ABSTRACT

Numerous fresh and saline-water tropical aquaculture ponds that often can be significant sources super-saturation of CO₂ towards the atmosphere are gradually increasing throughout the world. The role of salinity in regulating the chlorophyll-a and dissolved pCO₂ in a freshwater aquaculture pond, situated in East Kolkata Wetlands, Eastern India, was tested using a microcosm conducted during summer (April-May) and winter (December–January) months. The effects of enhanced salinity to microcosm sets of 5, 10 and 15 ppt were monitored for nine consecutive days. pH, dissolved oxygen (DO), pCO₂(water), chlorophyll-a, and gross primary productivity (GPP) were measured in-situ and every day during the entire microcosm. Enhanced salinity was hypothesised to alter the pCO₂(water) and chl-a dynamics of this system significantly. Increasing salinity to 5 ppt would enhance the photosynthetic potential of the existing primary producers and reduce the pCO₂(water) significantly, thus boosting the CO₂ sink strength. This enhanced CO₂ sink strength, accompanied with increased GPP and DO, was also observed in 10 ppt, only during summer; however, low temperature was found to abate the photosynthetic response during winter. Finally, in 15 ppt treatments, drastic chlorophyll-a reduction and extreme CO₂ super-saturation showed the existing phytoplankton community cannot cope with such high salinity.

摘要

许多淡水和咸水热带水产养殖池塘通常可能是向大气中超饱和 CO _{2 的}重要来源，它们在世界范围内逐渐增加。使用夏季（4 月至 5 月）和冬季（12 月至 1 月）月份进行的缩影测试盐度在调节位于印度东部加尔各答湿地的淡水养殖池塘中的叶绿素a和溶解 pCO ₂中的作用. 连续 9 天监测提高盐度对 5、10 和 15 ppt 的微观集的影响。pH值，溶解氧（DO），的pCO ₂（水），叶绿素一个，和总初级生产力（GPP）测量原位以及整个微观世界中的每一天。增强的盐度假设的改变的pCO ₂（水）和chl-一个显著该系统的动态特性。将盐度增加到 5 ppt 将提高现有初级生产者的光合作用潜力，并显着减少 pCO ₂（水），从而提高 CO ₂汇强度。这种增强的 CO ₂汇强度，伴随着 GPP 和 DO 的增加，也在 10 ppt 中观察到，仅在夏季；然而，发现低温会减弱冬季的光合作用反应。最后，在 15 ppt 处理中，叶绿素-a 显着减少和 CO ₂ 超饱和表明现有的浮游植物群落无法应对如此高的盐度。