This study evaluated the sedimentation rates of nutrients and particulate matter in Nile tilapia (Oreochromis niloticus) net cage farming in the Umari, Brazilian semi-arid reservoir. Sedimentation chambers were installed under net cages which had stocking of 125 and 100 fish m⁻³ (experimental sites). The natural sedimentation rate of the reservoir (control site) was calculated using a sedimentation chamber installed three meters deep and about 200 m upstream from the net cages. Samples from all chambers were taken after 24 h of installation, at each sampling site. The average sedimentation rates for particulate matter, ammonia, total nitrogen, total phosphorus, total organic carbon, nitrite, nitrate and total inorganic carbon in both experimental and control sites were 8.31, 6.61, and 0.083 mg cm–² day^–1; 60.82, 46.18, and 9.45 μg cm–² day^–1; 0.14, 0.11, and 0.04 mg cm–² day^–1; 189.42, 186.59, and 7.72 μg cm–² day^–1; 1.99, 1.58, and 0.57 mg cm–² day^–1; 0.35, 0.24 and 0.04 μg cm–² day^–1; 6.84, 7.11 and 5.04 μg cm–² day^–1; and 0.18, 0.18 and 0.18 mg cm–² day^–1 respectively. The sedimentation rates in the experimental sites were significantly higher than those in the control site. The fish farming activity in net cages elevates the sedimentation rates of nutrients and particulate matter in this reservoir and could accelerate the eutrophication process, thereby hindering the fish farming activity itself.

这项研究评估了巴西半干旱水库乌马里的尼罗罗非鱼（Oreochromis niloticus）网箱养殖中养分和颗粒物的沉降速率。沉积室安装在网箱下方，网箱的放养量为125和100鱼米^-³（实验地点）。使用安装在网箱上游约三米深，约200 m处的沉淀室计算储层（控制点）的自然沉淀率。安装24小时后，在每个采样点从所有腔室中采样。在实验点和控制点，颗粒物，氨，总氮，总磷，总有机碳，亚硝酸盐，硝酸盐和总无机碳的平均沉降速率分别为8.31、6.61和0.083 mgcm²·day ^–1；60.82、46.18和9.45μgcm–²天^–1；0.14、0.11和0.04 mg cm？²天^–1；189.42、186.59和7.72μgcm–²天^–1；每天1.99、1.58和0.57 mgcm²²– ¹; 0.35、0.24和0.04μgcm–²天^–1；6.84、7.11和5.04μgcm–²天^–1；和分别为0.18、0.18和0.18 mgcm²-day ^–1。实验部位的沉降速率明显高于对照部位。网箱中的养鱼活动提高了该水库中养分和颗粒物的沉降速率，并可能加速富营养化过程，从而阻碍了养鱼活动本身。