The role of nitrogenous nutrients in the occurrence of harmful algal blooms caused by Cochlodinium polykrikoides in New York estuaries (USA)

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• 作者：Christopher J. Gobler^a ; ^{Christopher.gobler@sunysb.edu} ; ^{cgobler@notes.cc.sunysb.edu} ; Amanda Burson^a ; ¹ ; Florian Koch^a ; Yingzhong Tang^a ; Margaret R. Mulholland^b
• 关键词：Eutrophication ; Nitrogen ; Harmful algal blooms ; Cochlodinium polykrikoides ; Dinoflagellates
• 刊名：Harmful Algae
• 出版年：2012
• 出版时间：May, 2012
• 年：2012
• 卷：17
• 期：Complete
• 页码：64-74
• 全文大小：799 K

文摘

The harmful dinoflagellate Cochlodinium polykrikoides is well known for forming ichthyotoxic blooms around the world, but the nutritional factors supporting and promoting these blooms have not been well studied. To better understand the nitrogen (N) nutritional ecology of C. polykrikoides, the temporal and spatial dynamics of nutrients, C. polykrikoides cells, and co-occurring phytoplankton were monitored within multiple NY (USA) estuaries over a three-year period. Uptake rates of bicarbonate and various N compounds were assessed during blooms and the growth responses of C. polykrikoides relative to co-occurring phytoplankton were quantified during N enrichment bioassays. Finally, the growth kinetics of C. polykrikoides were examined using clonal cultures grown on four N sources (ammonium, glutamic acid, nitrate, urea). Blooms of C. polykrikoides occurred when concentrations of nitrate and ammonium were <2 ¦ÌM but dissolved organic N levels were high (>20 ¦ÌM). During blooms, the addition of N compounds (ammonium, glutamic acid, nitrate, or urea) significantly enhanced primary productivity among microphytoplankton (>20 ¦Ìm; p < 0.05) and significantly increased the net growth of C. polykrikoides relative to other phytoplankton groups (p < 0.05), suggesting blooms were N-limited. The dominant N compounds assimilated by communities dominated by C. polykrikoides (90 % of cells) within eutrophic tributaries were nitrate and nitrite while in mesotrophic, open estuarine regions, urea and glutamic acid dominated N uptake. Finally, C. polykrikoides cultures grown on glutamic acid displayed significantly faster growth rates than cultures grown on urea, ammonium, and nitrate (p < 0.05). The sum of these observations indicate that N strongly influences C. polykrikoides blooms and that this alga is nutritionally flexible, capable of adapting to differing nutrient regimes and utilizing a variety of N compounds over a range of concentrations to form blooms.