Variability of Ocean Primary Productivity and Zooplankton Biomass Based on Ecosystem Model Over Natuna Sea and its Correlation with Climate Factors
Muhammad Firman Nuruddin, Nafissa Adyan Fekranie, Tahnia Hafizha Tresnoadi, Parikesit Nurul Azmi, Sunarto

Intitut Teknologi Bandung

Abstract

Natuna sea, one of the productive fisheries area, produce at least 1.2 million tons of fish per year, is threatened by the dynamics of climate. The ocean productivity in this area is affected by annual climate variabilities which are monsoon and inter-annual phenomena (El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD)). Marine phytoplankton and zooplankton respond quickly to climate related disturbances with complex spectra, seeking to identify the main causes of confused and observed changes. This study aimed to determine the impact of climate variability on the ocean productivity- net primary productivity and zooplankton biomass, in Natuna Sea. This study used daily Ocean Productivity Data during 1998 to 2018 from NEMO PISCESv2 model with spatial resolution 0.0083 x 0.0083, provided by Copernicus Marine Service Information. Cross correlation and wavelet transform coherence methods were used to analyze the change of ocean productivity and determine which climate factors that more dominant in Natuna Sea. As result, the number of NPP monthly average for 20 years in Natuna Sea was in range 267.73 to 563.24 mgC.m^-2.day^-1, while the zooplankton biomass was in range 131.29 to 315.72 mgC.m^-2. Besides, the peak value of NPP and Zooplankton biomass happened during the east monsoon with the average 504.88 mgC.m^-2.day^-1 and 282.26 mgC.m^-2, while the lowest was during the transitional 1 monsoon with the average 307.17 mgC.m^-2.day^-1 and 138.71 mgC.m^-2 respectively. The cross-correlation analysis between inter-annual phenomena and the ocean productivity shown that the variability of ocean productivity in Natuna Sea during 1998-2018 was more influenced by the ENSO rather than IOD with the lag time 0 and 1 months for ONI-NPP and ONI-Zooplankton. Meanwhile, the lag time between IOD phenomena with the variability of NPP and zooplankton biomass was 2 and 1 months, respectively.

Keywords: IOD, ENSO, Monsoon, NPP, zooplankton

Topic: Oceanography (International)