Impact of the Strong Downwelling (Upwelling) on Small Pelagic Fish Production during the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java.

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The Strong Downwelling (Upwelling) Impact on Small Pelagic Fish Production During the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

10.20944/preprints202011.0071.v1 ◽

2020 ◽

Author(s):

Jonson Lumban-Gaol ◽

Eko Siswanto ◽

Nyoman Metah N. Natih ◽

I Wayan Nurjaya ◽

Mochammad Tri Hartanto ◽

...

Keyword(s):

Indian Ocean ◽

Phytoplankton Biomass ◽

Pelagic Fish ◽

Eastern Indian Ocean ◽

Fish Production ◽

Small Pelagic Fish ◽

Field Surveys ◽

Chl A ◽

Positive Indian Ocean Dipole ◽

The Impact

Although researchers have investigated widely the impact of IOD phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) of IOD on a chlorophyll a (Chl-a) concentration as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increasing) of small pelagic fish production in the EIO off Java.

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A biological Indian Ocean Dipole event in 2019

Scientific Reports ◽

10.1038/s41598-021-81410-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wei Shi ◽

Menghua Wang

Keyword(s):

Biological Activity ◽

Indian Ocean ◽

Indian Ocean Dipole ◽

Infrared Imaging ◽

Equatorial Indian Ocean ◽

The West ◽

Indian Ocean Dipole Event ◽

Chl A ◽

Positive Indian Ocean Dipole ◽

Dipole Response

AbstractThe 2019 positive Indian Ocean Dipole (IOD) event in the boreal autumn was the most serious IOD event of the century with reports of significant sea surface temperature (SST) changes in the east and west equatorial Indian Ocean. Observations of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) between 2012 and 2020 are used to study the significant biological dipole response that occurred in the equatorial Indian Ocean following the 2019 positive IOD event. For the first time, we propose, identify, characterize, and quantify the biological IOD. The 2019 positive IOD event led to anomalous biological activity in both the east IOD zone and west IOD zone. The average chlorophyll-a (Chl-a) concentration reached over ~ 0.5 mg m−3 in 2019 in comparison to the climatology Chl-a of ~ 0.3 mg m−3 in the east IOD zone. In the west IOD zone, the biological activity was significantly depressed. The depressed Chl-a lasted until May 2020. The anomalous ocean biological activity in the east IOD zone was attributed to the advection of the higher-nutrient surface water due to enhanced upwelling. On the other hand, the dampened ocean biological activity in the west IOD zone was attributed to the stronger convergence of the surface waters than that in a normal year.

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The impact of the positive Indian Ocean dipole on Zimbabwe droughts

International Journal of Climatology ◽

10.1002/joc.1695 ◽

2008 ◽

Vol 28 (15) ◽

pp. 2011-2029 ◽

Cited By ~ 26

Author(s):

D. Manatsa ◽

W. Chingombe ◽

C. H. Matarira

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

Positive Indian Ocean Dipole ◽

The Impact

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Assessing the Impact of Model Biases on the Projected Increase in Frequency of Extreme Positive Indian Ocean Dipole Events

Journal of Climate ◽

10.1175/jcli-d-16-0509.1 ◽

2017 ◽

Vol 30 (8) ◽

pp. 2757-2767 ◽

Cited By ~ 15

Author(s):

Guojian Wang ◽

Wenju Cai ◽

Agus Santoso

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

Equatorial Indian Ocean ◽

Climate Projections ◽

Systematic Bias ◽

Surface Cooling ◽

Frequency Increase ◽

Maximum Rainfall ◽

Positive Indian Ocean Dipole ◽

The Impact

For many generations, models simulate an Indian Ocean dipole (IOD) that is overly large in amplitude. The possible impact of this systematic bias on climate projections, including a projected frequency increase in extreme positive IOD (pIOD) using a rainfall-based definition, has attracted attention. In particular, a recent study suggests that the increased frequency is an artifact of the overly large IOD amplitude. In contrast, here the opposite is found. Through intermodel ensemble regressions, the present study shows that models producing a high frequency in the present-day climate generate a small future frequency increase. The frequency is associated with the mean equatorial west-minus-east sea surface temperature (SST) gradient: the greater the gradient, the greater the frequency because it is easier to shift convection to the west, which characterizes an extreme pIOD. A greater present-day gradient is associated with a present-day shallower thermocline, lower SSTs, and lower rainfall in the eastern equatorial Indian Ocean (EEIO). Because there is an inherent limit for a maximum rainfall reduction and for the impact on surface cooling by a shallowing of an already shallow mean EEIO thermocline, there is a smaller increase in frequency in models with a shallower present-day EEIO thermocline. Given that a bias of overly shallow EEIO thermocline and overly low EEIO SSTs and rainfall is common in models, the future frequency increase should be underestimated, opposite to an implied overestimation resulting from the overly large IOD amplitude bias. Therefore, correcting the projected frequency from a single bias, without considering other biases that are present, is not appropriate and should be avoided.

