Dissolved Organic Nitrogen and Brown Tide Blooms in Long Island Coastal Waters

自1985年以来，“褐潮”单细胞藻类（Aureococcus anophagefferens）的水华在长岛东部沿海沃茨零星发生，并破坏了当地的商业扇贝渔业。10年的时间序列数据集从佩科尼克河口的分析表明，水华强度与高硝酸盐地下水的排放量呈负相关，并与较高的盐度。实验室和现场数据表明，盐度不太可能代表褐潮水华的直接生理控制。然而，预算计算表明，氮供应从地下水是1 - 2个数量级高于其他外部来源的生态系统。1995年收集的数据表明，褐潮水华利用溶解有机氮（DON）的增长证明了从大量减少DON与细胞的增加平行。我们假设，水华的开始是由无机和有机氮的相对供应，确定在很大程度上由地下水流量的变化。检验这一假设的适当的第一步是证明DON中存在可以被A.这使它比其他特有物种具有竞争优势。我们将确定A可获得的DON的来源。通过田间和实验室研究确定了嗜食性果蝇。实验室工作将涉及识别的DON组件从Peconic河口，可以支持的DON的吸收系统和利用机制，使这种竞争力，利用氮的增长和表征。将制备涉及DON利用的主要蛋白质的免疫探针。在该领域中，我们将表征A.在水华期间，以及使用免疫探针跟踪这种藻类的氮营养。每周一次的营养物生物测定和对各种溶解氮和颗粒氮库的分析将补充更详细的实地取样。

Blooms of the `Brown Tide` unicellular algae (Aureococcus anophagefferens) have occurred sporadically since 1985 in coastal waters of Eastern Long Island and have devastated the local commercial scallop fishery. Analysis of a 10 year time series data set from the Peconic Estuary indicates that bloom intensity is inversely correlated with the discharge of high nitrate groundwater and associated with higher salinities. Laboratory and field data suggest that salinity is unlikely to represent a direct physiological control on Brown Tide blooms. However budget calculations indicate that nitrogen supply from groundwater is 1 2 orders of magnitude higher than other external sources for this ecosystem. Data collected in 1995 demonstrated that Brown Tide blooms utilize dissolved organic nitrogen (DON) for growth as evidenced from the large decrease in DON parallel with cell increase. We hypothesize that bloom initiation is regulated by the relative supply of inorganic and organic nitrogen, determined to a large extent by groundwater flow variability. An appropriate first step to test this hypothesis is the demonstration that there are compounds in the DON that can be efficiently utilized by A. anophagefferens giving it a competitive advantage over other endemic species. We will identify the source of DON that is available to A. anophagefferens via field and laboratory studies. The laboratory work will involve the identification of the DON components from the Peconic Estuary that can support growth of the alga and characterization of the DON uptake systems and utilization mechanisms that make this alga competitive at utilizing nitrogen. Immunological probes to major proteins involved in the utilization of DON will be prepared. In the field we will characterize the DON fraction utilized by A. anophagefferens during a bloom as well as follow the nitrogen nutrition of this algae using immunological probes. Weekly nutrient bioassays and analysis of various dissolved and particulate nitrogen pools will complement the more detailed field sampling.