不同氮源对4种海洋微藻生长的影响

采用实验室一次性培养的方法,研究了硝氮、氨氮、尿素和混合氨基酸等4种不同氮源对典型赤潮藻赤潮异弯藻Heterosigma akashiwo、凯伦藻Karenia sp.、球形棕囊藻Phaeocystis globosa和常见浮游植物优势种类角毛藻Chaetoceros sp.生长的影响。结果表明,这4种海洋微藻不仅能利用无机氮硝氮和氨氮,而且也均能利用有机氮尿素和混合氨基酸。赤潮异弯藻、凯伦藻和角毛藻均在以硝氮为唯一氮源时,比生长速率分别达到最大值0.45、0.52和0.70 d-1;而球形棕囊藻在以硝氮和尿素为唯一氮源时,比生长速率均达最大值0.65 d-1。可溶性有机氮库中的重要组成成分尿素和氨基酸均能显著促进4种海洋微藻的生长;相比较而言,赤潮异弯藻和凯伦藻更加喜好有机氮氨基酸,而球形棕囊藻和角毛藻更加喜好尿素。海洋微藻具备利用有机氮源的能力,无疑扩展了其氮营养来源,在无机氮缺乏而有机氮丰富的水体中,它们在浮游植物群落中更具有竞争优势。

Effects of nitrogen sources on the growth of Heterosigma akashiw,Karenia sp.,Phaeocystis giobosa and Chaetoceros sp.

Growth characteristics of four bloom-forming microalgae,Heterosigma akashiwo,Karenia sp.and Phaeocystis globosa,and one common dominant species Chaetoceros sp.isolated from the coastal waters of China were studied in the laboratory with nitrate,ammonium,urea and amino acid mixture provided as the sole nitrogen source respectively.All the four species were able to utilize both dissolved inorganic nitrogen forms as nitrate and ammonium and dissolved organic nitrogen substrates as urea and amino acid.The maximum specific growth rates of H.akashiwo,Karenia sp.and Chaetoceros sp.were 0.45,0.52 and 0.70 d-1 respectively when nitrate as their sole nitrogen source.When nitrate and urea were provided as sole nitrogen substrates,P.globosa exhibited the same maximum specific growth rate 0.65 d-1.As fundamental components of dissolved organic nitrogen,urea and amino acid could significantly stimulate the growth of H.akashiwo,Karenia sp.,P.globosa and Chaetoceros sp..The results showed that among organic nitrogen sources,H.akashiwo and Karenia sp.preferred to amino acid,but P.globosa and Chaetoceros sp.urea.The ability to utilize urea or amino acid as the sole nitrogen source may broaden their nitrogen sources,and enhance the competition potential for H.akashiwo,Karenia sp.,P.globosa and Chaetoceros sp.in the environment at lower availability of inorganic nitrogen sources.