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Upwelling Impact on Sardinella lemuru during the Indian Ocean Dipole in the Bali Strait, Indonesia

Fishes ◽

10.3390/fishes6010008 ◽

2021 ◽

Vol 6 (1) ◽

pp. 8

Author(s):

Daduk Setyohadi ◽

Umi Zakiyah ◽

Abu Bakar Sambah ◽

Adi Wijaya

Keyword(s):

Indian Ocean ◽

Indian Ocean Dipole ◽

Phytoplankton Biomass ◽

Satellite Images ◽

Sea Surface ◽

Negative Phase ◽

Field Surveys ◽

The Indian Ocean ◽

The Government ◽

The Impact

Understanding the impact of Indian Ocean Dipole (IOD) on fishery around Indonesia is important as the fishery resources are small compared to the demand. In this study, we analyzed the effect of positive and negative phases of IOD on chlorophyll-a concentration and the catch of Sardinella lemuru in the Bali Strait. Data are based on field surveys in the Bali Strait during the positive and negative phase of IOD and Sea Surface Temperature (SST) and Sea Surface Chlorophyll (SSC) obtained from the analysis of satellite images. The results suggest that SSC concentration in the strait significantly correlates with the positive and negative phase of IOD, possibly through a change of upwelling and downwelling there. It is suggested that the change of phytoplankton biomass due to positive IOD would result in an increase of Sardinella lemuru in the Bali Strait. This research has direct implications as important information for the government in planning lemuru fisheries management in the Bali Strait based on oceanographic studies and climate phenomena.

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Tanzanian rainfall responses to El Niño and positive Indian Ocean Dipole events during 1951–2015

Atmospheric and Oceanic Science Letters ◽

10.1016/j.aosl.2021.100093 ◽

2021 ◽

pp. 100093

Author(s):

Dickson Mbigi ◽

Ziniu Xiao

Keyword(s):

Indian Ocean ◽

El Niño ◽

Indian Ocean Dipole ◽

El Nino ◽

Positive Indian Ocean Dipole

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Two-year consecutive concurrences of positive Indian Ocean Dipole and Central Pacific El Niño preconditioned the 2019/2020 Australian “black summer” bushfires

Geoscience Letters ◽

10.1186/s40562-020-00168-2 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Guojian Wang ◽

Wenju Cai

Keyword(s):

Indian Ocean ◽

El Niño ◽

Indian Ocean Dipole ◽

El Nino ◽

Greenhouse Warming ◽

Central Pacific ◽

Central Pacific El Niño ◽

Positive Indian Ocean Dipole ◽

The Future ◽

Rainfall Anomalies

Abstract The 2019/20 Australian black summer bushfires were particularly severe in many respects, including its early commencement, large spatial coverage, and large number of burning days, preceded by record dry and hot anomalies. Determining whether greenhouse warming has played a role is an important issue. Here, we examine known modes of tropical climate variability that contribute to droughts in Australia to provide a gauge. We find that a two-year consecutive concurrence of the 2018 and 2019 positive Indian Ocean Dipole and the 2018 and 2019 Central Pacific El Niño, with the former affecting Southeast Australia, and the latter influencing eastern and northeastern Australia, may explain many characteristics of the fires. Such consecutive events occurred only once in the observations since 1911. Using two generations of state-of-the-art climate models under historical and a business-as-usual emission scenario, we show that the frequency of such consecutive concurrences increases slightly, but rainfall anomalies during such events are stronger in the future climate, and there are drying trends across Australia. The impact of the stronger rainfall anomalies during such events under drying trends is likely to be exacerbated by greenhouse warming-induced rise in temperatures, making such events in the future even more extreme.

