Microscopic sessile suspension feeders live attached to surfaces and, by consuming bacteria-sized prey and by being consumed, they form an important part of aquatic ecosystems. Their environmental impact is mediated by their feeding rate, which depends on a self-generated feeding current. The feeding rate has been hypothesized to be limited by recirculating eddies that cause the organisms to feed from water that is depleted of food particles. However, those results considered organisms in still water, while ambient flow is often present in their natural habitats. We show, using a point-force model, that even very slow ambient flow, with speed several orders of magnitude less than that of the self-generated feeding current, is sufficient to disrupt the eddies around perpendicular suspension feeders, providing a constant supply of food-rich water. However, the feeding rate decreases in external flow at a range of non-perpendicular orientations due to the formation of recirculation structures not seen in still water. We quantify the feeding flow and observe such recirculation experimentally for the suspension feeder Vorticella convallaria in external flows typical of streams and rivers.

微观无柄悬浮喂食器附着在表面上，通过消耗细菌大小的猎物并被消耗，它们形成了水生生态系统的重要组成部分。它们对环境的影响是由它们的进给率调节的，这取决于自生的进给电流。已经假设进食速率受到循环涡流的限制，循环涡流导致生物体从耗尽食物颗粒的水中进食。然而，这些结果考虑了静水中的生物，而环境流通常存在于它们的自然栖息地中。我们使用点力模型表明，即使是非常缓慢的环境流动，其速度比自生馈电电流小几个数量级，也足以破坏垂直悬浮馈线周围的涡流，提供恒定的富含食物的水。然而，由于形成在静水中看不到的再循环结构，在非垂直方向的范围内，外部流动的进料速率会降低。我们量化进料流量并通过实验观察悬浮进料器的这种再循环溪流和河流典型的外部流动中的涡旋菌。