U.S. Geological Survey, Georgia Cooperative Fish and Wildlife Research Unit, Warnell School of Forestry and Natural Resources, Athens, GA 30602, USA.
Environ Manage. 2011 Jul;48(1):109-22. doi: 10.1007/s00267-011-9688-2. Epub 2011 May 12.
The southeastern United States has experienced severe, recurrent drought, rapid human population growth, and increasing agricultural irrigation during recent decades, resulting in greater demand for the water resources. During the same time period, freshwater mussels (Unioniformes) in the region have experienced substantial population declines. Consequently, there is growing interest in determining how mussel population declines are related to activities associated with water resource development. Determining the causes of mussel population declines requires, in part, an understanding of the factors influencing mussel population dynamics. We developed Pradel reverse-time, tag-recapture models to estimate survival, recruitment, and population growth rates for three federally endangered mussel species in the Apalachicola-Chattahoochee-Flint River Basin, Georgia. The models were parameterized using mussel tag-recapture data collected over five consecutive years from Sawhatchee Creek, located in southwestern Georgia. Model estimates indicated that mussel survival was strongly and negatively related to high flows during the summer, whereas recruitment was strongly and positively related to flows during the spring and summer. Using these models, we simulated mussel population dynamics under historic (1940-1969) and current (1980-2008) flow regimes and under increasing levels of water use to evaluate the relative effectiveness of alternative minimum flow regulations. The simulations indicated that the probability of simulated mussel population extinction was at least 8 times greater under current hydrologic regimes. In addition, simulations of mussel extinction under varying levels of water use indicated that the relative risk of extinction increased with increased water use across a range of minimum flow regulations. The simulation results also indicated that our estimates of the effects of water use on mussel extinction were influenced by the assumptions about the dynamics of the system, highlighting the need for further study of mussel population dynamics.
美国东南部在最近几十年经历了严重且反复发生的干旱、人口的快速增长以及农业灌溉的增加，导致对水资源的需求更大。在同一时期，该地区的淡水贻贝类（Unioniformes）的种群数量大幅下降。因此，人们越来越关注确定贻贝类种群下降与与水资源开发相关的活动之间的关系。确定贻贝类种群下降的原因部分需要了解影响贻贝类种群动态的因素。我们为佐治亚州的阿巴拉契科拉-查塔胡奇-弗林特河流域的三种受联邦保护的贻贝类开发了 Pradel 倒时标记再捕获模型，以估计其生存率、繁殖率和种群增长率。这些模型使用在佐治亚州西南部的萨沃特奇溪连续五年收集的贻贝标记再捕获数据进行参数化。模型估计表明，贻贝的存活率与夏季高流量呈强烈负相关，而繁殖率与春季和夏季的流量呈强烈正相关。使用这些模型，我们根据历史（1940-1969 年）和当前（1980-2008 年）的水流模式以及在不同水平用水条件下模拟了贻贝种群动态，以评估替代最小流量法规的相对效果。模拟结果表明，在当前水文条件下，模拟贻贝种群灭绝的概率至少是历史条件下的 8 倍。此外，在不同用水水平下模拟贻贝灭绝的结果表明，随着最小流量法规范围内用水量的增加，灭绝的相对风险增加。模拟结果还表明，我们对用水对贻贝灭绝的影响的估计受到系统动态假设的影响，突出了进一步研究贻贝种群动态的必要性。
