SGER: Examining the Effects of Hurricane Ivan in Coastal Alabama and Northwestern Florida: A Positive Impact on Shallow Coastal Lagoons?

沿海泻湖是陆地-海洋边缘生态系统的关键组成部分，因为它们无处不在，而且发挥着重要的生态作用，例如为许多生物提供食物和庇护所，过滤来自陆地的营养物质，防止海岸线受到侵蚀。2004年9月16日，三级飓风伊万在彭萨科拉湾附近的佛罗里达半岛西北部登陆。这场风暴造成了重大破坏，包括人员伤亡和房屋、道路、水电设施的大量破坏。在过去的四年里，PI一直在广泛研究位于受飓风影响最严重的地区的三个沿海泻湖的生态。 因此，飓风通过太平洋岛屿研究中心的研究地点，结合飓风前为这些地点编制的广泛数据集，建立了一个前所未有的自然实验，以研究飓风对这些重要沿海环境生态的影响。事实上，与飓风对珊瑚礁、河口和沼泽或红树林群落影响的现有研究相比，人们对飓风如何影响沿海泻湖及其对生态系统的重要作用知之甚少，对沿海泻湖的关注并不是这项建议的唯一新颖之处。参与者还预计，伊万飓风将对沿海泻湖的生态特性产生相当积极的影响，这将抵消据报对河口、珊瑚礁和沼泽/红树林社区往往产生的负面影响。以下两个论点被援引来预期对沿海泻湖的积极影响。 首先，沿海泻湖，鉴于其错综复杂和受保护的形态，往往有一个有限的fetch（即开放水域，通过风可以建立剪切底部）。因此，飓风对泻湖的底栖植物（海草和大型藻类）施加的剪切强度将受到泻湖形态的固有限制，并且很可能通过修剪旧的部分和组织并使植物恢复活力而产生积极影响。第二，由于没有河流输入（例如，在河口发生的情况）和存在相当有限的沿海沃茨开口，沿海泻湖通常具有低至中等的冲刷率。因此，随着风暴驱动的洪水退去，从周围土地输入沿海泻湖的营养物质将留在泻湖中足够长的时间，以供底栖植被有效吸收。沿海泻湖中的底栖植物的生长往往受到养分供应的限制，因此，养分负荷增加加上大量的吸收机会将是伊万飓风对这些植物的另一个积极影响。由于底栖植物是沿海泻湖的主要生产者，也是这些环境生态的关键参与者，我们假设飓风伊万通过刺激底栖植物的生长和健康，也将促进沿海泻湖的生态属性。特别是，PI假设，在飓风伊万通过后，所研究的沿海泻湖将增加初级生产，为生物体提供更高和更好的庇护所（因此在底栖草甸中有更高水平的大型动物），过滤和储存更大量的土地-在过去的四年里，三个泻湖研究获得的广泛的基线数据允许PI通过简单地比较飓风前基线与飓风后获得的相应测量值。 该研究将为两名研究生提供培训机会。 密西西比-亚拉巴马海洋赠款财团和美国环保署成立的亚拉巴马河口研究中心也支持这一项目。

Coastal lagoons are key components of land-ocean fringe ecosystems in view of their ubiquity and the important ecological roles they play, such as the provision of food and shelter for many organisms, the filtration of land-derived nutrients and the prevention of shoreline erosion. On September 16th 2004, Hurricane Ivan, a category 3 storm, landed on the NorthWestern Floridian Peninsula around Pensacola Bay. The storm generated substantial damage, including the loss of human lives and much destruction of houses, roads and water and electrical facilities. Over the past four years, the PIs have been studying extensively the ecology of three coastal lagoons located in the area most affected by the Hurricane. Hence, the passage of the Hurricane through the PIs study sites, in conjunction with the pre-hurricane extensive date set compiled for the sites, sets up an unprecedented natural experiment to examine the impacts of hurricanes on the ecology of these important coastal environments. Indeed, little is known as to how hurricanes may affect coastal lagoons and the important services they offer to the ecosystem, in contrast with the several existing studies of hurricane impacts on coral reefs, estuaries and marsh or mangrove communities.The focus on coastal lagoons is not the only novel aspect of this proposal. The PIs also expect that Hurricane Ivan will have a rather positive effect on the ecological attributes of coastal lagoons, which would counter the often negative effects that have been reported for estuaries, coral reefs and marsh/mangrove communities. The two arguments invoked to expect positive effects on coastal lagoons are as follows. First, coastal lagoons, in view of their convoluted and protected morphology, frequently have a restricted fetch (i.e. area of open water through which the wind can build up shear on the bottom). Hence, the intensity of shear imposed by the Hurricane on the benthic plants (seagrasses and macroalgae) of a lagoon would be inherently limited by the lagoon morphology and, likely, rather entail a positive effect by pruning old parts and tissues and rejuvenating the plants. Second, coastal lagoons have generally low to moderate flushing rates due to the absence of riverine inputs (as it happens, for instance, in estuaries) and the presence of a rather constrained opening into coastal waters. Thus, the nutrients imported into coastal lagoons from surrounding land as storm-driven flooding recedes would remain in the lagoons long enough for efficient uptake by benthic vegetation. The growth of benthic plants in coastal lagoons is often limited by nutrient availability and, thus, increased nutrient loading in combination with ample opportunity for uptake would represent another positive effect of Hurricane Ivan on those plants. Since benthic plants are the dominant producers in coastal lagoons and key players in the ecology of those environments, we hypothesize that Hurricane Ivan, through stimulating the growth and health of benthic plants, will also promote the ecological attributes of coastal lagoons. In particular the PIs hypothesize that, after the passage of Hurricane Ivan, the coastal lagoons studied will have increased primary production, offer higher and enhanced levels of shelter to organisms (and thus have higher levels of macrofauna in the benthic meadows) and filter and store larger quantities of land-derived nutrients.The extensive baseline of data obtained for the three lagoons studied over the past four years allows the PIs to unequivocally test their hypotheses by simply comparing the pre-hurricane baseline with corresponding measurements obtained after the Hurricane. The research will provide training opportunities for two graduate students. The Mississippi-Alabama Sea Grant Consortium and the EPA-founded Alabama Center for Estuarine Studies are also supporting this project.