Nutrients and Primary Production in the Estuary of the Razdol’naya River (Amur Bay, Sea of Japan)

Abstract

The behavior of the basic nutrients (NO 3 , PO 4 , SiO 2 ) was studied in the estuary of the Razdol'naya River in low and high water, the flow was 4.3 × 10 6 m 3 /day and 10.8 × 10 6 m 3 /day, respectively. It was shown that within the limits of the euphotic zone the nutrients were characterized by a pronounced nonconservative behavior caused by their removal by phytoplankton in primary production. It was determined that phytoplankton removal of nutrients occurred with ratios ∆ C : ∆ NO 3 : ∆ P : ∆ Si = 105 : 18 : 1 : 37 and ∆ C : ∆ NO 3 : ∆ P : ∆ Si = 93 : 11 : 1 : 29 at a respective ratio P : NO 3 : Si = 1 : 22 : 140 in low water and P : NO 3 : Si = 1 : 17 : 120 in high water. It was also determined that the maximum rate of nutrient removal was 4 times higher in the high water than in the low water. The maximum value of primary production of phytoplankton was 2.5-4.0 gC/m 2 day. The estuary area of the Razdol'naya River was specified by rather high production. Such a rate of estuarine primary production, caused by nutrients carried out by the river, being no less than 250 t of dry weight of phytoplankton a day, can provide daily production up to 800 t of biomass in the secondary chain of the ecosystem.

Community structure and spatial distribution of phytoplankton in relation to hydrography in the Laptev Sea and the East Siberian Sea (autumn 2008)

“…The highest chlorophyll a concentrations were found in the upper layers of the fresh water plume northward of the Lena Delta and freshened waters in the southeastern part of the Laptev Sea with high content of dissolved silicate. These findings are in agreement with the well-known fact that river plume supports higher production than surrounding shelf waters (Smetacek 1986;Zvalinsky et al 2005). The values of chlorophyll a estimated in our study are comparable to those reported for offshore zone of the Barents Sea (0.14-6 mg/m 3 ; Makarevich and Druzhkova 2010) and the freshened waters of the northwestern Kara Sea in early autumn (0.85-1.41 mg/m 3 ; Sukhanova et al 2012) as well as for the southeastern Laptev Sea at the beginning of the freeze-up (0.1-3.2 mg/m 3 ; Tuschling et al 2000).…”

Fluxes and retention of nutrients and organic carbon in Manko estuary, Okinawa, Japan: influence of river discharge variations

“…Although quantifying material fluxes from rivers to coastal regions is notoriously difficult [9], there is increasing interest in quantifying material fluxes into estuaries on global [16], regional [17], and local scales [5]. Knowledge of fluxes has been successfully used to study biogeochemical processes in estuaries and, particularly, to estimate primary production [18].…”