( Then ( there ( ( is ( ( the issue ) ( of ( ( fresh or ) ( salt water ) ) ) ) ) . ) ) )
(ROOT (S (RB Then) (NP (EX there)) (VP (VBZ is) (NP (NP (DT the) (NN issue)) (PP (IN of) (NP (NP (JJ fresh)) (CC or) (NP (NN salt) (NN water)))))) (. .)))
Then there is the issue of fresh or salt water.
(ROOT (S (NP (JJ Fresh) (NN water) (NNS biomes)) (VP (VBP are) (VP (VBN defined) (PP (IN by) (NP (JJ low) (NN salt) (NN concentration))))) (. .)))