Annual New Production of Phytoplankton Estimated from MODIS-Derived Nitrate Concentration in the East/Japan Sea

Huitae Joo,Seung Son,Dabin Lee,Sang Lee

doi:10.3390/rs10050806

Abstract

Our main objective in this study was to determine the inter-annual variation of the annual new production in the East/Japan Sea (EJS), which was estimated from MODIS-aqua satellite-derived sea surface nitrate (SSN). The new production was extracted from northern (>40° N) and southern (>40° N) part of EJS based on Sub Polar Front (SPF). Based on the SSN concentrations derived from satellite data, we found that the annual new production (Mean ± S.D = 85.6 ± 10.1 g C m−2 year−1) in the northern part of the EJS was significantly higher (t-test, p < 0.01) than that of the southern part of the EJS (Mean ± S.D = 65.6 ± 3.9 g C m−2 year−1). Given the relationships between the new productions and sea surface temperature (SST) in this study, the new production could be more susceptible in the northern part than the southern part of the EJS under consistent SST warming. Since the new production estimated in this study is only based on the nitrate inputs into the euphotic depths during the winter, new productions from additional nitrate sources (e.g., the nitrate upward flux through the MLD and atmospheric deposition) should be considered for estimating the annual new production.

Highlights

Various changes in physical, chemical and biological properties have been reported in the East/Japan Sea (EJS) during last several decades [1,2,3,4,5,6,7,8]
The annual new production had no specific trend in the EJS over the observation period from 2003 to 2015
The annual new productions in the northern and southern EJS were strongly negatively associated with the sea surface temperature (SST) in March (Figure 9)

Summary

Introduction

Chemical and biological properties have been reported in the East/Japan Sea (EJS) during last several decades [1,2,3,4,5,6,7,8]. A dramatic change in the vertical distribution of the chemical properties and sea surface temperature of the winter and spring was observed in the southern EJS during the last few decades [2,3,4]. The EJS has two main water-mass properties such as cold and warm waters. The different water mass leads to a gradient in environmental factors and phytoplankton dynamics in the EJS, which seems to be controlled by vertical variations in hydrographic features such as physical mixing and light-nutrient availability [20]. The vertical structure of the water column differs between the northern and southern parts of the EJS and is strongly associated with ecosystem dynamics [21]

Objectives

Results

Conclusion