(S (S (ADVP (RB Later)) (S (SBAR (WHADVP (WRB when)) (S (BASENP (DT the) (NNS plants)) (VP (VBP die)))) (COMMA ,) (S (NP (BASENP (DT the) (NN process)) (PP (IN of) (NP (BASENP (PRPD their) (NN decomposition)) (PP (IN on) (BASENP (DT the) (NN bottom)))))) (VP (VP (VBZ consumes) (BASENP (NN oxygen))) (PP (TO to) (NP (BASENP (DT a) (NN state)) (SBAR (WHADVP (WRB where)) (S (BASENP (DT the) (NN water)) (VP (VBZ becomes) (ADJP (ADJP (JJ anoxic)) (CONJP (COMMA ,) (CC and)) (ADJP (JJ unable) (S (VP (TO to) (VP (VB support) (BASENP (NN life)))))))))))))))) (PERIOD .))