In order to understand the ecological functioning of lake ecosystems, little is more crucial than knowledge of their mixing regime. However in tropical regions, this information is scarce for all except the largest lakes, and often inferred from occasional observation of physical water-column properties. In this study, a total of 276 water-column profiles of temperature, conductivity and dissolved oxygen collected between 2000 and 2017 in 60 volcanic crater lakes in equatorial western Uganda are used to classify these lakes according to mixing regime. Most study lakes are small (on average 29 ha), but together they cover a spectacularly large gradient in maximum depth (Z_max) between 1.4 m and > 220 m, and consequently they display a wide range of mixing regimes. We identified four lakes as continuous warm polymictic, 12 as discontinuous warm polymictic, and 11 other lakes mix completely once or twice each year. We classify these 11 lakes as equatorial dimictic, because they experience deep mixing during both dry seasons separated by long periods of stable stratification, while the season of complete mixing may differ between years and among neighbouring lakes. The 33 remaining lakes do not usually mix completely and are thus meromictic. Relative depth (Z_r) is the main factor controlling the mixing regime of these lakes. The presence of a shallow permanent chemocline reduces mixing depth, and the smallest meromictic lakes (< 3 ha) tend to occasionally mix deeper than predicted by Z_r. Based on these variables, predictions can be made about the mixing dynamics of Ugandan crater lakes not covered by our dataset. Previous suggestions that the mixing depth of tropical crater lakes is strongly influenced by the wind shelter provided by a high crater rim or by water-column transparency could not be confirmed.

为了了解湖泊生态系统的生态功能，没有什么比了解它们的混合状态更重要的了。然而，在热带地区，除了最大的湖泊外，其他所有地区都缺乏这种信息，并且通常通过偶尔观察物理水柱特性来推断。在这项研究中，在 2000 年至 2017 年间在赤道乌干达西部的 60 个火山口湖泊中收集的总共 276 个温度、电导率和溶解氧的水柱剖面用于根据混合状况对这些湖泊进行分类。大多数研究湖泊都很小（平均 29 公顷），但它们一起覆盖了最大深度（Z _max) 介于 1.4 m 和 > 220 m 之间，因此它们显示出广泛的混合状态。我们将 4 个湖泊确定为连续暖聚合体，12 个为不连续暖聚合体，其他 11 个湖泊每年完全混合一两次。我们将这 11 个湖泊归类为赤道双混叠层，因为它们在两个旱季都经历了深度混合，而这两个旱季被长期稳定的分层隔开，而完全混合的季节可能因年份和相邻湖泊而异。剩下的 33 个湖泊通常不会完全混合，因此是等离子的。相对深度（Z _r) 是控制这些湖泊混合状态的主要因素。浅层永久趋化层的存在降低了混合深度，最小的分生湖（< 3 公顷）往往混合得比 Z _r预测的更深。基于这些变量，可以对我们的数据集未涵盖的乌干达火山口湖的混合动力学进行预测。之前关于热带火山口湖的混合深度受高火山口边缘提供的避风处或水柱透明度的强烈影响的建议无法得到证实。