and organic forms on the growth, toxin content and composition, toxin production, and chemical composition of Alexandrium catenella and Alexandrium tamarense isolated from coastal waters of Hong Kong were determined. The toxin production rate and cellular toxin content for A. catenella were at least 10-fold higher than A. tamarense. The highest net production rate (Rtox) of the two Alexandrium species was generally achieved in the exponential phase. However, the highest cellular toxin content occurred in the stationary phase in all cultures, partly due to the enhancement of cell volume caused by P limitation, except for urea grown cultures where cellular toxin content remained low throughout the growth stage. For A. catenella, NH4 induced the highest growth rate (0.59d-1), toxin production rate (μtox, 1.0μmolL-1d-1; Rtox, 2.5pmolcell-1d-1) and cellular toxin content (2.8pmolcell-1) among the three nitrogen sources regardless of inorganic and organic P. The form of phosphorus had limited effect on A. catenella. In contrast, the response of A. tamarense to different forms of nitrogen and phosphorus was more complex. NH4 induced the highest cellular toxin content (445fmolcell-1), while NO3 yielded the highest toxin production rate (μtox, 0.71nmolL-1d-1; Rtox, 140fmolcell-1d-1) and urea produced the highest growth rate (0.57d-1). For A. tamarense, the highest toxin production rate occurred under organic phosphorus. The relationship between toxin accumulation and the form of nitrogen varied with the phosphorus source. A. catenella cultures grown on NO3 and NH4 have about 80-90% C1/2 toxins and 5-15% GTX 1/4 toxins compared to 65-75% C1/2 toxins and 25-35% GTX 1/4 toxins in cultures grown on urea. Our results suggest that during summer when Alexandrium uses NH4 from local sewage effluent as its preferred nitrogen source, it might become more toxic in combination with episodically occurring P limitation in Hong Kong waters.
AB - The effects of three nitrogen (N) and two phosphorus (P) inorganic and organic forms on the growth, toxin content and composition, toxin production, and chemical composition of Alexandrium catenella and Alexandrium tamarense isolated from coastal waters of Hong Kong were determined. The toxin production rate and cellular toxin content for A. catenella were at least 10-fold higher than A. tamarense. The highest net production rate (Rtox) of the two Alexandrium species was generally achieved in the exponential phase. However, the highest cellular toxin content occurred in the stationary phase in all cultures, partly due to the enhancement of cell volume caused by P limitation, except for urea grown cultures where cellular toxin content remained low throughout the growth stage. For A. catenella, NH4 induced the highest growth rate (0.59d-1), toxin production rate (μtox, 1.0μmolL-1d-1; Rtox, 2.5pmolcell-1d-1) and cellular toxin content (2.8pmolcell-1) among the three nitrogen sources regardless of inorganic and organic P. The form of phosphorus had limited effect on A. catenella. In contrast, the response of A. tamarense to different forms of nitrogen and phosphorus was more complex. NH4 induced the highest cellular toxin content (445fmolcell-1), while NO3 yielded the highest toxin production rate (μtox, 0.71nmolL-1d-1; Rtox, 140fmolcell-1d-1) and urea produced the highest growth rate (0.57d-1). For A. tamarense, the highest toxin production rate occurred under organic phosphorus. The relationship between toxin accumulation and the form of nitrogen varied with the phosphorus source. A. catenella cultures grown on NO3 and NH4 have about 80-90% C1/2 toxins and 5-15% GTX 1/4 toxins compared to 65-75% C1/2 toxins and 25-35% GTX 1/4 toxins in cultures grown on urea. Our results suggest that during summer when Alexandrium uses NH4 from local sewage effluent as its preferred nitrogen source, it might become more toxic in combination with episodically occurring P limitation in Hong Kong waters.
KW - Alexandrium
KW - Cell volume
KW - Gonyautoxins
KW - Nutrients
KW - Paralytic shellfish toxins
KW - Toxic dinoflagellates
KW - Urea
UR - https://www.scopus.com/pages/publications/84862779619
U2 - 10.1016/j.hal.2012.02.006
DO - 10.1016/j.hal.2012.02.006
M3 - Article
AN - SCOPUS:84862779619
SN - 1568-9883
VL - 16
SP - 89
EP - 97
JO - Harmful Algae
JF - Harmful Algae
ER -