The Indian Sundarbans is a highly vulnerable ecosystem exposed to climate change with salinity intrusion, increasing cyclones as well as anomalies in rainfall and temperature that create an adverse impact on the physiology of resident and migratory fishes. Changes in the density and morphology of chloride cells are essential adaptive characters in response to varying salt level in the environment. Therefore, the present study attempts to compare the morphology, localization and abundance of chloride cells in the fishes representing different migratory guilds of the Matla River estuary of Sundarbans. The variations in the respective expression of the Na${}^{+}$K${}^{+}$ATPase $\alpha$1 protein in chloride cells could comprehend the physiological adjustments across different migratory fish guilds. As observed in the present study, the chloride cells were concentrated at the base of the secondary lamellae in estuarine fishes whereas they occupied the interlamellar position for freshwater, air-breathing and amphidromous fishes, with the variations of such localizations being very prominent. The mean length of chloride cells was significantly higher in estuarine migratory fishes as compared to the amphidromous and freshwater species. However, the abundance of these cells was significantly higher in the estuarine migratory species and freshwater Labeo rohita compared to amphidromous ones. The combined patterns in abundance and immunolocalization of Na${}^{+}$K${}^{+}$ATPase in chloride cells illustrated a unique pattern and functional plasticity in the ion-transporting epithelia of the freshwater and estuarine fishes with important mechanisms of osmoregulatory ability. Hence, the study provides a clue to how osmoregulatory adjustments could be linked to the adaptive strategies in the ichthyofaunal communities of a mangrove estuary as vulnerable as Sundarban. Further studies may facilitate a better understanding of the fish physiology in formulating efficient management efforts to conserve aquatic resources in such vulnerable environments with a view to a certain climate change.

印度孙德尔本斯是一个极易受到气候变化影响的生态系统，盐分侵入、气旋增加以及降雨和温度异常，对居民和洄游鱼类的生理产生不利影响。氯化物细胞密度和形态的变化是响应环境中不同盐度水平的基本适应性特征。因此，本研究试图比较代表 Sundarbans 马特拉河河口不同洄游行会的鱼类中氯化物细胞的形态、定位和丰度。Na 的各自表达的变化${}^{+}$钾${}^{+}$ATP酶 $\alpha$氯细胞中的 1 蛋白质可以理解不同洄游鱼类行会的生理调整。正如在本研究中观察到的，氯细胞集中在河口鱼类的次生层的底部，而它们占据淡水、呼吸空气和两栖鱼类的层间位置，这种定位的变化非常突出。与两栖和淡水物种相比，河口洄游鱼类的氯细胞平均长度显着更高。然而，与两栖动物相比，河口洄游物种和淡水Labeo rohita中这些细胞的丰度显着更高。Na 丰度和免疫定位的组合模式${}^{+}$钾${}^{+}$氯化物细胞中的 ATP 酶在淡水和河口鱼类的离子转运上皮细胞中具有独特的模式和功能可塑性，具有重要的渗透调节能力机制。因此，该研究提供了一条线索，说明渗透压调节如何与像孙德尔班一样脆弱的红树林河口鱼类群落中的鱼群群落的适应性策略联系起来。进一步的研究可能有助于更好地了解鱼类生理学，以制定有效的管理措施，以在这种脆弱的环境中保护水生资源，以应对某种气候变化。