( Phytoplankton ( ( are ( ( ( ( the ( main ( food source ) ) ) ( to zooplankton ) ) and ) ( as ( such ( are ( ( an ( important level ) ) ( of ( the ( plankton chain ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Phytoplankton)) (VP (VBP are) (UCP (NP (NP (DT the) (JJ main) (NN food) (NN source)) (PP (TO to) (NP (NN zooplankton)))) (CC and) (SBAR (IN as) (S (NP (JJ such)) (VP (VBP are) (NP (NP (DT an) (JJ important) (NN level)) (PP (IN of) (NP (DT the) (NN plankton) (NN chain))))))))) (. .)))
Phytoplankton are the main food source to zooplankton and as such are an important level of the plankton chain.
(ROOT (S (NP (NNP Phytoplankton)) (VP (VBP make) (NP (NP (NN food)) (PP (IN via) (NP (NN photosynthesis))))) (. .)))