part of composed primarily of ocean sea oligotrophic water marine oligotrophic desert A marine water mass which is composed primarily of water with low concentrations of nutrients. 2010-03-16T12:16:11Z ORCID:0000-0002-4366-3088 On Earth, the nutrients which are of low concentration in these water masses are typically phosphate, nitrate. and organic matter. The result is low primary productivity in such regions. These regions tend to have high dissolved oxygen levels due to a lack of respiration. marine water mass