Profundal

However, if some of the bottom area has fine-grained sediments and is free of all conspicuous plants and algae, this area is often considered the profundal zone.

C. staphylinus is common and abundant in northern Europe and the USA, and is found in permanent shallow ponds, rivers and the littoral zone of lakes. It occurs also in deep alpine lakes, but not in the profundal zone.

The profundal zone consists largely of two feeding guilds, benthivores and carnivores (predators), at least in oligotrophic and mesotrophic lakes.

The ratio of Oligochaeta/Chironomidae was similar to those in profundals of oligotrophic lakes.

The role of chironomids was, in general, important in the profundal of the reservoirs.

Tubifex (Peloscolex) nomurai, which was recorded from profundal bottoms deeper than 400 m in Lake Tazawa, is the only species identified solely from the profundal of oliogotrophic caldera lakes.