Although detritivorous Tubificinae and chironomid larvae are important groups in functioning of both, fresh and brackish water ecosystem, their co-occurrence patterns in sediment is weakly known. We carried out two-year-long research in the brackish Vistula Lagoon (southern Baltic Sea), where both Tubificinae (Limnodrilus hoffmeisteri and Potamothrix hammoniensis) and larvae of Chironomus balatonicus occur in high densities. Because of different source of their food, we hypothesized that the ecological interactions between those two groups of detritivores are not antagonistic, thus allowing for their co-occurrence along the depth of sediment profile with lack of competition for space. Here we show that maximum burrowing depth, occasionally reaching 25 cm was significantly affected by the total density of the each group in the entire core. Tubificinae and C. balatonicus showed the highest density at 0–10 cm depth, where they co-occurred most frequently, with significant co-occurrence in the layers of 0–2 cm and 2–5 cm. We propose a hypothetical model of interactions between apparently the same functional groups and the complementary role they play in sediment reworking. It points to their coexistence in the shared microhabitat, but using space and food resources differently. Also, the consequences of their activity and habitat structuring are opposite—Chironomus larvae mostly affect the deeper layers of the sediments, while Oligochaeta both the deeper and surface layers. Thus, their requirements and ecological roles seem not to overlap, preventing competitive exclusion and allowing for co-occurrence.

尽管在淡水和微咸水生态系统中，有害的杜鹃花科和chi虫幼虫是重要的群体，但它们在沉积物中的共生模式却鲜为人知。我们在咸淡的维斯杜拉泻湖（波罗的海南部）进行了为期两年的研究，那里的Tubificinae（Limnodrilus hoffmeisteri和Potamothrix hammoniensis）和Chironomus balatonicus的幼虫都在这里发生在高密度。由于它们的食物来源不同，我们假设这两组有害生物之间的生态相互作用不是拮抗性的，因此允许它们沿着沉积物剖面的深度共存，而缺乏空间竞争。在这里，我们显示最大挖洞深度（偶尔达到25厘米）受整个岩心中每个组的总密度的显着影响。Tubificinae和C. balatonicus在0–10 cm深度处显示出最高的密度，它们最常同时出现，在0–2 cm和2–5 cm的层中同时出现。我们提出了一个假想的模型，这些模型显然是相同的官能团之间的相互作用，以及它们在沉积物返工中所起的互补作用。它指出了它们在共同的微生境中的共存，但是对空间和粮食资源的利用却有所不同。同样，它们的活动和栖息地结构的后果是相反的-Chironomus幼虫主要影响沉积物的深层，而Oligochaeta则影响深层和表层。因此，它们的要求和生态作用似乎并不重叠，从而防止竞争排斥并允许同时存在。