Comparison of Lake Biwa and Great Lakes on the Functions of Littoral Zone

对休伦湖萨吉诺湾湿地的水位、水流、温度、电导率和浊度的水平分布进行了测量。在夏季，垂直于海岸线的样带上存在显著的水质梯度。近岸水域水质干净，电导率高，而近岸部分水域水质浑浊，电导率低。大幅度的水位变化在湿地中经常发生。一个这样的变化周期约为24小时，另一个周期约为3小时。前者是由每天从陆地和海湾吹来的风的方向变化引起的。后者是由海湾的横向表面淤积造成的。水位变化对湿地水质空间分布的影响；即随着水位的上升和下降，清澈的近岸水和管状的近海水之间的锋面分别向内和向外移动。水流垂直于海岸，通常非常微弱（2-3厘米/秒）。在萨吉诺湾的海岸地带，以美洲芦苇（Scripus americanus）为主的新兴湿地是常见的。在湿地近岸部分，美洲山菖蒲芽上浮游植物群落的叶绿素a浓度显著高于近岸部分的每枝和单位表面面积。每根和单位面积附生叶绿素a的总初级生产力在离海岸越远的地方最高。在夏季，浓密的芦苇枝阻碍了湿地近岸和近海部分之间的水混合。近岸水域存在与死亡植被分解相关的缺氧条件，特别是在清晨。与湿地的近海部分相比，近岸水域的硫酸盐浓度较低。这种差异是由于近岸缺氧条件下硫酸盐的减少造成的。与湿地的近海部分相比，近岸水域也含有高浓度的Mg++、Na+、cl-和其他离子。浅层近岸水的蒸发和蒸腾损失，以及缺少近岸水与海湾水的混合，这可能是造成这些差异的原因，这种情况在湿地的近海部分发生过。少

The horizontal distribution of water level, current, temperature, electric conductivity and turbidity were measured in wetland in Lake Huron's Saginaw bay.During summer, remarkable gradients of water quality existed on transect perpendicular to the coast line. Nearshore water was clean with high conductivity, while water in offshore portions of the wetland was turbid and had low conductivity. Large amplitude water level changes occurred commonly in the wetland. The cycle of one such change had a period of approximately 24 hrs, and another a period of about 3 hrs.The former were caused by daily changes in the direction of breezes blowing from the land and from the bay. The latter resulted from transverse surface seiche in the bay.Water level changes influenced spatial distribution of water quality in the wetland ; that is, the front between clear nearshore water and tubed offshore water moved inward and outward from shore as water level rose and fell respectively.Currents associated wit … More h rise and fall of water level ran perpendicular to shore and were generally very weak (2-3 cm/sec).Emergent wetlands dominated by the bulrush Scripus americanus are common in the shore zone of Saginaw Bay. Chlorophyll a concentration from algae in the periphyton community on shoots of Scirpus americanus were significantly higher per shoot and per unit area of shoot surface in offshore portions of the wetland than in nearshore portions. Gross primary productivity of periphytic algae per shoot and per unit area of epiphytic chlorophyll a was highest further from the shore.During summer, dense bulrush shoot impede mixing of water between nearshore and offshore portions of the wetland. Anoxic conditions associated with decomposition of dead vegetation existed in nearshore water, particularly in early morning.Low sulfate concentrations were present in nearshore water as compared to water in offshore portion of the wetland. This difference was caused by reduction of sulfate under anoxic nearshore conditions. Nearshore water also had high concentrations of Mg++, Na+, and cl- and other ions as compared to water in offshore portions of the wetland. Evaporation and transpiration losses from shallow nearshore water, and absence of mixing of nearshore water with water from the bay as occurred in offshore portions of wetland, may have caused these differences. Less