Salinity in estuarine environments is one of the most important influencing factors for meiofauna. The effects of seasonal variation in rainfall and saline intrusion on meiofauna/nematodes diversity and abundance on a mesotidal beach located in the mixing zone of an Amazon estuary were analyzed. Samplings occurred bimonthly over one year at four stations in the intertidal zone. Density variation in meiofauna community had a direct relationship with increased rainfall and decreased salinity. Oligochaeta had the highest density during the months with the highest rainfall and lowest salinity. The highest total Nematoda richness value, as well as richness of brackish water genera value, was registered in September and gradually decreased until March, a month with the highest rainfall. Enoplolaimus, a typical predator, had the highest densities in the months with the highest rainfall, probably due to the food availability (Oligochaeta). The highest Nematoda density at the station closest to the high-tide mark occurred due to detritus accumulation. On the other hand, the lower densities at the middle stations are due to the higher desiccation that occurs in these regions compared to the station closer to the low-tide mark. Meiofauna was strongly affected by seasonal changes in rain and salinity, both at the level of large groups and at the level of Nematoda genera. In addition, seasonal changes in salinity clearly affected organisms indirectly through their prey-predator interactions.

河口环境中的盐度是鱼类群落最重要的影响因素之一。分析了降雨和盐分入侵的季节性变化对位于亚马逊河口混合区的中生代海滩上的食肉动物/线虫多样性和丰度的影响。在潮间带的四个站点上，在一年中每两个月进行一次采样。淡水动物群落的密度变化与降雨增加和盐度降低有直接关系。在月份中，Oligochaeta的密度最高，降雨量最高，盐度最低。线虫总富度值最高，以及咸水属的总值最高，发生在9月，并逐渐下降到3月，这是降雨量最高的月份。no草，典型的食肉动物，在降雨量最高的月份中，密度最高，可能是由于食物供应量（Oligochaeta）。由于碎屑堆积，最接近潮汐标记的站点出现了最高的线虫密度。另一方面，与靠近低潮标记的测站相比，中间测站的密度较低是由于在这些区域中发生的干燥程度较高。不论是在大型群体还是在线虫属的水平上，雨和盐度的季节性变化都严重影响了Meiofauna。此外，盐度的季节性变化显然通过其猎物与天敌之间的相互作用间接地影响了生物。