_:b1218169 "PLB:plb"^^ . _:b1218169 . _:b1218169 . _:b1218169 "An expanse of marine water characterised by low concentrations of nutrients such as phosphate, nitrate as well as organic matter and, hence, low primary productivity. These regions tend to have high dissolved oxygen levels due to a lack of respiration."^^ . _:b1218169 .