toxic chemicals are dumped into a pond & toxic chemicals are poisonous ->  the pond is poisonous because of toxic chemicals  poisonous things can cause harm to organisms & harming an organism can cause that organism to die ->  poisonous things can cause organisms to die  a pond is a kind of body of water & a fish lives in water ->  fish live in ponds  fish live in ponds & a fish is a kind of organism ->  a fish is a kind of organism that lives in ponds  the pond is poisonous because of toxic chemicals & poisonous things can cause organisms to die & a fish is a kind of organism that lives in ponds -> the pond with toxic chemicals can cause fish in the pond to die