Vertical variations of dissolved carbohydrates in the North Yap Trench

The concentrations of dissolved monosaccharides (MCHO), polysaccharides (PCHO), and total carbohydrates (TCHO) in the seawater samples collected from the north of the Yap Trench in the western Pacific Ocean were measured by 2,4,6-tripyridine-s-triazine (TPTZ) spectrophotometry method. The results show that the concentrations of MCHO, PCHO, and TCHO ranged from 4.6 to 22.1 μmol C/L, 3.5 to 27.3 μmol C/L, and 13.8 to 36.3 μmol C/L, respectively. In different sampling stations, the concentrations of MCHO, PCHO, and TCHO with water depth showed complex variation patterns. In the study area, the maximum concentrations of MCHO, PCHO, and TCHO occurred in the euphotic layer and the minimum concentrations occurred in mesopelagic seawater layer. Generally, the concentrations of MCHO, PCHO, and TCHO decreased with water depth from the euphotic layer to the hadal zone. The average value of PCHO/TCHO was higher than the average value of MCHO/TCHO, indicating that PCHO was the main component of TCHO in north of the Yap Trench.