To investigate the effects of river waters on estuarine seagrass, the tropical seagrass Halophila ovalis was collected at Brunei Bay, Borneo, and was cultured under laboratory conditions for 18 days. Three treatments were set up in the experiment: natural seawater with a salinity 30 (S30), estuarine river water with a salinity 10 (S10), and the intermediate water that was composed of the seawater and river water with a salinity 20 (S20). New leaf production, the average length of new leaves, rhizome elongation, and photosynthetic rate of H. ovalis were significantly higher in S20 than S10. Chlorophyll a (chl a ) and carotenoid content in H. ovalis were significantly lower in S10 than S20 and S30. Though the tropical river waters could potentially cause both positive and negative effects on seagrass, the present results suggested that low salinity would be the most influential factor to hinder the growth and metabolism of H. ovalis, and the salinity threshold was observed between 10 and 20. These results suggested that H. ovalis may be able to extend its present distribution to the upper estuary at this study site in the future.

中文翻译：

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河流入水对热带海草椭圆形嗜盐菌生长，光合作用和呼吸作用的影响

为了研究河水对河口海草的影响，在婆罗洲文莱湾收集了热带海草椭圆形嗜盐菌，并在实验室条件下培养了18天。实验中设置了三种处理方法：盐度为30的天然海水（S30），盐度为10的河口河水（S10）和由海水和盐度为20的河水组成的中间水（S20） 。在S20中，新叶的产生，新叶的平均长度，根茎伸长和卵形H.的光合速率均显着高于S10。在S10中，卵形嗜血杆菌中的叶绿素a（chl a）和类胡萝卜素含量显着低于S20和S30。尽管热带河水可能对海草造成正反两面的影响，