摘要
Diatom blooms in Thau lagoon are always related to rain events leading to inputs of inorganic nutrients such as phosphate, ammonium and nitrate through the watershed with time lags of about 1 week. In contrast, blooms of Alexandrium catenella/tamarense can occur following periods of 3 weeks without precipitation and no significant input of conventional nutrients such as nitrate and phosphate. Field results also indicate a significant drop (from 22–25 to 15–16 μM over 3 days) in dissolved organic nitrogen (DON) at the bloom peak, as well as a significant inverse relationship between A. catenella/tamarense cell density and DON concentrations that is not apparent for diatom blooms. Such dinoflagellate blooms are also associated with elevated (6–9 μM) ammonium concentrations, a curious feature also observed by other investigators, possibly the results of ammonium excretion by this organism during urea or other organic nitrogen assimilation.
The potential use of DON by this organism represents short cuts in the nitrogen cycle between plants and nutrients and requires a new model for phytoplankton growth that is different from the classical diatom bloom model. In contrast to such diatom blooms that are due to conventional (nitrate, phosphate) nutrient pulses, Alexandrium catenella/tamarense blooms on the monthly time scale are due to organic nutrient enrichment, a feature that allows net growth rates of about 1.3 d−1, a value higher than that generally attributed to such organisms.
摘要译文
在Thau泻湖硅藻水华总是与降雨导致无机养分如磷酸盐，通过流域铵态氮和硝态氮输入，时间滞后了约1周。相比之下，链状亚历山大藻华的/藻可能会出现以下3周无降水时段和常规营养素，如硝酸盐和磷酸盐没有显著输入。现场结果还表明显著下降（从22-25到15-16catenella /藻细胞密度和DON浓度是看不出来的硅藻大量繁殖。这种甲藻大量繁殖也与相关的升高（6-9一个奇怪的特点也被其他研究者，铵排泄可能的结果通过这种微生物尿素等有机氮同化过程中观察到。DON这个有机体代表捷径植物和营养物质的氮循环，并要求对浮游植物生长的新模式，它是从传统的硅藻水华模式不同。与这样的硅藻大量繁殖是由于常规（硝酸盐，磷酸盐）营养脉冲在每月的时间尺度链状亚历山大藻/藻大量繁殖是由于有机养分富集功能，该功能允许约1.3ðSUP净值增长率值比一般归因于这类生物体更高。
Yves Collos[a]; Cécile Jauzein[a]; Widya Ratmaya[b]; Philippe Souchu[c]; Eric Abadie[d]; André Vaquer[a]. Comparing diatom and Alexandrium catenella/tamarense blooms in Thau lagoon: Importance of dissolved organic nitrogen in seasonally N-limited systems[J]. Harmful Algae, 2014,37: 84–91