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DISTRIBUSI DAN POTENSI SUMBER DAYA IKAN PELAGIS DI WILAYAH PENGELOLAAN PERIKANAN NEGARA REPUBLIK INDONESIA 573 (WPP NRI 573) SAMUDERA HINDIA

Jurnal Penelitian Perikanan Indonesia ◽

10.15578/jppi.23.1.2017.47-56 ◽

2017 ◽

Vol 23 (1) ◽

pp. 47

Author(s):

Asep Ma'mun ◽

Asep Priatna ◽

Thomas Hidayat ◽

Nurulludin Nurulludin

Keyword(s):

Indian Ocean ◽

Distribution Pattern ◽

Sustainable Management ◽

Acoustic Method ◽

Pelagic Fish ◽

Small Pelagic Fish ◽

Fish Size ◽

Fish Resources ◽

Needed Information ◽

Pelagic Fisheries

Pengelolaan perikanan tangkap yang lestari membutuhkan informasi potensi dan pola penyebaran sumber daya ikan yang dimanfaatkan. Penelitian ini bertujuan untuk mengetahui distribusi dan potensi sumber daya ikan pelagis di WPP NRI 573 (perairan Samudera Hindia) dengan metode akustik. Hasil penelitian menunjukan, penyebaran densitas cukup tinggi untuk ikan pelagis ditemukan di perairan selatan Pangandaran hingga wilayah Jogjakarta. Sumber daya ikan pelagis kecil yang terdeteksi didominasi oleh ukuran ikan dengan kisaran panjang antara 25-28 cm dan ikan pelagis besar di dominasi oleh ukuran ikan 28-31 cm. Nilai rata-rata kepadatan stok untuk ikan pelagis kecil 0,041 ton/km2 dan ikan pelagis besar sebesar 0,14 ton/ km2. Potensi lestari ikan pelagis kecil sebesar 292.092 ton/tahun dan ikan pelagis besar sebesar 505.941 ton/tahun. Nilai tersebut dapat dijadikan dasar dalam upaya pengelolaan dan pemanfaatan perikanan pelagis.The sustainable management is needed information on the stock and distribution pattern of fish.This study aims to determine distribution and potential of fish resources especially for pelagic species in FMA 573 (Indian Ocean) by using acoustic method. Result of research indicated that, high density for pelagic fish found in south Pangandaran to Jogjakarta. The results obtained also that, the detected small pelagic fish were dominated by the fish size ranged between 25-28 cm and large pelagic fish was dominated by fish size of 28-31cm.The average of the stock density for small pelagic fish was 0,041 ton/km2 and large pelagic fish of 0.14 ton/km2.The sustainable potential of the small pelagic fish amounted to 292.092 ton/year and the large pelagic fish amounted to 505.941 ton/year. These values can be used as the basic management and utilization of pelagic fisheries in the waters region.

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Characteristics Fishing Areas of Bigeye Tuna (Thunnus Obesus) in Depth of 155 m Based on Remotely Sensed Data

Malaysian Journal of Applied Sciences ◽

10.37231/myjas.2020.5.1.235 ◽

2020 ◽

Vol 5 (1) ◽

pp. 62-70

Author(s):

Achmad Fachruddin-Syah ◽

Jonson Lumban Gaol ◽

Mukti Zainuddin ◽

Nadela Rista Apriliya ◽

Dessy Berlianty ◽

...

Keyword(s):

Indian Ocean ◽

Remotely Sensed ◽

Eastern Indian Ocean ◽

Bigeye Tuna ◽

Remotely Sensed Data ◽

Surface Salinity ◽

Chl A ◽

Fishing Vessels ◽

Thunnus Obesus ◽

Daily Data

Bigeye tuna (Thunnus obesus) is one of the commercially important pelagic species that caught mostly in the eastern Indian Ocean. This species prefers to stay close, and is usually below the thermocline layer. Remotely sensed data was used to determine the characteristics of Bigeye tuna fishing areas at a depth of 155 meter. Fishing vessels for Bigeye tuna were obtained from vessel monitoring systems (VMS) from January through December, 2015-2016. Daily data on sub-surface temperature (SST), sub-surface chlorophyll-a concentration (SSC), and sub-surface salinity (SSS) were obtained from the INDESO Project website. All oceanographic parameter data were selected at a depth of 155 m. The position of Bigeye tuna and oceanographic data were then grouped into 2 group monsoon, southeast monsoon (April – September) and northwest monsoon (October – March). The results showed that, during the southeast and northwest monsoon, Bigeye tuna mostly found in SSC of 0.03 – 0.05 mg/m3, SST of 16° - 18°C and salinity of 34 psu. These results showed that at depth of 155 m, Bigeye Tuna prefers to stay in small chl-a (0.03 – 0.04 mg/m3), low SST (16° - 18°C) and salinity of 34 psu. These information were essential and could be used to support fisheries management decisions especially for Bigeye Tuna in the eastern Indian Ocean.

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