Experimental design of the microfluidic chip. (A) Microscopic image of ciliates from the interstitial region of a sandy beach (Helgoland Island, North Sea, Germany), serving as an ecological reference for distinct environmental patches, analogous to those in our microfluidic chip. (B) The microfluidic chip with all chambers numbered as used later in the presentation of results. (C) Video-view of a microfluidic chip habitat patch, highlighting ciliate cells with squares and their movement trajectories. For further details, see Methods section.