What are biotic factors in the lake ecosystem?

bi·ot·ic
bīˈädik
adjective
relating to or resulting from living things, especially in their ecological relations.
"the preservation of biotic diversity"
~google.com

en.wikipedia.org/wiki/Ecosystem
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. It refers to both biotic factors as well as abiotic factors.
~wikipedia

Things that live in a lake might include fish, aquatic plants, algae, worms, and various kinds of insects. Birds sometimes catch fish, and sometimes leave droppings. Large animals often stir the mud and leave what ever was on their fur when they entered the water. Small animals such as beavers might add leaves and tree chips to the water. Snakes and other small animals might fall into the water and drown.