What is "aufwuchs"

n. The small animals and plants that encrust hard substrates, such as rocks, in aquatic environments.

Aufwuchs ( German "surface growth" or "overgrowth") is the collection of small animals and plants that adhere to open surfaces in aquatic environments, such as parts of rooted plants. In both marine and freshwater environments, algae – particularly green algae and diatoms – make up the dominant component of aufwuchs communities. Small crustaceans, rotifers, and protozoans are also commonly found in fresh water and the sea, but insect larvae, oligochaetes and tardigrades are peculiar to freshwater aufwuchs faunas.

Many aquatic animals feed extensively on aufwuchs. The mbuna cichlids from Lake Malawi are particularly well known examples of fish adapted for feeding on aufwuchs. Examples include Labeotropheus trewavasae and Pseudotropheus zebra. They have scraper-like teeth that allow them to rasp the aufwuchs from rocks. In marine communities, aufwuchs food sources are important for animals such as limpets and sea urchins.