Episodic Nutrient Supply to Pelagic Sargassum in Neritic Versus Oceanic Waters

当大型藻类漂流到浅海水域时，远洋马尾藻的生产力可能不会受到营养限制。初步观察表明，相关鱼群产生的间歇性富集可能占浅海水域马尾藻营养物质可获得性的很大一部分。这项工作将：1)量化鱼群的丰度及其作为马尾藻在浅海水域和海洋水域的营养来源的相对重要性。2)描述与鱼群溶解排泄和排泄有关的有机营养库的特征。3)研究马尾藻对氮、磷的短期生理生化响应，这与鱼类排泄物和排泄物有关。这些研究将首次确定鱼类排泄物对大型藻类群落营养供应的潜在重要性。通常情况下，近海水域的植物生长主要是悬浮在表面日光层中的微小植物。然而，一种名为马尾藻的漂浮海藻在美国东南海岸附近地区很常见。在这项拟议的工作中，拉波因特试图回答有关这种不同寻常的浮游生物形式的大规模(盆地)分布的问题。他将检验这一假说，即马尾藻在近岸水域的循环是一个关键阶段，在此期间，鱼群中的营养物质缓解了植物在更多近海水域遇到的营养耗尽状况。这是一种独特的“生态生理学”方法，将大型藻类生物学的研究与大规模海洋条件的研究相结合。Lapointe博士是公认的海藻营养专家，这项工作将有助于阐明大西洋亚热带地区的植物生产生态。

The productivity of pelagic Sargassum may not be nutrient limited at those times when the macroalga drifts into neritic waters. Preliminary observations suggest that episodic enrichment resulting from associated fish schools may account for a large fraction of nutrient availability to Sargassum in neritic waters. This work will: 1) Quantify the abundance of fish schools and their relative importance as a nutrient source to Sargassum in neritic versus oceanic waters. 2) Characterize the organic nutrient pools associated with dissolved excretion and defecation by fish schools. 3) Characterize short term physiological and biochemical responses of Sargassum to N and P enrichment typical of that resulting from fish excretion and defecation. These studies will determine for the first time the potential importance of fish excretion to nutrient supply of a macroalgal community. Typically, plant growth in offshore waters is dominated by microscopic plants suspended in the surface sunlit layer. However, a floating seaweed called Sargassum is common throughout the area off the southeast coast of the United States. In the proposed work, Lapointe seeks to answer questions regarding the large scale (basin) distribution of this unusual plankton form. He will examine the hypothesis that the circulation of Sargassum through nearshore water is a critical stage during which nutrients from schooling fish relieve the nutrient depleted conditions that the plants encounter in more offshore waters. This is a unique "ecophysiological" approach that blends research in the biology of macroalgae with research in large scale oceanographic conditions. Dr. Lapointe is a recognized expert in the nutrition of seaweeds and this work will help clarify the plant production ecology of Atlantic subtropical regions.