What part of a pond ecosystem is

Question

not a part of the pond community.Explain

First read the definition of community at the following site:
http://en.wikipedia.org/wiki/Community

please read this definition of abiotic

http://en.wikipedia.org/wiki/Abiotic

Then read this definition of ecosystem:
http://en.wikipedia.org/wiki/Ecosystem

So to answer your question, think about an abiotic component of the pond ecosystem.