Climate-change impacts on fish and wildlife habitat in coastal wetlands of Georgian Bay

1998年5月至2000年1月，休伦湖的水位从海拔176.91米下降到175.92米。在接下来的十年里，月平均水位为176.0米，预计到2012年底水位还会进一步下降。全球环流模型预测，五大湖的水位会下降，这是全球气候变化的一种表现。水位下降已经使乔治亚湾(休伦湖东部)的许多沿海湿地干涸，众所周知，这些湿地为鱼类和野生动物物种提供了关键的栖息地。我们的研究表明，在7个湿地中，在10年内(1999-2009年)观测到的80厘米的下降相当于平均25%的水生生境转变为陆地生境。水位的下降还切断了乔治亚湾五分之一的湿地，并阻止了迁徙鱼类季节性进入产卵和育苗栖息地。除了对迁徙鱼类的影响外，湿地栖息地的丧失也可能对半水栖海龟产生负面影响，如布兰德海龟，它们在筑巢迁徙之前将沿海湿地作为取食的中转区。这项提案的主要目标是确定乔治亚湾不同区域鱼类和野生动物栖息地与水位之间的关系，包括低水位与人类发展混为一谈的南部地点、主要不受人类活动干扰的北部地点以及有和没有沿海湿地的岛屿。我将使用无线电发射器来确定北部梭鱼和麝香所使用的产卵和产卵栖息地，并结合启用GPS的无线电遥测和监视摄像头来确定布兰德海龟季节性使用的水生和陆地栖息地。这些信息将被纳入地理信息系统，并辅之以水深和等高线数据，以建立每个物种的栖息地适宜性模型。然后，我将量化整个乔治亚湾代表地点的关键栖息地的数量，作为不同水位情景的函数。第二个目标是了解堤防作为防止湿地干涸的可能缓解措施的影响。

Between May 1998 and January 2000, the water level in Lake Huron dropped a meter from 176.91 m above sea level (asl) to 175.92 m. During the following decade, mean monthly water levels averaged 176.0 m asl, and levels are expected to drop even further by the end of 2012. Such a drop in water levels in the Great Lakes has been predicted by Global Circulation Models as a manifestation of global climate change. The water-level decline has dried up many coastal wetlands in Georgian Bay (eastern arm of Lake Huron), which are known to provide critical habitat for fish and wildlife species. Our research showed that in 7 wetlands, an observed drop of 80 cm over a ten-year period (1999-2009) corresponded to an average of 25% of aquatic habitat being converted to terrestrial habitat. This water-level drop also disconnected a fifth of all wetlands from Georgian Bay, and has prevented seasonal access of migratory fish into spawning and nursery habitat. Besides its impact on migratory fish, loss of wetland habitat may also have a negative effect on semi-aquatic turtles such as the Blanding's turtle, which use coastal wetlands as staging areas to feed prior to their nesting migrations. The primary goal of this proposal is to determine the relationship between fish and wildlife habitat and water level in different regions of Georgian Bay, including a southern site where the low water level is confounded with human development, a northern site that is primarily undisturbed by human activities, and islands with and without coastal wetlands. I will use radio-transmitters to determine the spawning and nursery habitat used by northern pike and muskellunge and a combination of GPS-enabled radio-telemetry and surveillance cameras to determine aquatic and terrestrial habitat used seasonally by the Blanding's turtle. The information will be incorporated into a Geographic Information System and supplemented with bathymetric and contour data to build habitat-suitability models for each species. I will then quantify the amount of critical habitat as a function of different water-level scenarios for representative sites throughout Georgian Bay. A second goal is to understand the impacts of diking as a possible mitigation measure to prevent wetland dessication.