Powell Eric N, Klinck John M, Hofmann Eileen E, McManus Margaret A
Haskin Shellfish Research Laboratory, Rutgers University, 6959 Miller Ave., Port Norris, New Jersey 08349, USA.
Environ Manage. 2003 Jan;31(1):100-21. doi: 10.1007/s00267-002-2695-6.
A hydrodynamic-oyster population model was developed to assess the effect of changes in freshwater inflow on oyster populations in Galveston Bay, Texas, USA. The population model includes the effects of environmental conditions, predators, and the oyster parasite, Perkinsus marinus, on oyster populations. The hydrodynamic model includes the effects of wind stress, river runoff, tides, and oceanic exchange on the circulation of the bay. Simulations were run for low, mean, and high freshwater inflow conditions under the present (1993) hydrology and predicted hydrologies for 2024 and 2049 that include both changes in total freshwater inflow and diversions of freshwater from one primary drainage basin to another. Freshwater diversion to supply the Houston metropolitan area is predicted to negatively impact oyster production in Galveston Bay. Fecundity and larval survivorship both decline. Mortality from Perkinsus marinus increases, but to a lesser extent. A larger negative impact in 2049 relative to 2024 originates from the larger drop in fecundity under that hydrology. Changes in recruitment and mortality, resulting in lowered oyster abundance, occur because the bay volume available for mixing freshwater input from the San Jacinto and Buffalo Bayou drainage basins that drain metropolitan Houston is small in comparison to the volume of Trinity Bay that presently receives the bulk of the bay's freshwater inflow. A smaller volume for mixing results in salinities that decline more rapidly and to a greater extent under conditions of high freshwater discharge.Thus, the decline in oyster abundance results from a disequilibrium between geography and salinity brought about by freshwater diversion. Although the bay hydrology shifts, available hard substrate does not. The simulations stress the fact that it is not just the well-appreciated reduction in freshwater inflow that can result in decreased oyster production. Changing the location of freshwater inflow can also significantly impact the bay environment, even if the total amount of freshwater inflow does not change.
开发了一种水动力-牡蛎种群模型，以评估淡水流入变化对美国得克萨斯州加尔维斯顿湾牡蛎种群的影响。该种群模型包括环境条件、捕食者和牡蛎寄生虫——马氏帕金虫对牡蛎种群的影响。水动力模型包括风应力、河流径流、潮汐和海洋交换对海湾环流的影响。在当前（1993年）水文条件以及预测的2024年和2049年水文条件下，针对低、中、高淡水流入情况进行了模拟，其中包括总淡水流入量的变化以及淡水从一个主要排水流域转移到另一个流域的情况。预计为供应休斯敦大都市区而进行的淡水转移将对加尔维斯顿湾的牡蛎产量产生负面影响。繁殖力和幼虫存活率均下降。马氏帕金虫导致的死亡率增加，但幅度较小。相对于2024年，2049年更大的负面影响源于该水文条件下繁殖力的更大幅度下降。由于与目前接收海湾大部分淡水流入的特里尼蒂湾相比，用于混合来自休斯敦大都市区的圣哈辛托河和布法罗河排水流域的淡水输入的海湾体积较小，导致补充量和死亡率发生变化，从而使牡蛎丰度降低。较小的混合体积导致在高淡水排放条件下盐度下降更快、幅度更大。因此，牡蛎丰度的下降是由淡水转移导致的地理和盐度失衡造成的。尽管海湾水文发生变化，但可用的硬质基质并未改变。模拟结果强调了这样一个事实，即不仅淡水流入量的明显减少会导致牡蛎产量下降。即使淡水流入总量不变，改变淡水流入的位置也会对海湾环境产生重大影响。
