( ( The answer ) ( ( is ( ( upwelling -- ) ( ( a movement ) ( of ( ( deep ( , ( nutrient ( rich water ) ) ) ) ( to ( the surface ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN answer)) (VP (VBZ is) (NP (NP (VBG upwelling)) (: --) (NP (NP (DT a) (NN movement)) (PP (IN of) (NP (NP (JJ deep) (, ,) (JJ nutrient) (JJ rich) (NN water)) (PP (TO to) (NP (DT the) (NN surface)))))))) (. .)))
The answer is upwelling -- a movement of deep, nutrient rich water to the surface.
(ROOT (S (NP (NNP Upwelling)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (SBAR (WHADVP (WRB when)) (S (NP (JJ deep) (NN ocean) (NN water)) (VP (VBZ rises) (PP (TO to) (NP (DT the) (NN surface))))))))) (. .)))
Upwelling is the term for when deep ocean water rises to the surface.