( ( Water temperature ) ( ( can ( ( ( ( speed ( this migration ) ) up ) or ) ( ( ( slow it ) down ) ( by weeks ) ) ) ) . ) )
(ROOT (S (NP (NNP Water) (NN temperature)) (VP (MD can) (VP (VP (VB speed) (NP (DT this) (NN migration)) (PRT (RP up))) (CC or) (VP (VB slow) (NP (PRP it)) (PRT (RP down)) (PP (IN by) (NP (NNS weeks)))))) (. .)))
Water temperature can speed this migration up or slow it down by weeks.
(ROOT (S (PP (IN As) (NP (NP (DT the) (NN temperature)) (PP (IN of) (NP (NN water) (NNS decreases))))) (, ,) (NP (DT the) (NN water) (NNS molecules)) (VP (VB slow) (PRT (RP down))) (. .)))