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Upwelling) on Small Pelagic Fish Production During the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean Off Java

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Upwelling) on Small Pelagic Fish Production During the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean Off Java climate Article 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 Jonson Lumban-Gaol 1,*, Eko Siswanto 2 , Kedarnath Mahapatra 3 , Nyoman Metta Nyanakumara Natih 1, I Wayan Nurjaya 1, Mochamad Tri Hartanto 1, Erwin Maulana 1, Luky Adrianto 4, Herlambang Aulia Rachman 5, Takahiro Osawa 6, Berri Miraz Kholipah Rahman 7 and Arik Permana 8 1 Department of Marine Science and Technology, Faculty of Fisheries and Marine Science, IPB University, Bogor 16680, Indonesia; [email protected] (N.M.N.N.); [email protected] (I.W.N.); [email protected] (M.T.H.); [email protected] (E.M.) 2 Earth Surface System Research Center, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25, Showa-machi, Kanazawa-ku, Yokohama, Kanagawa 236-0001, Japan; [email protected] 3 School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu 424-8610, Japan; [email protected] 4 Department of Aquatic Resources Management, Faculty of Fisheries and Marine Science, IPB University, Bogor 16680, Indonesia; [email protected] 5 Marine Technology, Faculty of Fisheries and Marine Science, IPB University, Bogor 16680, Indonesia; [email protected] Citation: Lumban-Gaol, J.; Siswanto, 6 Center for Remote Sensing and Ocean Science (CReSOS), Udayana University, Post Graduate Building, E.; Mahapatra, K.; Natih, N.M.N.; Denpasar 80232, Indonesia; [email protected] Nurjaya, IW.; Hartanto, M.T.; 7 Marine Fisheries Technology, Faculty of Fisheries and Marine Science, IPB University, Bogor 16680, Indonesia; Maulana, E.; Adrianto, L.; Rachman, [email protected] 8 H.A.; Osawa, T.; et al. Impact of the Faculty of Fisheries and Marine Science, IPB University, Bogor 16680, Indonesia; [email protected] Strong Downwelling (Upwelling) on * Correspondence: [email protected] Small Pelagic Fish Production during the 2016 (2019) Negative (Positive) Abstract: Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases Indian Ocean Dipole Events in the on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the Eastern Indian Ocean off Java. Climate influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator 2021, 9, 29. https://doi.org/10.3390/ of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off cli9020029 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 Received: 13 December 2020 a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative Accepted: 11 January 2021 (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) Published: 02 February 2021 IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in Keywords: chlorophyll-a; climate change; IOD; Palabuhanratu Bay; pelagic fishery; sea surface temperature published maps and institutional affil- iations. 1. Introduction Copyright: © 2021 by the authors. The Indian Ocean Dipole (IOD) is well-known as a dominant mode of interannual Licensee MDPI, Basel, Switzerland. climate variability that develops from air–sea interactions in the Indian Ocean. With This article is an open access article anomalously low sea surface temperatures (SST) associated with strong upwelling in the distributed under the terms and eastern Indian Ocean (EIO) off Java–Sumatra and high SST in the western Indian Ocean, it conditions of the Creative Commons is known as the IOD positive phases (pIOD). Featuring opposite anomalies over a similar Attribution (CC BY) license (https:// region are the IOD negative phases (nIOD) [1–3]. The pIOD events have become stronger creativecommons.org/licenses/by/ and more frequent, particularly since the 1960s [4,5]. The publications by Abram et al. [4] 4.0/). Climate 2021, 9, 29. https://doi.org/10.3390/cli9020029 https://www.mdpi.com/journal/climate Climate 2021, 9, x FOR PEER REVIEW 2 of 12 western Indian Ocean, it is known as the IOD positive phases (pIOD). Featuring op‐ posite anomalies over a similar region are the IOD negative phases (nIOD) [1–3]. The Climate 2021, 9, 29 pIOD events have become stronger and more frequent, particularly since the 1960s 2 of 11 [4,5]. The publications by Abram et al. [4] and Cai et al. [5] indicate that the change in IOD occurrences can be attributed to climate change and to greenhouse warming [6]. Researchers have widely investigated the impact of IOD phases on human lives. They and Cai et al. [5] indicate that the change in IOD occurrences can be attributed to climate have found it to be considerably large, particularly with respect to socioeconomics. For change and to greenhouse warming [6]. example, the IOD plays an important role in monsoon rainfall. The rainfall over East Af‐ Researchers have widely investigated the impact of