(S (S (PP (IN With) (BASENP (PDT such) (DT an) (JJ abundant) (NN food) (NN source))) (COMMA ,) (S (BASENP (NN algae) (NNS blooms)) (VP (MD can) (VP (VP (VB cover) (NP (BASENP (JJ large) (NNS surfaces)) (PP (IN of) (BASENP (NN water))))) (CC and) (VP (VP (VP (VB choke) (PRT (RP off))) (BASENP (NN sunlight))) (PP (TO to) (BASENP (JJ underwater) (NNS plants)))))))) (PERIOD .))