IOD phases on human lives. They rica (Indonesia) increases (decreases) during a pIOD phase [7]. High rainfall during the have found it to be considerably large, particularly with respect to socioeconomics. For pIOD serves as a driving force in the resurgence of malaria in the East African highlands example, the IOD plays an important role in monsoon rainfall. The rainfall over East Africa [8,9]. Furthermore,(Indonesia) there have increases been reports (decreases) on the during impact a pIOD of IOD phase on southeast [7]. High Australian rainfall during the pIOD bushfires [10] andserves Zimbabwean as a driving droughts force in [11]. the resurgence of malaria in the East African highlands [8,9]. The impactFurthermore, of the IOD on there the havephysical been structure reports of on the the Indian impact Ocean of IOD is well on known. southeast Australian The stronger‐thanbushfires‐normal [10 ]seasonal and Zimbabwean southeasterly droughts winds [11 along]. the Java–Sumatra coasts during the pIOD phaseThe impact have intensified of the IOD coastal on the physical upwelling structure [12]. During of the Indian the pIOD Ocean phase, is well known. The the intense upwellingstronger-than-normal event occurs seasonalconcurrently southeasterly with a chlorophyll winds along a (Chl the Java–Sumatra‐a) bloom off coasts during the South Javathe and pIOD Sumatra phase coasts have [13–15]. intensified Meanwhile, coastal upwelling during the [12 ].2016 During nIOD, the the pIOD down phase,‐ the intense welling event upwellingoccurred concurrently event occurs with concurrently a Chl‐a withdecrease a chlorophyll along the a coasts (Chl-a) of bloom Sumatra off the South Java and Java [16]. and Sumatra coasts [13–15]. Meanwhile, during the 2016 nIOD, the downwelling event Althoughoccurred many researchers concurrently have with tried a Chl-ato understand decrease IOD along impacts, the coasts only of Sumatraa few have and Java [16]. examined such impactsAlthough on small many pelagic researchers fisheries. have Generally, tried to understand during the IODpIOD, impacts, fish pro only‐ a few have duction increasedexamined sharply such in impactsthe EIO on owing small to pelagic increased fisheries. upwelling Generally, [17–19], during but the nIOD pIOD, fish produc- phase impacts tionon fish increased production sharply are innot the well EIO known owing in to the increased EIO off upwellingJava. [17–19], but nIOD phase Accordingimpacts to mass on media fish production information, are small not well pelagic known fish inlanding the EIO in offthe Java. fishing ports tended to decrease Accordingduring negative to mass IOD media phases information, from 2016 small to 2017. pelagic Conversely, fish landing it tended in the fishing ports to increase duringtended the to2019 decrease pIOD. during The high negative fluctuation IOD phases in the fish from landing 2016 to during 2017. Conversely, the IOD it tended to phases has influencedincrease socio during‐economic the 2019 activities. pIOD. The Usually, high fluctuation if the quantum in the of fish fish landing landing during the IOD decreases, the phasesprice of has fish influenced increases, socio-economicand as a result, the activities. raw materials Usually, for if the quantumfishing in‐ of fish landing dustry reduce.decreases, However, the quantity price of fishof these increases, raw materials and as aincreases result, the during raw an materials increase for the fishing in fish landing.industry reduce. However, the quantity of these raw materials increases during an increase The Dipolein Mode fish landing. Index (DMI) shows that 2016 and 2019 could be two of the most extreme nIOD and ThepIOD Dipole years Modeever, respectively Index (DMI) [20,21], shows as that shown 2016 in and Figure 2019 1. could The nega be two‐ of the most tive and positiveextreme impacts nIOD of this and phenomenon pIOD years ever, need respectively to be investigated [20,21], as to shown enhance in Figure under1‐. The negative standing with andrespect positive to small impacts pelagic of this fishery phenomenon production need and to to be predict investigated of future to enhance produc‐ understanding tions. with respect to small pelagic fishery production and to predict of future productions. Figure 1. DipoleFigure Mode 1. Dipole Index Mode showing Index the showing occurrence the occurrence of the negative of the phases negative (blue) phases and (blue) positive and phases positive (red) of Indian Ocean Dipolesphases during (red) 1980–2019. of Indian Ocean The negative Dipoles andduring positive 1980–2019. extreme The Indian negative Ocean and Dipolespositive occurred extreme Indian in 2016 and 2019, respectively,Ocean marked Dipoles with theoccurred years ofin pronounced2016 and 2019, negative respectively, and positive marked anomalies.
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